From: Viktor Szakats <commit@vsz.me>
Date: Tue, 5 Aug 2025 14:07:21 +0000 (+0200)
Subject: autotools: tidy-up `if` expressions
X-Git-Tag: rc-8_18_0-2~46
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8db0e286b363ad788d6dc0779d605b83c7ed4caf;p=thirdparty%2Fcurl.git

autotools: tidy-up `if` expressions

- drop x-hacks for curl internal variables and certain autotools ones
  that do not hold custom values.
- make x-hacks consistently use `"x$var" = "xval"` style.
- add a few x-hacks for input/external variables that may hold custom
  values.
- prefer `-z` and `-n` to test empty/non-empty.
  This also makes some x-hacks unnecessary.
- optimized negated test `-z` and `-n` options.
- prefer `&&` and `||` over `-a` and `-o`.
  For better POSIX compatibility:
  https://pubs.opengroup.org/onlinepubs/9699919799/utilities/test.html
- quote variables passed to `test`, where missing.
- quote string literals in comparisons.
- fix some indentation, whitespace.

Note that a few `case` statements also use the x-hack, which looks
unnecessary. This patch does not change them.

Verified by comparing feature detection results with a reference CI run
from before this patch (PR #19922).

Refs:
https://www.shellcheck.net/wiki/SC2268
https://pubs.opengroup.org/onlinepubs/9699919799/utilities/test.html
https://www.vidarholen.net/contents/blog/?p=1035
https://mywiki.wooledge.org/BashPitfalls#A.5B_.24foo_.3D_.22bar.22_.5D

Closes #18189
---

diff --git a/acinclude.m4 b/acinclude.m4
index 0627ed1fd7..d95cbd3f5b 100644
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -190,7 +190,7 @@ AC_DEFUN([CURL_CHECK_NATIVE_WINDOWS], [
       curl_cv_native_windows="no"
     ])
   ])
-  AM_CONDITIONAL(DOING_NATIVE_WINDOWS, test "x$curl_cv_native_windows" = xyes)
+  AM_CONDITIONAL(DOING_NATIVE_WINDOWS, test "$curl_cv_native_windows" = "yes")
 ])
 
 
@@ -910,7 +910,7 @@ AC_DEFUN([CURL_CHECK_LIBS_CLOCK_GETTIME_MONOTONIC], [
         curl_func_clock_gettime="yes"
         ;;
       *)
-        if test "x$dontwant_rt" = "xyes" ; then
+        if test "$dontwant_rt" = "yes"; then
           AC_MSG_WARN([needs -lrt but asked not to use it, HAVE_CLOCK_GETTIME_MONOTONIC will not be defined])
           curl_func_clock_gettime="no"
         else
@@ -926,7 +926,7 @@ AC_DEFUN([CURL_CHECK_LIBS_CLOCK_GETTIME_MONOTONIC], [
     esac
     #
     dnl only do runtime verification when not cross-compiling
-    if test "x$cross_compiling" != "xyes" &&
+    if test "$cross_compiling" != "yes" &&
       test "$curl_func_clock_gettime" = "yes"; then
       AC_MSG_CHECKING([if monotonic clock_gettime works])
       CURL_RUN_IFELSE([
@@ -1082,7 +1082,7 @@ dnl macro. It must also run AFTER all lib-checking macros are complete.
 AC_DEFUN([CURL_VERIFY_RUNTIMELIBS], [
 
   dnl this test is of course not sensible if we are cross-compiling!
-  if test "x$cross_compiling" != xyes; then
+  if test "$cross_compiling" != "yes"; then
 
     dnl just run a program to verify that the libs checked for previous to this
     dnl point also is available runtime!
@@ -1149,22 +1149,22 @@ AS_HELP_STRING([--without-ca-path], [Do not use a default CA path]),
   capath_warning="   (warning: certs not found)"
   check_capath=""
 
-  if test "x$APPLE_SECTRUST_ENABLED" = "x1"; then
+  if test "$APPLE_SECTRUST_ENABLED" = "1"; then
     ca_native="Apple SecTrust"
   else
     ca_native="no"
   fi
 
-  if test "x$want_ca" != "xno" -a "x$want_ca" != "xunset" -a \
-          "x$want_capath" != "xno" -a "x$want_capath" != "xunset"; then
+  if test "x$want_ca" != "xno" && test "x$want_ca" != "xunset" &&
+     test "x$want_capath" != "xno" && test "x$want_capath" != "xunset"; then
     dnl both given
     ca="$want_ca"
     capath="$want_capath"
-  elif test "x$want_ca" != "xno" -a "x$want_ca" != "xunset"; then
+  elif test "x$want_ca" != "xno" && test "x$want_ca" != "xunset"; then
     dnl --with-ca-bundle given
     ca="$want_ca"
     capath="no"
-  elif test "x$want_capath" != "xno" -a "x$want_capath" != "xunset"; then
+  elif test "x$want_capath" != "xno" && test "x$want_capath" != "xunset"; then
     dnl --with-ca-path given
     capath="$want_capath"
     ca="no"
@@ -1177,15 +1177,15 @@ AS_HELP_STRING([--without-ca-path], [Do not use a default CA path]),
     dnl Both auto-detections can be skipped by --without-ca-*
     ca="no"
     capath="no"
-    if test "x$cross_compiling" != "xyes" -a \
-            "x$curl_cv_native_windows" != "xyes"; then
+    if test "$cross_compiling" != "yes" &&
+       test "$curl_cv_native_windows" != "yes"; then
       dnl NOT cross-compiling and...
       dnl neither of the --with-ca-* options are provided
       if test "x$want_ca" = "xunset"; then
         dnl the path we previously would have installed the curl CA bundle
         dnl to, and thus we now check for an already existing cert in that
         dnl place in case we find no other
-        if test "x$prefix" != xNONE; then
+        if test "x$prefix" != "xNONE"; then
           cac="${prefix}/share/curl/curl-ca-bundle.crt"
         else
           cac="$ac_default_prefix/share/curl/curl-ca-bundle.crt"
@@ -1221,7 +1221,7 @@ AS_HELP_STRING([--without-ca-path], [Do not use a default CA path]),
     check_capath="$capath"
   fi
 
-  if test ! -z "$check_capath"; then
+  if test -n "$check_capath"; then
     for a in "$check_capath"; do
       if test -d "$a" && ls "$a"/[[0-9a-f][0-9a-f][0-9a-f][0-9a-f][0-9a-f][0-9a-f][0-9a-f][0-9a-f]].0 >/dev/null 2>/dev/null; then
         if test "x$capath" = "xno"; then
@@ -1257,14 +1257,14 @@ AS_HELP_STRING([--without-ca-path], [Do not use a default CA path]),
 AS_HELP_STRING([--with-ca-fallback], [Use OpenSSL's built-in CA store])
 AS_HELP_STRING([--without-ca-fallback], [Do not use OpenSSL's built-in CA store]),
   [
-    if test "x$with_ca_fallback" != "xyes" -a "x$with_ca_fallback" != "xno"; then
+    if test "x$with_ca_fallback" != "xyes" && test "x$with_ca_fallback" != "xno"; then
       AC_MSG_ERROR([--with-ca-fallback only allows yes or no as parameter])
     fi
   ],
   [ with_ca_fallback="no"])
   AC_MSG_RESULT([$with_ca_fallback])
   if test "x$with_ca_fallback" = "xyes"; then
-    if test "x$OPENSSL_ENABLED" != "x1"; then
+    if test "$OPENSSL_ENABLED" != "1"; then
       AC_MSG_ERROR([--with-ca-fallback only works with OpenSSL])
     fi
     AC_DEFINE_UNQUOTED(CURL_CA_FALLBACK, 1, [define "1" to use OpenSSL's built-in CA store])
@@ -1293,7 +1293,7 @@ AS_HELP_STRING([--without-ca-embed], [Do not embed a default CA bundle in the cu
   [ want_ca_embed="unset" ])
 
   CURL_CA_EMBED=''
-  if test "x$want_ca_embed" != "xno" -a "x$want_ca_embed" != "xunset" -a -f "$want_ca_embed"; then
+  if test "x$want_ca_embed" != "xno" && test "x$want_ca_embed" != "xunset" && test -f "$want_ca_embed"; then
     if test -n "$PERL"; then
       CURL_CA_EMBED="$want_ca_embed"
       AC_SUBST(CURL_CA_EMBED)
@@ -1315,7 +1315,7 @@ AC_DEFUN([CURL_CHECK_WIN32_CRYPTO], [
   AC_REQUIRE([CURL_CHECK_NATIVE_WINDOWS])dnl
   AC_MSG_CHECKING([whether build target supports Win32 crypto API])
   curl_win32_crypto_api="no"
-  if test "$curl_cv_native_windows" = "yes" -a "$curl_cv_winuwp" != "yes"; then
+  if test "$curl_cv_native_windows" = "yes" && test "$curl_cv_winuwp" != "yes"; then
     AC_COMPILE_IFELSE([
       AC_LANG_PROGRAM([[
         #undef inline
@@ -1382,7 +1382,7 @@ AC_DEFUN([CURL_CHECK_PKGCONFIG], [
       [$PATH:/usr/bin:/usr/local/bin])
   fi
 
-  if test "x$PKGCONFIG" != "xno"; then
+  if test "$PKGCONFIG" != "no"; then
     AC_MSG_CHECKING([for $1 options with pkg-config])
     dnl ask pkg-config about $1
     itexists=`CURL_EXPORT_PCDIR([$2]) dnl
@@ -1423,7 +1423,7 @@ dnl Save build info for test runner to pick up and log
 
 AC_DEFUN([CURL_PREPARE_BUILDINFO], [
   curl_pflags=""
-  if test "$curl_cv_apple" = 'yes'; then
+  if test "$curl_cv_apple" = "yes"; then
     curl_pflags="${curl_pflags} APPLE"
   fi
   case $host in
@@ -1443,20 +1443,20 @@ AC_DEFUN([CURL_PREPARE_BUILDINFO], [
       fi
       ;;
   esac
-  if test "$curl_cv_native_windows" = 'yes'; then
+  if test "$curl_cv_native_windows" = "yes"; then
     curl_pflags="${curl_pflags} WIN32"
   fi
-  if test "$curl_cv_winuwp" = 'yes'; then
+  if test "$curl_cv_winuwp" = "yes"; then
     curl_pflags="${curl_pflags} UWP"
   fi
-  if test "$curl_cv_cygwin" = 'yes'; then
+  if test "$curl_cv_cygwin" = "yes"; then
     curl_pflags="${curl_pflags} CYGWIN"
   fi
   case $host_os in
     msdos*) curl_pflags="${curl_pflags} DOS";;
     amiga*) curl_pflags="${curl_pflags} AMIGA";;
   esac
-  if test "x$compiler_id" = 'xGNU_C'; then
+  if test "$compiler_id" = "GNU_C"; then
     curl_pflags="${curl_pflags} GCC"
   fi
   if test "$compiler_id" = "APPLECLANG"; then
@@ -1467,7 +1467,7 @@ AC_DEFUN([CURL_PREPARE_BUILDINFO], [
   case $host_os in
     mingw*) curl_pflags="${curl_pflags} MINGW";;
   esac
-  if test "x$cross_compiling" = 'xyes'; then
+  if test "$cross_compiling" = "yes"; then
     curl_pflags="${curl_pflags} CROSS"
   fi
   squeeze curl_pflags
@@ -1509,7 +1509,7 @@ TEST EINVAL TEST
   AC_MSG_RESULT([$cpp])
 
   dnl we need cpp -P so check if it works then
-  if test "x$cpp" = "xyes"; then
+  if test "$cpp" = "yes"; then
     AC_MSG_CHECKING([if cpp -P works])
     OLDCPPFLAGS=$CPPFLAGS
     CPPFLAGS="$CPPFLAGS -P"
@@ -1519,7 +1519,7 @@ TEST EINVAL TEST
     ], [cpp_p=yes], [cpp_p=no])
     AC_MSG_RESULT([$cpp_p])
 
-    if test "x$cpp_p" = "xno"; then
+    if test "$cpp_p" = "no"; then
       AC_MSG_WARN([failed to figure out cpp -P alternative])
       # without -P
       CPPPFLAG=""
diff --git a/configure.ac b/configure.ac
index 40d4fc29fe..3c0bfaa353 100644
--- a/configure.ac
+++ b/configure.ac
@@ -44,12 +44,12 @@ AM_MAINTAINER_MODE
 m4_ifdef([AM_SILENT_RULES], [AM_SILENT_RULES([yes])])
 
 CURL_CHECK_OPTION_DEBUG
-AM_CONDITIONAL(DEBUGBUILD, test x$want_debug = xyes)
+AM_CONDITIONAL(DEBUGBUILD, test "$want_debug" = "yes")
 CURL_CHECK_OPTION_OPTIMIZE
 CURL_CHECK_OPTION_WARNINGS
 CURL_CHECK_OPTION_WERROR
 CURL_CHECK_OPTION_CURLDEBUG
-AM_CONDITIONAL(CURLDEBUG, test x$want_curldebug = xyes)
+AM_CONDITIONAL(CURLDEBUG, test "$want_curldebug" = "yes")
 CURL_CHECK_OPTION_SYMBOL_HIDING
 CURL_CHECK_OPTION_ARES
 CURL_CHECK_OPTION_RT
@@ -225,7 +225,7 @@ AS_HELP_STRING([--with-ssl=PATH],[old version of --with-openssl])
 AS_HELP_STRING([--without-ssl], [build without any TLS library]),[
   OPT_SSL=$withval
   OPT_OPENSSL=$withval
-  if test X"$withval" != Xno; then
+  if test "x$withval" != "xno"; then
     TLSCHOICE="${TLSCHOICE:+$TLSCHOICE, }OpenSSL"
   else
     SSL_DISABLED="D"
@@ -235,7 +235,7 @@ AS_HELP_STRING([--without-ssl], [build without any TLS library]),[
 AC_ARG_WITH(openssl,dnl
 AS_HELP_STRING([--with-openssl=PATH],[Where to look for OpenSSL, PATH points to the SSL installation (default: /usr/local/ssl); when possible, set the PKG_CONFIG_PATH environment variable instead of using this option]),[
   OPT_OPENSSL=$withval
-  if test X"$withval" != Xno; then
+  if test "x$withval" != "xno"; then
     TLSCHOICE="${TLSCHOICE:+$TLSCHOICE, }OpenSSL"
   fi
 ])
@@ -244,7 +244,7 @@ OPT_GNUTLS=no
 AC_ARG_WITH(gnutls,dnl
 AS_HELP_STRING([--with-gnutls=PATH],[where to look for GnuTLS, PATH points to the installation root]),[
   OPT_GNUTLS=$withval
-  if test X"$withval" != Xno; then
+  if test "x$withval" != "xno"; then
     TLSCHOICE="${TLSCHOICE:+$TLSCHOICE, }GnuTLS"
   fi
 ])
@@ -253,7 +253,7 @@ OPT_MBEDTLS=no
 AC_ARG_WITH(mbedtls,dnl
 AS_HELP_STRING([--with-mbedtls=PATH],[where to look for mbedTLS, PATH points to the installation root]),[
   OPT_MBEDTLS=$withval
-  if test X"$withval" != Xno; then
+  if test "x$withval" != "xno"; then
     TLSCHOICE="${TLSCHOICE:+$TLSCHOICE, }mbedTLS"
   fi
 ])
@@ -262,7 +262,7 @@ OPT_WOLFSSL=no
 AC_ARG_WITH(wolfssl,dnl
 AS_HELP_STRING([--with-wolfssl=PATH],[where to look for wolfSSL, PATH points to the installation root (default: system lib default)]),[
   OPT_WOLFSSL=$withval
-  if test X"$withval" != Xno; then
+  if test "x$withval" != "xno"; then
     TLSCHOICE="${TLSCHOICE:+$TLSCHOICE, }wolfSSL"
   fi
 ])
@@ -271,7 +271,7 @@ OPT_RUSTLS=no
 AC_ARG_WITH(rustls,dnl
 AS_HELP_STRING([--with-rustls=PATH],[where to look for Rustls, PATH points to the installation root]),[
   OPT_RUSTLS=$withval
-  if test X"$withval" != Xno; then
+  if test "x$withval" != "xno"; then
     TLSCHOICE="${TLSCHOICE:+$TLSCHOICE, }Rustls"
     experimental="$experimental Rustls"
   fi
@@ -291,7 +291,7 @@ TEST_NGHTTPX=nghttpx
 AC_ARG_WITH(test-nghttpx,dnl
 AS_HELP_STRING([--with-test-nghttpx=PATH],[where to find nghttpx for testing]),
   TEST_NGHTTPX=$withval
-  if test X"$TEST_NGHTTPX" = "Xno"; then
+  if test "x$TEST_NGHTTPX" = "xno"; then
     TEST_NGHTTPX=""
   fi
 )
@@ -307,7 +307,7 @@ fi
 AC_ARG_WITH(test-caddy,dnl
 AS_HELP_STRING([--with-test-caddy=PATH],[where to find caddy for testing]),
   CADDY=$withval
-  if test X"$CADDY" = "Xno"; then
+  if test "x$CADDY" = "xno"; then
     CADDY=""
   fi
 )
@@ -323,7 +323,7 @@ fi
 AC_ARG_WITH(test-vsftpd,dnl
 AS_HELP_STRING([--with-test-vsftpd=PATH],[where to find vsftpd for testing]),
   VSFTPD=$withval
-  if test X"$VSFTPD" = "Xno"; then
+  if test "x$VSFTPD" = "xno"; then
     VSFTPD=""
   fi
 )
@@ -335,31 +335,31 @@ HTTPD_ENABLED="maybe"
 AC_ARG_WITH(test-httpd, [AS_HELP_STRING([--with-test-httpd=PATH],
                          [where to find httpd/apache2 for testing])],
   [request_httpd=$withval], [request_httpd=check])
-if test x"$request_httpd" = "xcheck" -o x"$request_httpd" = "xyes"; then
+if test "x$request_httpd" = "xcheck" || test "x$request_httpd" = "xyes"; then
   if test -x "/usr/sbin/apache2"; then
     # common location on distros (debian/ubuntu)
     HTTPD="/usr/sbin/apache2"
     AC_PATH_PROG([APXS], [apxs])
-    if test "x$APXS" = "x"; then
+    if test -z "$APXS"; then
       AC_MSG_NOTICE([apache2-dev not installed, httpd tests disabled])
       HTTPD_ENABLED="no"
     fi
   else
     AC_PATH_PROG([HTTPD], [httpd])
-    if test "x$HTTPD" = "x"; then
+    if test -z "$HTTPD"; then
       AC_PATH_PROG([HTTPD], [apache2])
     fi
     AC_PATH_PROG([APXS], [apxs])
-    if test "x$HTTPD" = "x"; then
+    if test -z "$HTTPD"; then
       AC_MSG_NOTICE([httpd/apache2 not in PATH, http tests disabled])
       HTTPD_ENABLED="no"
     fi
-    if test "x$APXS" = "x"; then
+    if test -z "$APXS"; then
       AC_MSG_NOTICE([apxs not in PATH, http tests disabled])
       HTTPD_ENABLED="no"
     fi
   fi
-elif test x"$request_httpd" != "xno"; then
+elif test "x$request_httpd" != "xno"; then
   HTTPD="${request_httpd}/bin/httpd"
   APXS="${request_httpd}/bin/apxs"
   if test ! -x "${HTTPD}"; then
@@ -372,7 +372,7 @@ elif test x"$request_httpd" != "xno"; then
     AC_MSG_NOTICE([using HTTPD=$HTTPD for tests])
   fi
 fi
-if test x"$HTTPD_ENABLED" = "xno"; then
+if test "$HTTPD_ENABLED" = "no"; then
   HTTPD=""
   APXS=""
 fi
@@ -385,17 +385,17 @@ DANTED_ENABLED="maybe"
 AC_ARG_WITH(test-danted, [AS_HELP_STRING([--with-test-danted=PATH],
                          [where to find danted socks daemon for testing])],
   [request_danted=$withval], [request_danted=check])
-if test x"$request_danted" = "xcheck" -o x"$request_danted" = "xyes"; then
+if test "x$request_danted" = "xcheck" || test "x$request_danted" = "xyes"; then
   if test -x "/usr/sbin/danted"; then
     # common location on distros (debian/ubuntu)
     DANTED="/usr/sbin/danted"
   else
     AC_PATH_PROG([DANTED], [danted])
-    if test "x$DANTED" = "x"; then
+    if test -z "$DANTED"; then
       AC_PATH_PROG([DANTED], [danted])
     fi
   fi
-elif test x"$request_danted" != "xno"; then
+elif test "x$request_danted" != "xno"; then
   DANTED="${request_danted}"
   if test ! -x "${DANTED}"; then
     AC_MSG_NOTICE([danted not found as ${DANTED}, danted tests disabled])
@@ -404,13 +404,13 @@ elif test x"$request_danted" != "xno"; then
     AC_MSG_NOTICE([using DANTED=$DANTED for tests])
   fi
 fi
-if test x"$DANTED_ENABLED" = "xno"; then
+if test "$DANTED_ENABLED" = "no"; then
   DANTED=""
 fi
 AC_SUBST(DANTED)
 
 dnl the nghttpx we might use in httpd testing
-if test "x$TEST_NGHTTPX" != "x" -a "x$TEST_NGHTTPX" != "xnghttpx"; then
+if test -n "$TEST_NGHTTPX" && test "x$TEST_NGHTTPX" != "xnghttpx"; then
   HTTPD_NGHTTPX="$TEST_NGHTTPX"
 else
   AC_PATH_PROG([HTTPD_NGHTTPX], [nghttpx], [],
@@ -419,7 +419,7 @@ fi
 AC_SUBST(HTTPD_NGHTTPX)
 
 dnl the Caddy server we might use in testing
-if test "x$TEST_CADDY" != "x"; then
+if test -n "$TEST_CADDY"; then
   CADDY="$TEST_CADDY"
 else
   AC_PATH_PROG([CADDY], [caddy])
@@ -480,11 +480,11 @@ AM_CONDITIONAL(NOT_CURL_CI, test -z "$CURL_CI")
 #
 
 AM_CONDITIONAL([CURL_LT_SHLIB_USE_VERSION_INFO],
-  [test "x$xc_lt_shlib_use_version_info" = 'xyes'])
+  [test "$xc_lt_shlib_use_version_info" = "yes"])
 AM_CONDITIONAL([CURL_LT_SHLIB_USE_NO_UNDEFINED],
-  [test "x$xc_lt_shlib_use_no_undefined" = 'xyes'])
+  [test "$xc_lt_shlib_use_no_undefined" = "yes"])
 AM_CONDITIONAL([CURL_LT_SHLIB_USE_MIMPURE_TEXT],
-  [test "x$xc_lt_shlib_use_mimpure_text" = 'xyes'])
+  [test "$xc_lt_shlib_use_mimpure_text" = "yes"])
 
 #
 # Due to libtool and automake machinery limitations of not allowing
@@ -503,7 +503,7 @@ AM_CONDITIONAL([CURL_LT_SHLIB_USE_MIMPURE_TEXT],
 #
 
 AM_CONDITIONAL([USE_CPPFLAG_CURL_STATICLIB],
-  [test "x$xc_lt_build_static_only" = 'xyes'])
+  [test "$xc_lt_build_static_only" = "yes"])
 
 #
 # Make staticlib CPPFLAG variable and its definition visible in output
@@ -515,7 +515,7 @@ LIBCURL_PC_CFLAGS_PRIVATE='-DCURL_STATICLIB'
 AC_SUBST(LIBCURL_PC_CFLAGS_PRIVATE)
 
 LIBCURL_PC_CFLAGS=
-if test "x$xc_lt_build_static_only" = 'xyes'; then
+if test "$xc_lt_build_static_only" = "yes"; then
   LIBCURL_PC_CFLAGS="${LIBCURL_PC_CFLAGS_PRIVATE}"
 fi
 AC_SUBST([LIBCURL_PC_CFLAGS])
@@ -555,7 +555,7 @@ if test "$compiler_id" = "INTEL_UNIX_C"; then
 fi
 
 CURL_CFLAG_EXTRAS=""
-if test X"$want_werror" = Xyes; then
+if test "$want_werror" = "yes"; then
   CURL_CFLAG_EXTRAS="-Werror"
   if test "$compiler_id" = "GNU_C"; then
     dnl enable -pedantic-errors for GCC 5 and later,
@@ -563,12 +563,12 @@ if test X"$want_werror" = Xyes; then
     if test "$compiler_num" -ge "500"; then
       CURL_CFLAG_EXTRAS="$CURL_CFLAG_EXTRAS -pedantic-errors"
     fi
-  elif test "$compiler_id" = "CLANG" -o "$compiler_id" = "APPLECLANG"; then
+  elif test "$compiler_id" = "CLANG" || test "$compiler_id" = "APPLECLANG"; then
     CURL_CFLAG_EXTRAS="$CURL_CFLAG_EXTRAS -pedantic-errors"
   fi
 fi
 AC_SUBST(CURL_CFLAG_EXTRAS)
-AM_CONDITIONAL(CURL_WERROR, test X"$want_werror" = Xyes)
+AM_CONDITIONAL(CURL_WERROR, test "$want_werror" = "yes")
 
 CURL_CHECK_COMPILER_HALT_ON_ERROR
 CURL_CHECK_COMPILER_ARRAY_SIZE_NEGATIVE
@@ -579,8 +579,8 @@ supports_unittests=yes
 # cross-compilation of unit tests static library/programs fails when
 # libcurl shared library is built. This might be due to a libtool or
 # automake issue. In this case we disable unit tests.
-if test "x$cross_compiling" != "xno" &&
-   test "x$enable_shared" != "xno"; then
+if test "$cross_compiling" != "no" &&
+   test "$enable_shared" != "no"; then
   supports_unittests=no
 fi
 
@@ -604,7 +604,7 @@ case $host_os in
     ;;
 esac
 
-AM_CONDITIONAL(BUILD_UNITTESTS, test x$supports_unittests = xyes)
+AM_CONDITIONAL(BUILD_UNITTESTS, test "$supports_unittests" = "yes")
 
 # In order to detect support of sendmmsg() and accept4(), we need to escape the POSIX
 # jail by defining _GNU_SOURCE or <sys/socket.h> will not expose it.
@@ -625,7 +625,7 @@ case $host in
   *-apple-*) curl_cv_apple='yes';;
 esac
 
-if test "$curl_cv_apple" = 'yes'; then
+if test "$curl_cv_apple" = "yes"; then
   CURL_DARWIN_CFLAGS
   CURL_SUPPORTS_BUILTIN_AVAILABLE
 fi
@@ -663,11 +663,11 @@ AS_HELP_STRING([--disable-unity],[Disable unity (default)]),
   esac ],
     AC_MSG_RESULT([no])
 )
-if test -z "$PERL" -a "$want_unity" = 'yes'; then
+if test -z "$PERL" && test "$want_unity" = "yes"; then
   AC_MSG_WARN([perl was not found. Will not enable unity.])
   want_unity='no'
 fi
-AM_CONDITIONAL([USE_UNITY], [test "$want_unity" = 'yes'])
+AM_CONDITIONAL([USE_UNITY], [test "$want_unity" = "yes"])
 
 dnl ************************************************************
 dnl switch off particular protocols
@@ -745,7 +745,7 @@ AS_HELP_STRING([--disable-ipfs],[Disable IPFS support]),
     CURL_DISABLE_IPFS=1
     ;;
   *)
-    if test x$CURL_DISABLE_HTTP = x1; then
+    if test "$CURL_DISABLE_HTTP" = "1"; then
       AC_MSG_ERROR(HTTP support needs to be enabled in order to enable IPFS support!)
     else
       AC_MSG_RESULT(yes)
@@ -753,7 +753,7 @@ AS_HELP_STRING([--disable-ipfs],[Disable IPFS support]),
     fi
     ;;
   esac ],
-    if test "x$CURL_DISABLE_HTTP" != "x1"; then
+    if test "$CURL_DISABLE_HTTP" != "1"; then
       AC_MSG_RESULT(yes)
       curl_ipfs_msg="enabled"
     else
@@ -791,7 +791,7 @@ AS_HELP_STRING([--disable-ldaps],[Disable LDAPS support]),
     CURL_DISABLE_LDAPS=1
     ;;
   *)
-    if test "x$CURL_DISABLE_LDAP" = "x1"; then
+    if test "$CURL_DISABLE_LDAP" = "1"; then
       AC_MSG_RESULT(LDAP needs to be enabled to support LDAPS)
       AC_DEFINE(CURL_DISABLE_LDAPS, 1, [to disable LDAPS])
       CURL_DISABLE_LDAPS=1
@@ -802,7 +802,7 @@ AS_HELP_STRING([--disable-ldaps],[Disable LDAPS support]),
     fi
     ;;
   esac ],[
-    if test "x$CURL_DISABLE_LDAP" = "x1"; then
+    if test "$CURL_DISABLE_LDAP" = "1"; then
       AC_MSG_RESULT(no)
       AC_DEFINE(CURL_DISABLE_LDAPS, 1, [to disable LDAPS])
       CURL_DISABLE_LDAPS=1
@@ -817,27 +817,27 @@ AC_MSG_CHECKING([whether to support rtsp])
 AC_ARG_ENABLE(rtsp,
 AS_HELP_STRING([--enable-rtsp],[Enable RTSP support])
 AS_HELP_STRING([--disable-rtsp],[Disable RTSP support]),
-  [ case "$enableval" in
-      no)
+[ case "$enableval" in
+    no)
+    AC_MSG_RESULT(no)
+    AC_DEFINE(CURL_DISABLE_RTSP, 1, [to disable RTSP])
+    CURL_DISABLE_RTSP=1
+    ;;
+  *)
+    if test "$CURL_DISABLE_HTTP" = "1"; then
+      AC_MSG_ERROR(HTTP support needs to be enabled in order to enable RTSP support!)
+    else
+      AC_MSG_RESULT(yes)
+      curl_rtsp_msg="enabled"
+    fi
+    ;;
+  esac ],
+    if test "$CURL_DISABLE_HTTP" != "1"; then
+      AC_MSG_RESULT(yes)
+      curl_rtsp_msg="enabled"
+    else
       AC_MSG_RESULT(no)
-      AC_DEFINE(CURL_DISABLE_RTSP, 1, [to disable RTSP])
-      CURL_DISABLE_RTSP=1
-      ;;
-    *)
-      if test x$CURL_DISABLE_HTTP = x1; then
-        AC_MSG_ERROR(HTTP support needs to be enabled in order to enable RTSP support!)
-      else
-        AC_MSG_RESULT(yes)
-        curl_rtsp_msg="enabled"
-      fi
-      ;;
-    esac ],
-      if test "x$CURL_DISABLE_HTTP" != "x1"; then
-        AC_MSG_RESULT(yes)
-        curl_rtsp_msg="enabled"
-      else
-        AC_MSG_RESULT(no)
-      fi
+    fi
 )
 
 AC_MSG_CHECKING([whether to support proxies])
@@ -892,7 +892,7 @@ AS_HELP_STRING([--disable-telnet],[Disable TELNET support]),
     AC_MSG_RESULT(yes)
 )
 
-if test "$curl_cv_winuwp" = 'yes'; then
+if test "$curl_cv_winuwp" = "yes"; then
   AC_DEFINE(CURL_DISABLE_TELNET, 1, [to disable TELNET])
   CURL_DISABLE_TELNET=1
 fi
@@ -1063,7 +1063,7 @@ AS_HELP_STRING([--disable-docs],[Disable documentation]),
     AC_MSG_RESULT(yes)
     BUILD_DOCS=1
 )
-if test -z "$PERL" -a "x$BUILD_DOCS" != "x0"; then
+if test -z "$PERL" && test "$BUILD_DOCS" != "0"; then
   AC_MSG_WARN([perl was not found. Will not build documentation.])
   BUILD_DOCS=0
 fi
@@ -1191,14 +1191,14 @@ fi
 
 # In UWP mode gethostbyname gets detected via the core libs, but some
 # code (in6addr_any) still need ws2_32, so let us detect and add it.
-if test "$HAVE_GETHOSTBYNAME" != "1" -o "$curl_cv_winuwp" = "yes"; then
+if test "$HAVE_GETHOSTBYNAME" != "1" || test "$curl_cv_winuwp" = "yes"; then
   if test "$curl_cv_native_windows" = "yes"; then
     dnl This is for Winsock systems
     winsock_LIB="-lws2_32"
     if test "$curl_cv_winuwp" != "yes"; then
       winsock_LIB="$winsock_LIB -liphlpapi"
     fi
-    if test ! -z "$winsock_LIB"; then
+    if test -n "$winsock_LIB"; then
       my_ac_save_LIBS=$LIBS
       LIBS="$winsock_LIB $LIBS"
       AC_MSG_CHECKING([for gethostbyname in $winsock_LIB])
@@ -1261,7 +1261,7 @@ if test "$HAVE_GETHOSTBYNAME" != "1"; then
   ])
 fi
 
-if test "$HAVE_GETHOSTBYNAME" != "1" -o "${with_amissl+set}" = set; then
+if test "$HAVE_GETHOSTBYNAME" != "1" || test "${with_amissl+set}" = "set"; then
   dnl This is for AmigaOS with bsdsocket.library - needs testing before -lnet
   AC_MSG_CHECKING([for gethostbyname for AmigaOS bsdsocket.library])
   AC_LINK_IFELSE([
@@ -1331,10 +1331,10 @@ AS_HELP_STRING([--with-zlib=PATH],[search for zlib in PATH])
 AS_HELP_STRING([--without-zlib],[disable use of zlib]),
   [OPT_ZLIB="$withval"])
 
-if test "$OPT_ZLIB" = "no"; then
+if test "x$OPT_ZLIB" = "xno"; then
   AC_MSG_WARN([zlib disabled])
 else
-  if test "$OPT_ZLIB" = "yes"; then
+  if test "x$OPT_ZLIB" = "xyes"; then
     OPT_ZLIB=""
   fi
 
@@ -1434,7 +1434,7 @@ else
 fi
 
 dnl set variable for use in automakefile(s)
-AM_CONDITIONAL(HAVE_LIBZ, test x"$AMFIXLIB" = x1)
+AM_CONDITIONAL(HAVE_LIBZ, test "$AMFIXLIB" = "1")
 AC_SUBST(ZLIB_LIBS)
 
 dnl **********************************************************************
@@ -1450,7 +1450,7 @@ AS_HELP_STRING([--with-brotli=PATH],[Where to look for brotli, PATH points to th
 AS_HELP_STRING([--without-brotli], [disable BROTLI]),
   OPT_BROTLI=$withval)
 
-if test X"$OPT_BROTLI" != Xno; then
+if test "x$OPT_BROTLI" != "xno"; then
   dnl backup the pre-brotli variables
   CLEANLDFLAGS="$LDFLAGS"
   CLEANLDFLAGSPC="$LDFLAGSPC"
@@ -1509,7 +1509,7 @@ if test X"$OPT_BROTLI" != Xno; then
     AC_DEFINE(HAVE_BROTLI, 1, [if BROTLI is in use])
   )
 
-  if test X"$OPT_BROTLI" != Xoff &&
+  if test "x$OPT_BROTLI" != "xoff" &&
      test "$HAVE_BROTLI" != "1"; then
     AC_MSG_ERROR([BROTLI libs and/or directories were not found where specified!])
   fi
@@ -1520,7 +1520,7 @@ if test X"$OPT_BROTLI" != Xno; then
       dnl linker does not search through, we need to add it to CURL_LIBRARY_PATH
       dnl to prevent further configure tests to fail due to this
 
-      if test "x$cross_compiling" != "xyes"; then
+      if test "$cross_compiling" != "yes"; then
         CURL_LIBRARY_PATH="$CURL_LIBRARY_PATH:$DIR_BROTLI"
         export CURL_LIBRARY_PATH
         AC_MSG_NOTICE([Added $DIR_BROTLI to CURL_LIBRARY_PATH])
@@ -1547,7 +1547,7 @@ AS_HELP_STRING([--with-zstd=PATH],[Where to look for libzstd, PATH points to the
 AS_HELP_STRING([--without-zstd], [disable libzstd]),
   OPT_ZSTD=$withval)
 
-if test X"$OPT_ZSTD" != Xno; then
+if test "x$OPT_ZSTD" != "xno"; then
   dnl backup the pre-zstd variables
   CLEANLDFLAGS="$LDFLAGS"
   CLEANLDFLAGSPC="$LDFLAGSPC"
@@ -1598,7 +1598,7 @@ if test X"$OPT_ZSTD" != Xno; then
     AC_DEFINE(HAVE_ZSTD, 1, [if libzstd is in use])
   )
 
-  if test X"$OPT_ZSTD" != Xoff &&
+  if test "x$OPT_ZSTD" != "xoff" &&
      test "$HAVE_ZSTD" != "1"; then
     AC_MSG_ERROR([libzstd was not found where specified!])
   fi
@@ -1610,7 +1610,7 @@ if test X"$OPT_ZSTD" != Xno; then
       dnl CURL_LIBRARY_PATH to prevent further configure tests to fail due to
       dnl this
 
-      if test "x$cross_compiling" != "xyes"; then
+      if test "$cross_compiling" != "yes"; then
         CURL_LIBRARY_PATH="$CURL_LIBRARY_PATH:$DIR_ZSTD"
         export CURL_LIBRARY_PATH
         AC_MSG_NOTICE([Added $DIR_ZSTD to CURL_LIBRARY_PATH])
@@ -1674,7 +1674,7 @@ AS_HELP_STRING([--disable-ipv6],[Disable IPv6 support]),
   )
 )
 
-if test "$ipv6" = yes; then
+if test "$ipv6" = "yes"; then
   curl_ipv6_msg="enabled"
   AC_DEFINE(USE_IPV6, 1, [Define if you want to enable IPv6 support])
   IPV6_ENABLED=1
@@ -1732,7 +1732,7 @@ int main(int argc, char **argv)
 ],[
   curl_cv_writable_argv=cross
 ])
-if test "$curl_cv_writable_argv" = 'cross' -a "$curl_cv_apple" = 'yes'; then
+if test "$curl_cv_writable_argv" = "cross" && test "$curl_cv_apple" = "yes"; then
   curl_cv_writable_argv=yes
 fi
 case $curl_cv_writable_argv in
@@ -1773,9 +1773,9 @@ AC_ARG_WITH(gssapi-libs,
 AC_ARG_WITH(gssapi,
   AS_HELP_STRING([--with-gssapi=DIR], [Where to look for GSS-API]), [
     GSSAPI_ROOT="$withval"
-    if test x"$GSSAPI_ROOT" != xno; then
+    if test "$GSSAPI_ROOT" != "no"; then
       want_gss="yes"
-      if test x"$GSSAPI_ROOT" = xyes; then
+      if test "$GSSAPI_ROOT" = "yes"; then
         dnl if yes, then use default root
         GSSAPI_ROOT="/usr"
       fi
@@ -1787,16 +1787,16 @@ AC_ARG_WITH(gssapi,
 
 save_CPPFLAGS="$CPPFLAGS"
 AC_MSG_CHECKING([if GSS-API support is requested])
-if test x"$want_gss" = xyes; then
+if test "$want_gss" = "yes"; then
   AC_MSG_RESULT(yes)
 
-  if test $GSSAPI_ROOT != "/usr"; then
+  if test "$GSSAPI_ROOT" != "/usr"; then
     CURL_CHECK_PKGCONFIG(mit-krb5-gssapi, $GSSAPI_ROOT/lib/pkgconfig)
   else
     CURL_CHECK_PKGCONFIG(mit-krb5-gssapi)
   fi
   if test -z "$GSSAPI_INCS"; then
-    if test -n "$host_alias" -a -f "$GSSAPI_ROOT/bin/$host_alias-krb5-config"; then
+    if test -n "$host_alias" && test -f "$GSSAPI_ROOT/bin/$host_alias-krb5-config"; then
       GSSAPI_INCS=`$GSSAPI_ROOT/bin/$host_alias-krb5-config --cflags gssapi`
     elif test "$PKGCONFIG" != "no"; then
       GSSAPI_INCS=`$PKGCONFIG --cflags mit-krb5-gssapi`
@@ -1821,7 +1821,7 @@ if test x"$want_gss" = xyes; then
         [gssapi/gssapi.h gssapi/gssapi_generic.h gssapi/gssapi_krb5.h],
         [],
         [not_mit=1])
-      if test "x$not_mit" = "x1"; then
+      if test "$not_mit" = "1"; then
         dnl MIT not found
         AC_MSG_ERROR([MIT or GNU GSS library required, but not found])
       fi
@@ -1830,7 +1830,7 @@ if test x"$want_gss" = xyes; then
 else
   AC_MSG_RESULT(no)
 fi
-if test x"$want_gss" = xyes; then
+if test "$want_gss" = "yes"; then
   AC_DEFINE(HAVE_GSSAPI, 1, [if you have GSS-API libraries])
   HAVE_GSSAPI=1
   curl_gss_msg="enabled (MIT Kerberos)"
@@ -1843,15 +1843,15 @@ if test x"$want_gss" = xyes; then
     LIBS="-lgss $LIBS"
     link_pkgconfig=1
   elif test -z "$GSSAPI_LIB_DIR"; then
-    if test "$curl_cv_apple" = 'yes'; then
+    if test "$curl_cv_apple" = "yes"; then
       LIBS="-lgssapi_krb5 -lresolv $LIBS"
     else
-      if test $GSSAPI_ROOT != "/usr"; then
+      if test "$GSSAPI_ROOT" != "/usr"; then
         CURL_CHECK_PKGCONFIG(mit-krb5-gssapi, $GSSAPI_ROOT/lib/pkgconfig)
       else
         CURL_CHECK_PKGCONFIG(mit-krb5-gssapi)
       fi
-      if test -n "$host_alias" -a -f "$GSSAPI_ROOT/bin/$host_alias-krb5-config"; then
+      if test -n "$host_alias" && test -f "$GSSAPI_ROOT/bin/$host_alias-krb5-config"; then
         dnl krb5-config does not have --libs-only-L or similar, put everything
         dnl into LIBS
         gss_libs=`$GSSAPI_ROOT/bin/$host_alias-krb5-config --libs gssapi`
@@ -1886,7 +1886,7 @@ if test x"$want_gss" = xyes; then
       fi
     fi
     gss_version=""
-    if test -n "$host_alias" -a -f "$GSSAPI_ROOT/bin/$host_alias-krb5-config"; then
+    if test -n "$host_alias" && test -f "$GSSAPI_ROOT/bin/$host_alias-krb5-config"; then
       gss_version=`$GSSAPI_ROOT/bin/$host_alias-krb5-config --version | $SED 's/Kerberos 5 release //'`
     elif test "$PKGCONFIG" != "no"; then
       gss_version=`$PKGCONFIG --modversion mit-krb5-gssapi`
@@ -1920,7 +1920,7 @@ else
   CPPFLAGS="$save_CPPFLAGS"
 fi
 
-if test x"$want_gss" = xyes; then
+if test "$want_gss" = "yes"; then
   AC_MSG_CHECKING([if we can link against GSS-API library])
   AC_LINK_IFELSE([
     AC_LANG_FUNC_LINK_TRY([gss_init_sec_context])
@@ -1933,11 +1933,11 @@ if test x"$want_gss" = xyes; then
 fi
 
 build_libstubgss=no
-if test x"$want_gss" = "xyes"; then
+if test "$want_gss" = "yes"; then
   build_libstubgss=yes
 fi
 
-AM_CONDITIONAL(BUILD_STUB_GSS, test "x$build_libstubgss" = "xyes")
+AM_CONDITIONAL(BUILD_STUB_GSS, test "$build_libstubgss" = "yes")
 
 dnl -------------------------------------------------------------
 dnl parse --with-default-ssl-backend so it can be validated below
@@ -1974,12 +1974,12 @@ CURL_WITH_RUSTLS
 CURL_WITH_APPLE_SECTRUST
 
 dnl link required libraries for USE_WIN32_CRYPTO or SCHANNEL_ENABLED
-if test "x$USE_WIN32_CRYPTO" = "x1" -o "x$SCHANNEL_ENABLED" = "x1"; then
+if test "$USE_WIN32_CRYPTO" = "1" || test "$SCHANNEL_ENABLED" = "1"; then
   LIBS="-ladvapi32 -lcrypt32 $LIBS"
 fi
 
 dnl link bcrypt for BCryptGenRandom() (used when building for Vista or newer)
-if test "x$curl_cv_native_windows" = "xyes"; then
+if test "$curl_cv_native_windows" = "yes"; then
   LIBS="-lbcrypt $LIBS"
 fi
 
@@ -2014,13 +2014,13 @@ if test -n "$ssl_backends"; then
   curl_ssl_msg="enabled ($ssl_backends)"
 fi
 
-if test no = "$VALID_DEFAULT_SSL_BACKEND"; then
+if test "$VALID_DEFAULT_SSL_BACKEND" = "no"; then
   if test -n "$SSL_ENABLED"; then
     AC_MSG_ERROR([Default SSL backend $DEFAULT_SSL_BACKEND not enabled!])
   else
     AC_MSG_ERROR([Default SSL backend requires SSL!])
   fi
-elif test yes = "$VALID_DEFAULT_SSL_BACKEND"; then
+elif test "$VALID_DEFAULT_SSL_BACKEND" = "yes"; then
   AC_DEFINE_UNQUOTED([CURL_DEFAULT_SSL_BACKEND], ["$DEFAULT_SSL_BACKEND"], [Default SSL backend])
 fi
 
@@ -2033,7 +2033,7 @@ if test -n "$check_for_ca_bundle"; then
   CURL_CHECK_CA_EMBED
 fi
 
-AM_CONDITIONAL(CURL_CA_EMBED_SET, test "x$CURL_CA_EMBED" != "x")
+AM_CONDITIONAL(CURL_CA_EMBED_SET, test -n "$CURL_CA_EMBED")
 
 dnl ----------------------
 dnl check unsafe CA search
@@ -2090,7 +2090,7 @@ AS_HELP_STRING([--with-libpsl=PATH],[Where to look for libpsl, PATH points to th
 AS_HELP_STRING([--without-libpsl], [disable LIBPSL]),
   OPT_LIBPSL=$withval)
 
-if test X"$OPT_LIBPSL" != Xno; then
+if test "x$OPT_LIBPSL" != "xno"; then
   dnl backup the pre-libpsl variables
   CLEANLDFLAGS="$LDFLAGS"
   CLEANLDFLAGSPC="$LDFLAGSPC"
@@ -2163,7 +2163,7 @@ AS_HELP_STRING([--with-libgsasl=PATH],[Where to look for libgsasl, PATH points t
 AS_HELP_STRING([--without-libgsasl], [disable libgsasl support for SCRAM]),
   OPT_LIBGSASL=$withval)
 
-if test "$OPT_LIBGSASL" != no; then
+if test "x$OPT_LIBGSASL" != "xno"; then
   dnl backup the pre-libgsasl variables
   CLEANLDFLAGS="$LDFLAGS"
   CLEANLDFLAGSPC="$LDFLAGSPC"
@@ -2243,7 +2243,7 @@ AS_HELP_STRING([--with-libssh=PATH],[Where to look for libssh, PATH points to th
 AS_HELP_STRING([--with-libssh], [enable libssh]),
   OPT_LIBSSH=$withval, OPT_LIBSSH=no)
 
-if test X"$OPT_LIBSSH2" != Xno; then
+if test "x$OPT_LIBSSH2" != "xno"; then
   dnl backup the pre-libssh2 variables
   CLEANLDFLAGS="$LDFLAGS"
   CLEANLDFLAGSPC="$LDFLAGSPC"
@@ -2295,7 +2295,7 @@ if test X"$OPT_LIBSSH2" != Xno; then
     USE_LIBSSH2=1
   )
 
-  if test X"$OPT_LIBSSH2" != Xoff &&
+  if test "x$OPT_LIBSSH2" != "xoff" &&
      test "$USE_LIBSSH2" != "1"; then
     AC_MSG_ERROR([libssh2 libs and/or directories were not found where specified!])
   fi
@@ -2306,7 +2306,7 @@ if test X"$OPT_LIBSSH2" != Xno; then
       dnl linker does not search through, we need to add it to CURL_LIBRARY_PATH
       dnl to prevent further configure tests to fail due to this
 
-      if test "x$cross_compiling" != "xyes"; then
+      if test "$cross_compiling" != "yes"; then
         CURL_LIBRARY_PATH="$CURL_LIBRARY_PATH:$DIR_SSH2"
         export CURL_LIBRARY_PATH
         AC_MSG_NOTICE([Added $DIR_SSH2 to CURL_LIBRARY_PATH])
@@ -2320,7 +2320,7 @@ if test X"$OPT_LIBSSH2" != Xno; then
     CPPFLAGS=$CLEANCPPFLAGS
     LIBS=$CLEANLIBS
   fi
-elif test X"$OPT_LIBSSH" != Xno; then
+elif test "x$OPT_LIBSSH" != "xno"; then
   dnl backup the pre-libssh variables
   CLEANLDFLAGS="$LDFLAGS"
   CLEANLDFLAGSPC="$LDFLAGSPC"
@@ -2371,7 +2371,7 @@ elif test X"$OPT_LIBSSH" != Xno; then
     USE_LIBSSH=1
   )
 
-  if test X"$OPT_LIBSSH" != Xoff &&
+  if test "x$OPT_LIBSSH" != "xoff" &&
      test "$USE_LIBSSH" != "1"; then
     AC_MSG_ERROR([libssh libs and/or directories were not found where specified!])
   fi
@@ -2386,7 +2386,7 @@ elif test X"$OPT_LIBSSH" != Xno; then
       dnl linker does not search through, we need to add it to CURL_LIBRARY_PATH
       dnl to prevent further configure tests to fail due to this
 
-      if test "x$cross_compiling" != "xyes"; then
+      if test "$cross_compiling" != "yes"; then
         CURL_LIBRARY_PATH="$CURL_LIBRARY_PATH:$DIR_SSH"
         export CURL_LIBRARY_PATH
         AC_MSG_NOTICE([Added $DIR_SSH to CURL_LIBRARY_PATH])
@@ -2456,14 +2456,14 @@ case "$OPT_LDAP" in
     ;;
 esac
 
-if test x$CURL_DISABLE_LDAP != x1 && test "$want_ldap" != "no"; then
+if test "$CURL_DISABLE_LDAP" != "1" && test "$want_ldap" != "no"; then
 
   CURL_CHECK_HEADER_LBER
   CURL_CHECK_HEADER_LDAP
   CURL_CHECK_HEADER_LDAP_SSL
 
   if test -z "$LDAPLIBNAME"; then
-    if test "$curl_cv_native_windows" = "yes" -a "$curl_cv_winuwp" != "yes"; then
+    if test "$curl_cv_native_windows" = "yes" && test "$curl_cv_winuwp" != "yes"; then
       dnl Windows uses a single and unique LDAP library name
       LDAPLIBNAME="wldap32"
       LBERLIBNAME="no"
@@ -2472,7 +2472,7 @@ if test x$CURL_DISABLE_LDAP != x1 && test "$want_ldap" != "no"; then
 
   if test "$LDAPLIBNAME"; then
     dnl If we have both LDAP and LBER library names, check if we need both
-    if test "$LBERLIBNAME" -a "$LBERLIBNAME" != "no"; then
+    if test "$LBERLIBNAME" && test "$LBERLIBNAME" != "no"; then
       dnl Try LDAP first, then with LBER if needed
       AC_CHECK_LIB("$LDAPLIBNAME", ldap_init, [ldap_lib_ok=yes], [ldap_lib_ok=no])
       if test "$ldap_lib_ok" = "no"; then
@@ -2527,7 +2527,7 @@ if test x$CURL_DISABLE_LDAP != x1 && test "$want_ldap" != "no"; then
   fi
 fi
 
-if test x$CURL_DISABLE_LDAP != x1; then
+if test "$CURL_DISABLE_LDAP" != "1"; then
   dnl Add to library path if needed
   if test -n "$DIR_LDAP"; then
     dnl when the ldap shared lib were found in a path that the runtime
@@ -2535,7 +2535,7 @@ if test x$CURL_DISABLE_LDAP != x1; then
     dnl CURL_LIBRARY_PATH to prevent further configure tests to fail due to
     dnl this
 
-    if test "x$cross_compiling" != "xyes"; then
+    if test "$cross_compiling" != "yes"; then
       CURL_LIBRARY_PATH="$CURL_LIBRARY_PATH:$DIR_LDAP"
       export CURL_LIBRARY_PATH
       AC_MSG_NOTICE([Added $DIR_LDAP to CURL_LIBRARY_PATH])
@@ -2546,7 +2546,7 @@ if test x$CURL_DISABLE_LDAP != x1; then
     dnl If name is "no" then do not define this library at all
     dnl (it is only needed if libldap.so's dependencies are broken).
     dnl Skip this check if we already determined we need both libraries above
-    if test "$LBERLIBNAME" != "no" -a "$ldap_lib_ok" != "yes"; then
+    if test "$LBERLIBNAME" != "no" && test "$ldap_lib_ok" != "yes"; then
       AC_CHECK_LIB("$LBERLIBNAME", ber_free,, [
         AC_MSG_WARN(["$LBERLIBNAME" is not an LBER library: LDAP disabled])
         AC_DEFINE(CURL_DISABLE_LDAP, 1, [to disable LDAP])
@@ -2563,7 +2563,7 @@ if test x$CURL_DISABLE_LDAP != x1; then
   fi
 fi
 
-if test x$CURL_DISABLE_LDAP != x1; then
+if test "$CURL_DISABLE_LDAP" != "1"; then
   AC_CHECK_FUNCS([ldap_url_parse \
                   ldap_init_fd])
 
@@ -2571,7 +2571,7 @@ if test x$CURL_DISABLE_LDAP != x1; then
     curl_ldap_msg="enabled (winldap)"
     AC_DEFINE(USE_WIN32_LDAP, 1, [Use Windows LDAP implementation])
   else
-    if test "x$ac_cv_func_ldap_init_fd" = "xyes"; then
+    if test "$ac_cv_func_ldap_init_fd" = "yes"; then
       curl_ldap_msg="enabled (OpenLDAP)"
       AC_DEFINE(USE_OPENLDAP, 1, [Use OpenLDAP-specific code])
       USE_OPENLDAP=1
@@ -2581,7 +2581,7 @@ if test x$CURL_DISABLE_LDAP != x1; then
   fi
 fi
 
-if test x$CURL_DISABLE_LDAPS != x1; then
+if test "$CURL_DISABLE_LDAPS" != "1"; then
   curl_ldaps_msg="enabled"
 fi
 
@@ -2596,7 +2596,7 @@ AS_HELP_STRING([--with-librtmp=PATH],[Where to look for librtmp, PATH points to
 AS_HELP_STRING([--without-librtmp], [disable LIBRTMP]),
   OPT_LIBRTMP=$withval)
 
-if test X"$OPT_LIBRTMP" != Xno; then
+if test "x$OPT_LIBRTMP" != "xno"; then
   dnl backup the pre-librtmp variables
   CLEANLDFLAGS="$LDFLAGS"
   CLEANLDFLAGSPC="$LDFLAGSPC"
@@ -2660,7 +2660,7 @@ if test X"$OPT_LIBRTMP" != Xno; then
       LIBS=$CLEANLIBS
   )
 
-  if test X"$OPT_LIBRTMP" != Xoff &&
+  if test "x$OPT_LIBRTMP" != "xoff" &&
      test "$USE_LIBRTMP" != "1"; then
     AC_MSG_ERROR([librtmp libs and/or directories were not found where specified!])
   fi
@@ -2690,17 +2690,17 @@ AS_HELP_STRING([--disable-versioned-symbols], [Disable versioned symbols in shar
       AC_MSG_RESULT(yes)
       if test "x$enableval" != "xyes"; then
         versioned_symbols_flavour="$enableval"
-      elif test "x$CURL_WITH_MULTI_SSL" = "x1"; then
+      elif test "$CURL_WITH_MULTI_SSL" = "1"; then
         versioned_symbols_flavour="MULTISSL_"
-      elif test "x$OPENSSL_ENABLED" = "x1"; then
+      elif test "$OPENSSL_ENABLED" = "1"; then
         versioned_symbols_flavour="OPENSSL_"
-      elif test "x$MBEDTLS_ENABLED" = "x1"; then
+      elif test "$MBEDTLS_ENABLED" = "1"; then
         versioned_symbols_flavour="MBEDTLS_"
-      elif test "x$WOLFSSL_ENABLED" = "x1"; then
+      elif test "$WOLFSSL_ENABLED" = "1"; then
         versioned_symbols_flavour="WOLFSSL_"
-      elif test "x$GNUTLS_ENABLED" = "x1"; then
+      elif test "$GNUTLS_ENABLED" = "1"; then
         versioned_symbols_flavour="GNUTLS_"
-      elif test "x$RUSTLS_ENABLED" = "x1"; then
+      elif test "$RUSTLS_ENABLED" = "1"; then
         versioned_symbols_flavour="RUSTLS_"
       else
         versioned_symbols_flavour=""
@@ -2718,7 +2718,7 @@ AS_HELP_STRING([--disable-versioned-symbols], [Disable versioned symbols in shar
 AC_SUBST([CURL_LIBCURL_VERSIONED_SYMBOLS_PREFIX], ["$versioned_symbols_flavour"])
 AC_SUBST([CURL_LIBCURL_VERSIONED_SYMBOLS_SONAME], ["4"])  dnl Keep in sync with VERSIONCHANGE - VERSIONDEL in lib/Makefile.soname
 AM_CONDITIONAL([CURL_LT_SHLIB_USE_VERSIONED_SYMBOLS],
-  [test "x$versioned_symbols" = 'xyes'])
+  [test "$versioned_symbols" = "yes"])
 
 dnl ----------------------------
 dnl check Windows Unicode option
@@ -2726,7 +2726,7 @@ dnl ----------------------------
 
 want_winuni="no"
 if test "$curl_cv_native_windows" = "yes"; then
-  if test "$curl_cv_winuwp" = 'yes'; then
+  if test "$curl_cv_winuwp" = "yes"; then
     want_winuni="yes"
   else
     AC_MSG_CHECKING([whether to enable Windows Unicode (Windows native builds only)])
@@ -2758,7 +2758,7 @@ dnl check WinIDN option before other IDN libraries
 dnl -------------------------------------------------
 
 tst_links_winidn='no'
-if test "$curl_cv_native_windows" = 'yes'; then
+if test "$curl_cv_native_windows" = "yes"; then
   AC_MSG_CHECKING([whether to enable Windows native IDN (Windows native builds only)])
   OPT_WINIDN="default"
   AC_ARG_WITH(winidn,
@@ -2848,7 +2848,7 @@ dnl Check for the presence of AppleIDN
 dnl **********************************************************************
 
 tst_links_appleidn='no'
-if test "$curl_cv_apple" = 'yes'; then
+if test "$curl_cv_apple" = "yes"; then
   AC_MSG_CHECKING([whether to build with Apple IDN])
   OPT_IDN="default"
   AC_ARG_WITH(apple-idn,
@@ -2887,10 +2887,10 @@ AC_ARG_WITH(libidn2,
 AS_HELP_STRING([--with-libidn2=PATH],[Enable libidn2 usage])
 AS_HELP_STRING([--without-libidn2],[Disable libidn2 usage]),
   [OPT_IDN=$withval])
-if test "x$tst_links_winidn" = "xyes"; then
+if test "$tst_links_winidn" = "yes"; then
   want_idn="no"
   AC_MSG_RESULT([no (using WinIDN instead)])
-elif test "x$tst_links_appleidn" = "xyes"; then
+elif test "$tst_links_appleidn" = "yes"; then
   want_idn="no"
   AC_MSG_RESULT([no (using AppleIDN instead)])
 else
@@ -2998,7 +2998,7 @@ if test "$want_idn" = "yes"; then
 
     IDN_ENABLED=1
     curl_idn_msg="enabled (libidn2)"
-    if test -n "$IDN_DIR" -a "x$cross_compiling" != "xyes"; then
+    if test -n "$IDN_DIR" && test "$cross_compiling" != "yes"; then
       CURL_LIBRARY_PATH="$CURL_LIBRARY_PATH:$IDN_DIR"
       export CURL_LIBRARY_PATH
       AC_MSG_NOTICE([Added $IDN_DIR to CURL_LIBRARY_PATH])
@@ -3020,7 +3020,7 @@ dnl **********************************************************************
 
 OPT_H2="yes"
 
-if test "x$disable_http" = "xyes"; then
+if test "$disable_http" = "yes"; then
   # without HTTP nghttp2 is no use
   OPT_H2="no"
 fi
@@ -3048,7 +3048,7 @@ case "$OPT_H2" in
     ;;
 esac
 
-if test X"$want_nghttp2" != Xno; then
+if test "$want_nghttp2" != "no"; then
   dnl backup the pre-nghttp2 variables
   CLEANLDFLAGS="$LDFLAGS"
   CLEANLDFLAGSPC="$LDFLAGSPC"
@@ -3071,12 +3071,12 @@ if test X"$want_nghttp2" != Xno; then
     AC_MSG_NOTICE([-L is $LD_H2])
 
     DIR_H2=`echo $LD_H2 | $SED -e 's/^-L//'`
-  elif test x"$want_nghttp2_path" != x; then
+  elif test -n "$want_nghttp2_path"; then
     LIB_H2="-lnghttp2"
     LD_H2=-L${want_nghttp2_path}/lib$libsuff
     CPP_H2=-I${want_nghttp2_path}/include
     DIR_H2=${want_nghttp2_path}/lib$libsuff
-  elif test X"$want_nghttp2" != Xdefault; then
+  elif test "$want_nghttp2" != "default"; then
     dnl no nghttp2 pkg-config found and no custom directory specified,
     dnl deal with it
     AC_MSG_ERROR([--with-nghttp2 was specified but could not find libnghttp2 pkg-config file.])
@@ -3118,7 +3118,7 @@ dnl **********************************************************************
 
 OPT_TCP2="no"
 
-if test "x$disable_http" = "xyes"; then
+if test "$disable_http" = "yes"; then
   # without HTTP, ngtcp2 is no use
   OPT_TCP2="no"
 fi
@@ -3145,7 +3145,7 @@ case "$OPT_TCP2" in
 esac
 
 curl_tcp2_msg="no      (--with-ngtcp2)"
-if test X"$want_tcp2" != Xno; then
+if test "$want_tcp2" != "no"; then
 
   if test "$QUIC_ENABLED" != "yes"; then
     AC_MSG_ERROR([the detected TLS library does not support QUIC, making --with-ngtcp2 a no-no])
@@ -3177,7 +3177,7 @@ if test X"$want_tcp2" != Xno; then
     CPPFLAGS="$CPPFLAGS $CPP_TCP2"
     LIBS="$LIB_TCP2 $LIBS"
 
-    if test "x$cross_compiling" != "xyes"; then
+    if test "$cross_compiling" != "yes"; then
       DIR_TCP2=`echo $LD_TCP2 | $SED -e 's/^-L//'`
     fi
     AC_CHECK_LIB(ngtcp2, ngtcp2_conn_client_new_versioned,
@@ -3200,7 +3200,7 @@ if test X"$want_tcp2" != Xno; then
 
   else
     dnl no ngtcp2 pkg-config found, deal with it
-    if test X"$want_tcp2" != Xdefault; then
+    if test "$want_tcp2" != "default"; then
       dnl To avoid link errors, we do not allow --with-ngtcp2 without
       dnl a pkgconfig file
       AC_MSG_ERROR([--with-ngtcp2 was specified but could not find ngtcp2 pkg-config file.])
@@ -3208,7 +3208,8 @@ if test X"$want_tcp2" != Xno; then
   fi
 fi
 
-if test "x$USE_NGTCP2" = "x1" -a "x$OPENSSL_ENABLED" = "x1" -a "$HAVE_LIBRESSL" = "1"; then
+if test "$USE_NGTCP2" = "1" && test "$OPENSSL_ENABLED" = "1" && test "$HAVE_LIBRESSL" = "1"; then
+
   dnl backup the pre-ngtcp2_crypto_libressl variables
   CLEANLDFLAGS="$LDFLAGS"
   CLEANLDFLAGSPC="$LDFLAGSPC"
@@ -3235,7 +3236,7 @@ if test "x$USE_NGTCP2" = "x1" -a "x$OPENSSL_ENABLED" = "x1" -a "$HAVE_LIBRESSL"
     CPPFLAGS="$CPPFLAGS $CPP_NGTCP2_CRYPTO_LIBRESSL"
     LIBS="$LIB_NGTCP2_CRYPTO_LIBRESSL $LIBS"
 
-    if test "x$cross_compiling" != "xyes"; then
+    if test "$cross_compiling" != "yes"; then
       DIR_NGTCP2_CRYPTO_LIBRESSL=`echo $LD_NGTCP2_CRYPTO_LIBRESSL | $SED -e 's/^-L//'`
     fi
     AC_CHECK_LIB(ngtcp2_crypto_libressl, ngtcp2_crypto_recv_client_initial_cb,
@@ -3257,7 +3258,7 @@ if test "x$USE_NGTCP2" = "x1" -a "x$OPENSSL_ENABLED" = "x1" -a "$HAVE_LIBRESSL"
 
   else
     dnl no ngtcp2_crypto_libressl pkg-config found, deal with it
-    if test X"$want_tcp2" != Xdefault; then
+    if test "$want_tcp2" != "default"; then
       dnl To avoid link errors, we do not allow --with-ngtcp2 without
       dnl a pkgconfig file
       AC_MSG_WARN([--with-ngtcp2 was specified but could not find ngtcp2_crypto_libressl pkg-config file.])
@@ -3267,8 +3268,9 @@ if test "x$USE_NGTCP2" = "x1" -a "x$OPENSSL_ENABLED" = "x1" -a "$HAVE_LIBRESSL"
   fi
 fi
 
-if test "x$USE_NGTCP2" = "x1" -a "x$OPENSSL_ENABLED" = "x1" -a "$HAVE_LIBRESSL" != "1" -a \
-   "x$OPENSSL_IS_BORINGSSL" != "x1" -a "x$OPENSSL_QUIC_API2" != "x1"; then
+if test "$USE_NGTCP2" = "1" && test "$OPENSSL_ENABLED" = "1" && test "$OPENSSL_IS_BORINGSSL" != "1" &&
+   test "$OPENSSL_QUIC_API2" != "1"; then
+
   dnl backup the pre-ngtcp2_crypto_quictls variables
   CLEANLDFLAGS="$LDFLAGS"
   CLEANLDFLAGSPC="$LDFLAGSPC"
@@ -3295,7 +3297,7 @@ if test "x$USE_NGTCP2" = "x1" -a "x$OPENSSL_ENABLED" = "x1" -a "$HAVE_LIBRESSL"
     CPPFLAGS="$CPPFLAGS $CPP_NGTCP2_CRYPTO_QUICTLS"
     LIBS="$LIB_NGTCP2_CRYPTO_QUICTLS $LIBS"
 
-    if test "x$cross_compiling" != "xyes"; then
+    if test "$cross_compiling" != "yes"; then
       DIR_NGTCP2_CRYPTO_QUICTLS=`echo $LD_NGTCP2_CRYPTO_QUICTLS | $SED -e 's/^-L//'`
     fi
     AC_CHECK_LIB(ngtcp2_crypto_quictls, ngtcp2_crypto_recv_client_initial_cb,
@@ -3317,7 +3319,7 @@ if test "x$USE_NGTCP2" = "x1" -a "x$OPENSSL_ENABLED" = "x1" -a "$HAVE_LIBRESSL"
 
   else
     dnl no ngtcp2_crypto_quictls pkg-config found, deal with it
-    if test X"$want_tcp2" != Xdefault; then
+    if test "$want_tcp2" != "default"; then
       dnl To avoid link errors, we do not allow --with-ngtcp2 without
       dnl a pkgconfig file
       AC_MSG_ERROR([--with-ngtcp2 was specified but could not find ngtcp2_crypto_quictls pkg-config file.])
@@ -3325,8 +3327,9 @@ if test "x$USE_NGTCP2" = "x1" -a "x$OPENSSL_ENABLED" = "x1" -a "$HAVE_LIBRESSL"
   fi
 fi
 
-if test "x$USE_NGTCP2" = "x1" -a "x$OPENSSL_ENABLED" = "x1" -a \
-   "x$OPENSSL_IS_BORINGSSL" != "x1" -a "x$OPENSSL_QUIC_API2" = "x1"; then
+if test "$USE_NGTCP2" = "1" && test "$OPENSSL_ENABLED" = "1" && test "$OPENSSL_IS_BORINGSSL" != "1" &&
+   test "$OPENSSL_QUIC_API2" = "1"; then
+
   dnl backup the pre-ngtcp2_crypto_ossl variables
   CLEANLDFLAGS="$LDFLAGS"
   CLEANLDFLAGSPC="$LDFLAGSPC"
@@ -3353,7 +3356,7 @@ if test "x$USE_NGTCP2" = "x1" -a "x$OPENSSL_ENABLED" = "x1" -a \
     CPPFLAGS="$CPPFLAGS $CPP_NGTCP2_CRYPTO_OSSL"
     LIBS="$LIB_NGTCP2_CRYPTO_OSSL $LIBS"
 
-    if test "x$cross_compiling" != "xyes"; then
+    if test "$cross_compiling" != "yes"; then
       DIR_NGTCP2_CRYPTO_OSSL=`echo $LD_NGTCP2_CRYPTO_OSSL | $SED -e 's/^-L//'`
     fi
     AC_CHECK_LIB(ngtcp2_crypto_ossl, ngtcp2_crypto_recv_client_initial_cb,
@@ -3376,7 +3379,7 @@ if test "x$USE_NGTCP2" = "x1" -a "x$OPENSSL_ENABLED" = "x1" -a \
 
   else
     dnl no ngtcp2_crypto_ossl pkg-config found, deal with it
-    if test X"$want_tcp2" != Xdefault; then
+    if test "$want_tcp2" != "default"; then
       dnl To avoid link errors, we do not allow --with-ngtcp2 without
       dnl a pkgconfig file
       AC_MSG_ERROR([--with-ngtcp2 was specified but could not find ngtcp2_crypto_ossl pkg-config file.])
@@ -3384,7 +3387,8 @@ if test "x$USE_NGTCP2" = "x1" -a "x$OPENSSL_ENABLED" = "x1" -a \
   fi
 fi
 
-if test "x$USE_NGTCP2" = "x1" -a "x$OPENSSL_ENABLED" = "x1" -a "x$OPENSSL_IS_BORINGSSL" = "x1"; then
+if test "$USE_NGTCP2" = "1" && test "$OPENSSL_ENABLED" = "1" && test "$OPENSSL_IS_BORINGSSL" = "1"; then
+
   dnl backup the pre-ngtcp2_crypto_boringssl variables
   CLEANLDFLAGS="$LDFLAGS"
   CLEANLDFLAGSPC="$LDFLAGSPC"
@@ -3411,7 +3415,7 @@ if test "x$USE_NGTCP2" = "x1" -a "x$OPENSSL_ENABLED" = "x1" -a "x$OPENSSL_IS_BOR
     CPPFLAGS="$CPPFLAGS $CPP_NGTCP2_CRYPTO_BORINGSSL"
     LIBS="$LIB_NGTCP2_CRYPTO_BORINGSSL $LIBS"
 
-    if test "x$cross_compiling" != "xyes"; then
+    if test "$cross_compiling" != "yes"; then
       DIR_NGTCP2_CRYPTO_BORINGSSL=`echo $LD_NGTCP2_CRYPTO_BORINGSSL | $SED -e 's/^-L//'`
     fi
     AC_CHECK_LIB(ngtcp2_crypto_boringssl, ngtcp2_crypto_recv_client_initial_cb,
@@ -3433,7 +3437,7 @@ if test "x$USE_NGTCP2" = "x1" -a "x$OPENSSL_ENABLED" = "x1" -a "x$OPENSSL_IS_BOR
 
   else
     dnl no ngtcp2_crypto_boringssl pkg-config found, deal with it
-    if test X"$want_tcp2" != Xdefault; then
+    if test "$want_tcp2" != "default"; then
       dnl To avoid link errors, we do not allow --with-ngtcp2 without
       dnl a pkgconfig file
       AC_MSG_ERROR([--with-ngtcp2 was specified but could not find ngtcp2_crypto_boringssl pkg-config file.])
@@ -3441,7 +3445,7 @@ if test "x$USE_NGTCP2" = "x1" -a "x$OPENSSL_ENABLED" = "x1" -a "x$OPENSSL_IS_BOR
   fi
 fi
 
-if test "x$USE_NGTCP2" = "x1" -a "x$GNUTLS_ENABLED" = "x1"; then
+if test "$USE_NGTCP2" = "1" && test "$GNUTLS_ENABLED" = "1"; then
   dnl backup the pre-ngtcp2_crypto_gnutls variables
   CLEANLDFLAGS="$LDFLAGS"
   CLEANLDFLAGSPC="$LDFLAGSPC"
@@ -3468,7 +3472,7 @@ if test "x$USE_NGTCP2" = "x1" -a "x$GNUTLS_ENABLED" = "x1"; then
     CPPFLAGS="$CPPFLAGS $CPP_NGTCP2_CRYPTO_GNUTLS"
     LIBS="$LIB_NGTCP2_CRYPTO_GNUTLS $LIBS"
 
-    if test "x$cross_compiling" != "xyes"; then
+    if test "$cross_compiling" != "yes"; then
       DIR_NGTCP2_CRYPTO_GNUTLS=`echo $LD_NGTCP2_CRYPTO_GNUTLS | $SED -e 's/^-L//'`
     fi
     AC_CHECK_LIB(ngtcp2_crypto_gnutls, ngtcp2_crypto_recv_client_initial_cb,
@@ -3490,7 +3494,7 @@ if test "x$USE_NGTCP2" = "x1" -a "x$GNUTLS_ENABLED" = "x1"; then
 
   else
     dnl no ngtcp2_crypto_gnutls pkg-config found, deal with it
-    if test X"$want_tcp2" != Xdefault; then
+    if test "$want_tcp2" != "default"; then
       dnl To avoid link errors, we do not allow --with-ngtcp2 without
       dnl a pkgconfig file
       AC_MSG_ERROR([--with-ngtcp2 was specified but could not find ngtcp2_crypto_gnutls pkg-config file.])
@@ -3498,7 +3502,7 @@ if test "x$USE_NGTCP2" = "x1" -a "x$GNUTLS_ENABLED" = "x1"; then
   fi
 fi
 
-if test "x$USE_NGTCP2" = "x1" -a "x$WOLFSSL_ENABLED" = "x1"; then
+if test "$USE_NGTCP2" = "1" && test "$WOLFSSL_ENABLED" = "1"; then
   dnl backup the pre-ngtcp2_crypto_wolfssl variables
   CLEANLDFLAGS="$LDFLAGS"
   CLEANLDFLAGSPC="$LDFLAGSPC"
@@ -3525,7 +3529,7 @@ if test "x$USE_NGTCP2" = "x1" -a "x$WOLFSSL_ENABLED" = "x1"; then
     CPPFLAGS="$CPPFLAGS $CPP_NGTCP2_CRYPTO_WOLFSSL"
     LIBS="$LIB_NGTCP2_CRYPTO_WOLFSSL $LIBS"
 
-    if test "x$cross_compiling" != "xyes"; then
+    if test "$cross_compiling" != "yes"; then
       DIR_NGTCP2_CRYPTO_WOLFSSL=`echo $LD_NGTCP2_CRYPTO_WOLFSSL | $SED -e 's/^-L//'`
     fi
     AC_CHECK_LIB(ngtcp2_crypto_wolfssl, ngtcp2_crypto_recv_client_initial_cb,
@@ -3547,7 +3551,7 @@ if test "x$USE_NGTCP2" = "x1" -a "x$WOLFSSL_ENABLED" = "x1"; then
 
   else
     dnl no ngtcp2_crypto_wolfssl pkg-config found, deal with it
-    if test X"$want_tcp2" != Xdefault; then
+    if test "$want_tcp2" != "default"; then
       dnl To avoid link errors, we do not allow --with-ngtcp2 without
       dnl a pkgconfig file
       AC_MSG_ERROR([--with-ngtcp2 was specified but could not find ngtcp2_crypto_wolfssl pkg-config file.])
@@ -3561,7 +3565,7 @@ dnl **********************************************************************
 
 OPT_OPENSSL_QUIC="no"
 
-if test "x$disable_http" = "xyes" -o "x$OPENSSL_ENABLED" != "x1"; then
+if test "$disable_http" = "yes" || test "$OPENSSL_ENABLED" != "1"; then
   # without HTTP or without openssl, no use
   OPT_OPENSSL_QUIC="no"
 fi
@@ -3582,12 +3586,12 @@ case "$OPT_OPENSSL_QUIC" in
 esac
 
 curl_openssl_quic_msg="no      (--with-openssl-quic)"
-if test "x$want_openssl_quic" = "xyes"; then
+if test "$want_openssl_quic" = "yes"; then
 
-  if test "$USE_NGTCP2" = 1; then
+  if test "$USE_NGTCP2" = "1"; then
     AC_MSG_ERROR([--with-openssl-quic and --with-ngtcp2 are mutually exclusive])
   fi
-  if test "$have_openssl_quic" != 1; then
+  if test "$have_openssl_quic" != "1"; then
     AC_MSG_ERROR([--with-openssl-quic requires quic support and OpenSSL >= 3.3.0])
   fi
   AC_DEFINE(USE_OPENSSL_QUIC, 1, [if openssl QUIC is in use])
@@ -3600,7 +3604,7 @@ dnl **********************************************************************
 
 OPT_NGHTTP3="yes"
 
-if test "x$USE_NGTCP2" != "x1" -a "x$USE_OPENSSL_QUIC" != "x1"; then
+if test "$USE_NGTCP2" != "1" && test "$USE_OPENSSL_QUIC" != "1"; then
   # without ngtcp2 or openssl quic, nghttp3 is of no use for us
   OPT_NGHTTP3="no"
   want_nghttp3="no"
@@ -3628,9 +3632,9 @@ case "$OPT_NGHTTP3" in
 esac
 
 curl_http3_msg="no      (--with-nghttp3)"
-if test X"$want_nghttp3" != Xno; then
+if test "$want_nghttp3" != "no"; then
 
-  if test "x$USE_NGTCP2" != "x1" -a "x$USE_OPENSSL_QUIC" != "x1"; then
+  if test "$USE_NGTCP2" != "1" && test "$USE_OPENSSL_QUIC" != "1"; then
     # without ngtcp2 or openssl quic, nghttp3 is of no use for us
     AC_MSG_ERROR([nghttp3 enabled without a QUIC library; enable ngtcp2 or OpenSSL-QUIC])
   fi
@@ -3661,7 +3665,7 @@ if test X"$want_nghttp3" != Xno; then
     CPPFLAGS="$CPPFLAGS $CPP_NGHTTP3"
     LIBS="$LIB_NGHTTP3 $LIBS"
 
-    if test "x$cross_compiling" != "xyes"; then
+    if test "$cross_compiling" != "yes"; then
       DIR_NGHTTP3=`echo $LD_NGHTTP3 | $SED -e 's/^-L//'`
     fi
     AC_CHECK_LIB(nghttp3, nghttp3_conn_client_new_versioned,
@@ -3684,7 +3688,7 @@ if test X"$want_nghttp3" != Xno; then
 
   else
     dnl no nghttp3 pkg-config found, deal with it
-    if test X"$want_nghttp3" != Xdefault; then
+    if test "$want_nghttp3" != "default"; then
       dnl To avoid link errors, we do not allow --with-nghttp3 without
       dnl a pkgconfig file
       AC_MSG_ERROR([--with-nghttp3 was specified but could not find nghttp3 pkg-config file.])
@@ -3696,7 +3700,7 @@ dnl **********************************************************************
 dnl Check for ngtcp2 and nghttp3 (HTTP/3 with ngtcp2 + nghttp3)
 dnl **********************************************************************
 
-if test "x$USE_NGTCP2" = "x1" -a "x$USE_NGHTTP3" = "x1"; then
+if test "$USE_NGTCP2" = "1" && test "$USE_NGHTTP3" = "1"; then
   USE_NGTCP2_H3=1
   AC_MSG_NOTICE([HTTP3 support is experimental])
   curl_h3_msg="enabled (ngtcp2 + nghttp3)"
@@ -3706,7 +3710,7 @@ dnl **********************************************************************
 dnl Check for OpenSSL and nghttp3 (HTTP/3 with nghttp3 using OpenSSL QUIC)
 dnl **********************************************************************
 
-if test "x$USE_OPENSSL_QUIC" = "x1" -a "x$USE_NGHTTP3" = "x1"; then
+if test "$USE_OPENSSL_QUIC" = "1" && test "$USE_NGHTTP3" = "1"; then
   experimental="$experimental HTTP3"
   USE_OPENSSL_H3=1
   AC_MSG_NOTICE([HTTP3 support is experimental])
@@ -3719,7 +3723,7 @@ dnl **********************************************************************
 
 OPT_QUICHE="no"
 
-if test "x$disable_http" = "xyes" -o "x$USE_NGTCP" = "x1"; then
+if test "$disable_http" = "yes" || test "$USE_NGTCP" = "1"; then
   # without HTTP or with ngtcp2, quiche is no use
   OPT_QUICHE="no"
 fi
@@ -3745,13 +3749,13 @@ case "$OPT_QUICHE" in
     ;;
 esac
 
-if test X"$want_quiche" != Xno; then
+if test "$want_quiche" != "no"; then
 
   if test "$QUIC_ENABLED" != "yes"; then
     AC_MSG_ERROR([the detected TLS library does not support QUIC, making --with-quiche a no-no])
   fi
 
-  if test "$NGHTTP3_ENABLED" = 1; then
+  if test "$NGHTTP3_ENABLED" = "1"; then
     AC_MSG_ERROR([--with-quiche and --with-ngtcp2 are mutually exclusive])
   fi
 
@@ -3781,7 +3785,7 @@ if test X"$want_quiche" != Xno; then
     CPPFLAGS="$CPPFLAGS $CPP_QUICHE"
     LIBS="$LIB_QUICHE $LIBS"
 
-    if test "x$cross_compiling" != "xyes"; then
+    if test "$cross_compiling" != "yes"; then
       DIR_QUICHE=`echo $LD_QUICHE | $SED -e 's/^-L//'`
     fi
     AC_CHECK_LIB(quiche, quiche_conn_send_ack_eliciting,
@@ -3809,7 +3813,7 @@ if test X"$want_quiche" != Xno; then
     )
   else
     dnl no quiche pkg-config found, deal with it
-    if test X"$want_quiche" != Xdefault; then
+    if test "$want_quiche" != "default"; then
       dnl To avoid link errors, we do not allow --with-quiche without
       dnl a pkgconfig file
       AC_MSG_ERROR([--with-quiche was specified but could not find quiche pkg-config file.])
@@ -3843,8 +3847,8 @@ case "$OPT_LIBUV" in
     ;;
 esac
 
-if test X"$want_libuv" != Xno; then
-  if test x$want_debug != xyes; then
+if test "$want_libuv" != "no"; then
+  if test "$want_debug" != "yes"; then
     AC_MSG_ERROR([Using libuv without debug support enabled is useless])
   fi
 
@@ -3874,7 +3878,7 @@ if test X"$want_libuv" != Xno; then
     CPPFLAGS="$CPPFLAGS $CPP_LIBUV"
     LIBS="$LIB_LIBUV $LIBS"
 
-    if test "x$cross_compiling" != "xyes"; then
+    if test "$cross_compiling" != "yes"; then
       DIR_LIBUV=`echo $LD_LIBUV | $SED -e 's/^-L//'`
     fi
     AC_CHECK_LIB(uv, uv_default_loop,
@@ -3897,7 +3901,7 @@ if test X"$want_libuv" != Xno; then
 
   else
     dnl no libuv pkg-config found, deal with it
-    if test X"$want_libuv" != Xdefault; then
+    if test "$want_libuv" != "default"; then
       dnl To avoid link errors, we do not allow --with-libuv without
       dnl a pkgconfig file
       AC_MSG_ERROR([--with-libuv was specified but could not find libuv pkg-config file.])
@@ -3930,11 +3934,11 @@ case "$OPT_ZSH_FPATH" in
     AC_SUBST(ZSH_FUNCTIONS_DIR)
     ;;
 esac
-if test -z "$PERL" -a x"$ZSH_FUNCTIONS_DIR" != x; then
+if test -z "$PERL" && test -n "$ZSH_FUNCTIONS_DIR"; then
   AC_MSG_WARN([perl was not found. Will not install zsh completions.])
   ZSH_FUNCTIONS_DIR=''
 fi
-AM_CONDITIONAL(USE_ZSH_COMPLETION, test x"$ZSH_FUNCTIONS_DIR" != x)
+AM_CONDITIONAL(USE_ZSH_COMPLETION, test -n "$ZSH_FUNCTIONS_DIR")
 
 dnl **********************************************************************
 dnl Check for fish completion path
@@ -3965,11 +3969,11 @@ case "$OPT_FISH_FPATH" in
     AC_SUBST(FISH_FUNCTIONS_DIR)
     ;;
 esac
-if test -z "$PERL" -a x"$FISH_FUNCTIONS_DIR" != x; then
+if test -z "$PERL" && test -n "$FISH_FUNCTIONS_DIR"; then
   AC_MSG_WARN([perl was not found. Will not install fish completions.])
   FISH_FUNCTIONS_DIR=''
 fi
-AM_CONDITIONAL(USE_FISH_COMPLETION, test x"$FISH_FUNCTIONS_DIR" != x)
+AM_CONDITIONAL(USE_FISH_COMPLETION, test -n "$FISH_FUNCTIONS_DIR")
 
 dnl Now check for the most basic headers. Then we can use these
 dnl ones as default-headers when checking for the rest!
@@ -4067,7 +4071,7 @@ AC_CHECK_TYPE(long long,
     [Define to 1 if the compiler supports the 'long long' data type.])]
 )
 
-if test ${ac_cv_sizeof_curl_off_t} -lt 8; then
+if test "$ac_cv_sizeof_curl_off_t" -lt 8; then
   AC_MSG_ERROR([64-bit curl_off_t is required])
 fi
 
@@ -4088,7 +4092,7 @@ AC_CHECK_TYPE([bool],[
 #endif
 ])
 
-if test "$curl_cv_native_windows" != 'yes'; then
+if test "$curl_cv_native_windows" != "yes"; then
   # check for sa_family_t
   AC_CHECK_TYPE(sa_family_t,
     AC_DEFINE(HAVE_SA_FAMILY_T, 1, [Define to 1 if symbol `sa_family_t' exists]),,
@@ -4203,7 +4207,7 @@ AC_CHECK_FUNCS([\
   utimes \
 ])
 
-if test "$curl_cv_native_windows" = 'yes'; then
+if test "$curl_cv_native_windows" = "yes"; then
   AC_MSG_CHECKING([for if_nametoindex on Windows])
   AC_LINK_IFELSE([
     AC_LANG_PROGRAM([[
@@ -4236,7 +4240,7 @@ else
 fi
 
 AC_CHECK_FUNCS([setmode])
-if test "$curl_cv_native_windows" = 'yes' -o "$curl_cv_cygwin" = 'yes'; then
+if test "$curl_cv_native_windows" = "yes" || test "$curl_cv_cygwin" = "yes"; then
   AC_CHECK_FUNCS([_setmode])
 fi
 
@@ -4244,7 +4248,7 @@ if test -z "$ssl_backends"; then
   AC_CHECK_FUNCS([arc4random])
 fi
 
-if test "$curl_cv_native_windows" != 'yes'; then
+if test "$curl_cv_native_windows" != "yes"; then
   AC_CHECK_FUNCS([fseeko])
 
   dnl On Android, the only way to know if fseeko can be used is to see if it is
@@ -4260,7 +4264,7 @@ fi
 CURL_CHECK_NONBLOCKING_SOCKET
 
 dnl set variable for use in automakefile(s)
-AM_CONDITIONAL(BUILD_DOCS, test x"$BUILD_DOCS" = x1)
+AM_CONDITIONAL(BUILD_DOCS, test "$BUILD_DOCS" = "1")
 
 dnl *************************************************************************
 dnl If the manual variable still is set, then we go with providing a built-in
@@ -4271,12 +4275,12 @@ if test "$USE_MANUAL" = "1"; then
 fi
 
 dnl set variable for use in automakefile(s)
-AM_CONDITIONAL(USE_MANUAL, test x"$USE_MANUAL" = x1)
+AM_CONDITIONAL(USE_MANUAL, test "$USE_MANUAL" = "1")
 
 CURL_CHECK_LIB_ARES
 CURL_CHECK_OPTION_THREADED_RESOLVER
 
-if test "$ipv6" = yes -a "$curl_cv_apple" = 'yes'; then
+if test "$ipv6" = "yes" && test "$curl_cv_apple" = "yes"; then
   CURL_DARWIN_SYSTEMCONFIGURATION
 fi
 
@@ -4321,7 +4325,7 @@ if test "$want_threaded_resolver" = "yes" && test "$USE_THREADS_WIN32" != "1"; t
           *-ibm-aix*)
             dnl Check if compiler is xlC
             COMPILER_VERSION=`"$CC" -qversion 2>/dev/null`
-            if test x"$COMPILER_VERSION" = "x"; then
+            if test -z "$COMPILER_VERSION"; then
               CFLAGS="$CFLAGS -pthread"
             else
               CFLAGS="$CFLAGS -qthreaded"
@@ -4340,7 +4344,7 @@ if test "$want_threaded_resolver" = "yes" && test "$USE_THREADS_WIN32" != "1"; t
                      [ CFLAGS="$save_CFLAGS"])
       fi
 
-      if test "x$USE_THREADS_POSIX" = "x1"; then
+      if test "$USE_THREADS_POSIX" = "1"; then
         AC_DEFINE(USE_THREADS_POSIX, 1, [if you want POSIX threaded DNS lookup])
         curl_res_msg="POSIX threaded"
       fi
@@ -4348,7 +4352,7 @@ if test "$want_threaded_resolver" = "yes" && test "$USE_THREADS_WIN32" != "1"; t
 fi
 
 dnl Did we find a threading option?
-if test "$want_threaded_resolver" != "no" -a "x$USE_THREADS_POSIX" != "x1" -a "x$USE_THREADS_WIN32" != "x1"; then
+if test "$want_threaded_resolver" != "no" && test "$USE_THREADS_POSIX" != "1" && test "$USE_THREADS_WIN32" != "1"; then
   AC_MSG_ERROR([Threaded resolver enabled but no thread library found])
 fi
 
@@ -4400,7 +4404,7 @@ AS_HELP_STRING([--disable-verbose],[Disable verbose strings]),
     AC_MSG_RESULT(yes)
 )
 
-if test "$curl_cv_winuwp" != 'yes'; then
+if test "$curl_cv_winuwp" != "yes"; then
   dnl ************************************************************
   dnl enable SSPI support
   dnl
@@ -4421,7 +4425,7 @@ if test "$curl_cv_winuwp" != 'yes'; then
       fi
       ;;
     *)
-      if test "x$SCHANNEL_ENABLED" = "x1"; then
+      if test "$SCHANNEL_ENABLED" = "1"; then
         # --with-schannel implies --enable-sspi
         AC_MSG_RESULT(yes)
       else
@@ -4429,7 +4433,7 @@ if test "$curl_cv_winuwp" != 'yes'; then
       fi
       ;;
     esac ],
-      if test "x$SCHANNEL_ENABLED" = "x1"; then
+      if test "$SCHANNEL_ENABLED" = "1"; then
         # --with-schannel implies --enable-sspi
         AC_MSG_RESULT(yes)
       else
@@ -4437,7 +4441,7 @@ if test "$curl_cv_winuwp" != 'yes'; then
       fi
   )
 
-  if test "x$USE_WINDOWS_SSPI" = "x1"; then
+  if test "$USE_WINDOWS_SSPI" = "1"; then
     LIBS="-lsecur32 $LIBS"
   fi
 fi
@@ -4599,7 +4603,7 @@ AS_HELP_STRING([--disable-tls-srp],[Disable TLS-SRP authentication]),
     want_tls_srp=yes
 )
 
-if test "$want_tls_srp" = "yes" && ( test "x$HAVE_GNUTLS_SRP" = "x1" || test "x$HAVE_OPENSSL_SRP" = "x1"); then
+if test "$want_tls_srp" = "yes" && (test "$HAVE_GNUTLS_SRP" = "1" || test "$HAVE_OPENSSL_SRP" = "1"); then
   AC_DEFINE(USE_TLS_SRP, 1, [Use TLS-SRP authentication])
   USE_TLS_SRP=1
   curl_tls_srp_msg="enabled"
@@ -4626,8 +4630,8 @@ AS_HELP_STRING([--disable-unix-sockets],[Disable Unix domain sockets]),
     want_unix_sockets=auto
     ]
 )
-if test "x$want_unix_sockets" != "xno"; then
-  if test "x$curl_cv_native_windows" = "xyes"; then
+if test "$want_unix_sockets" != "no"; then
+  if test "$curl_cv_native_windows" = "yes"; then
     USE_UNIX_SOCKETS=1
     AC_DEFINE(USE_UNIX_SOCKETS, 1, [Use Unix domain sockets])
     curl_unix_sockets_msg="enabled"
@@ -4637,7 +4641,7 @@ if test "x$want_unix_sockets" != "xno"; then
       USE_UNIX_SOCKETS=1
       curl_unix_sockets_msg="enabled"
     ], [
-      if test "x$want_unix_sockets" = "xyes"; then
+      if test "$want_unix_sockets" = "yes"; then
         AC_MSG_ERROR([--enable-unix-sockets is not available on this platform!])
       fi
     ], [
@@ -4774,12 +4778,12 @@ AS_HELP_STRING([--disable-form-api],[Disable form API support]),
     ;;
   *)
     AC_MSG_RESULT(yes)
-    test "$enable_mime" = no &&
+    test "x$enable_mime" = "xno" &&
       AC_MSG_ERROR(MIME support needs to be enabled in order to enable form API support)
     ;;
   esac ],
 [
-  if test "$enable_mime" = no; then
+  if test "x$enable_mime" = "xno"; then
     enable_form_api=no
     AC_MSG_RESULT(no)
     AC_DEFINE(CURL_DISABLE_FORM_API, 1, [disable form API])
@@ -4968,7 +4972,7 @@ else
   hsts="no"
 fi
 
-if test "x$hsts" != "xyes"; then
+if test "$hsts" != "yes"; then
   curl_hsts_msg="no      (--enable-hsts)";
   AC_DEFINE(CURL_DISABLE_HSTS, 1, [disable alt-svc])
 fi
@@ -4977,7 +4981,7 @@ fi
 dnl *************************************************************
 dnl check whether ECH support, if desired, is actually available
 dnl
-if test "x$want_ech" != "xno"; then
+if test "$want_ech" != "no"; then
   AC_MSG_CHECKING([whether ECH support is available])
 
   dnl assume NOT and look for sufficient condition
@@ -4988,25 +4992,25 @@ if test "x$want_ech" != "xno"; then
   ECH_SUPPORT=''
 
   dnl check for OpenSSL equivalent
-  if test "x$OPENSSL_ENABLED" = "x1"; then
+  if test "$OPENSSL_ENABLED" = "1"; then
     AC_CHECK_FUNCS(SSL_set1_ech_config_list,
       ECH_SUPPORT="$ECH_SUPPORT OpenSSL"
       ECH_ENABLED_OPENSSL=1)
   fi
-  if test "x$WOLFSSL_ENABLED" = "x1"; then
+  if test "$WOLFSSL_ENABLED" = "1"; then
     AC_CHECK_FUNCS(wolfSSL_CTX_GenerateEchConfig,
       ECH_SUPPORT="$ECH_SUPPORT wolfSSL"
       ECH_ENABLED_WOLFSSL=1)
   fi
-  if test "x$RUSTLS_ENABLED" = "x1"; then
+  if test "$RUSTLS_ENABLED" = "1"; then
     ECH_SUPPORT="$ECH_SUPPORT rustls-ffi"
     ECH_ENABLED_RUSTLS=1
   fi
 
   dnl now deal with whatever we found
-  if test "x$ECH_ENABLED_OPENSSL" = "x1" -o \
-          "x$ECH_ENABLED_WOLFSSL" = "x1" -o \
-          "x$ECH_ENABLED_RUSTLS" = "x1"; then
+  if test "$ECH_ENABLED_OPENSSL" = "1" ||
+     test "$ECH_ENABLED_WOLFSSL" = "1" ||
+     test "$ECH_ENABLED_RUSTLS" = "1"; then
     AC_DEFINE(USE_ECH, 1, [if ECH support is available])
     AC_MSG_RESULT(ECH support available via:$ECH_SUPPORT)
     experimental="$experimental ECH"
@@ -5022,7 +5026,7 @@ AC_MSG_CHECKING([whether to enable HTTPS-RR support])
 dnl *************************************************************
 dnl check whether HTTPSRR support if desired
 dnl
-if test "x$want_httpsrr" != "xno"; then
+if test "$want_httpsrr" != "no"; then
   AC_MSG_RESULT([yes])
   AC_DEFINE(USE_HTTPSRR, 1, [enable HTTPS RR support])
   experimental="$experimental HTTPSRR"
@@ -5032,7 +5036,7 @@ else
   # no HTTPSRR wanted
   if test "$want_threaded_resolver" = "yes"; then
     # and using the threaded resolver
-    if test "x$USE_ARES" = "x1"; then
+    if test "$USE_ARES" = "1"; then
       AC_MSG_ERROR([without HTTPS-RR support, asking for both threaded resolver and c-ares support is ambivalent. Please drop one of them.])
     fi
   fi
@@ -5042,11 +5046,11 @@ fi
 dnl *************************************************************
 dnl check whether OpenSSL (lookalikes) have SSL_set0_wbio
 dnl
-if test "x$OPENSSL_ENABLED" = "x1"; then
+if test "$OPENSSL_ENABLED" = "1"; then
   AC_CHECK_FUNCS([SSL_set0_wbio])
 fi
 
-if test "x$CURL_DISABLE_HTTP" != "x1"; then
+if test "$CURL_DISABLE_HTTP" != "1"; then
   dnl *************************************************************
   dnl WebSockets
   dnl
@@ -5061,7 +5065,7 @@ if test "x$CURL_DISABLE_HTTP" != "x1"; then
       CURL_DISABLE_WEBSOCKETS=1
       ;;
     *)
-      if test ${ac_cv_sizeof_curl_off_t} -gt 4; then
+      if test "$ac_cv_sizeof_curl_off_t" -gt 4; then
         AC_MSG_RESULT(yes)
       else
         dnl WebSockets requires >32-bit curl_off_t
@@ -5083,14 +5087,14 @@ fi
 dnl *************************************************************
 dnl check whether experimental SSL Session Im-/Export is enabled
 dnl
-if test "x$want_ssls_export" != "xno"; then
+if test "$want_ssls_export" != "no"; then
   AC_MSG_CHECKING([whether SSL session export support is available])
 
   dnl assume NOT and look for sufficient condition
   SSLS_EXPORT_ENABLED=0
   SSLS_EXPORT_SUPPORT=''
 
-  if test "x$SSL_ENABLED" != "x1"; then
+  if test "$SSL_ENABLED" != "1"; then
     AC_MSG_WARN([--enable-ssls-export ignored: No SSL support])
   else
     SSLS_EXPORT_ENABLED=1
@@ -5139,7 +5143,7 @@ dnl all link targets in given makefile.
 BLANK_AT_MAKETIME=
 AC_SUBST(BLANK_AT_MAKETIME)
 
-AM_CONDITIONAL(CROSSCOMPILING, test x$cross_compiling = xyes)
+AM_CONDITIONAL(CROSSCOMPILING, test "$cross_compiling" = "yes")
 
 dnl yes or no
 ENABLE_SHARED="$enable_shared"
@@ -5155,7 +5159,7 @@ LIBCURL_PC_REQUIRES_PRIVATE=`echo $LIBCURL_PC_REQUIRES_PRIVATE | tr ' ' ','`
 AC_SUBST(LIBCURL_PC_REQUIRES_PRIVATE)
 
 dnl Merge pkg-config private fields into public ones when static-only
-if test "x$enable_shared" = "xno"; then
+if test "$enable_shared" = "no"; then
   LIBCURL_PC_REQUIRES=$LIBCURL_PC_REQUIRES_PRIVATE
   LIBCURL_PC_LIBS=$LIBCURL_PC_LIBS_PRIVATE
 else
@@ -5172,119 +5176,117 @@ dnl For keeping supported features and protocols also in pkg-config file
 dnl since it is more cross-compile friendly than curl-config
 dnl
 
-if test "x$OPENSSL_ENABLED" = "x1"; then
+if test "$OPENSSL_ENABLED" = "1"; then
   SUPPORT_FEATURES="$SUPPORT_FEATURES SSL"
 elif test -n "$SSL_ENABLED"; then
   SUPPORT_FEATURES="$SUPPORT_FEATURES SSL"
 fi
-if test "x$IPV6_ENABLED" = "x1"; then
+if test "$IPV6_ENABLED" = "1"; then
   SUPPORT_FEATURES="$SUPPORT_FEATURES IPv6"
 fi
-if test "x$USE_UNIX_SOCKETS" = "x1"; then
+if test "$USE_UNIX_SOCKETS" = "1"; then
   SUPPORT_FEATURES="$SUPPORT_FEATURES UnixSockets"
 fi
-if test "x$HAVE_LIBZ" = "x1"; then
+if test "$HAVE_LIBZ" = "1"; then
   SUPPORT_FEATURES="$SUPPORT_FEATURES libz"
 fi
-if test "x$HAVE_BROTLI" = "x1"; then
+if test "$HAVE_BROTLI" = "1"; then
   SUPPORT_FEATURES="$SUPPORT_FEATURES brotli"
 fi
-if test "x$HAVE_ZSTD" = "x1"; then
+if test "$HAVE_ZSTD" = "1"; then
   SUPPORT_FEATURES="$SUPPORT_FEATURES zstd"
 fi
-if test "x$USE_ARES" = "x1" -o "x$USE_THREADS_POSIX" = "x1" \
-                            -o "x$USE_THREADS_WIN32" = "x1"; then
+if test "$USE_ARES" = "1" || test "$USE_THREADS_POSIX" = "1" || test "$USE_THREADS_WIN32" = "1"; then
   SUPPORT_FEATURES="$SUPPORT_FEATURES AsynchDNS"
 fi
-if test "x$USE_ARES" = "x1" -a "$want_threaded_resolver" = "yes" -a "x$want_httpsrr" != "xno"; then
+if test "$USE_ARES" = "1" && test "$want_threaded_resolver" = "yes" && test "$want_httpsrr" != "no"; then
   SUPPORT_FEATURES="$SUPPORT_FEATURES asyn-rr"
 fi
-if test "x$IDN_ENABLED" = "x1"; then
+if test "$IDN_ENABLED" = "1"; then
   SUPPORT_FEATURES="$SUPPORT_FEATURES IDN"
 fi
-if test "x$USE_WINDOWS_SSPI" = "x1"; then
+if test "$USE_WINDOWS_SSPI" = "1"; then
   SUPPORT_FEATURES="$SUPPORT_FEATURES SSPI"
 fi
 
-if test "x$HAVE_GSSAPI" = "x1"; then
+if test "$HAVE_GSSAPI" = "1"; then
   SUPPORT_FEATURES="$SUPPORT_FEATURES GSS-API"
 fi
 
-if test "x$curl_psl_msg" = "xenabled"; then
+if test "$curl_psl_msg" = "enabled"; then
   SUPPORT_FEATURES="$SUPPORT_FEATURES PSL"
 fi
 
-if test "x$curl_gsasl_msg" = "xenabled"; then
+if test "$curl_gsasl_msg" = "enabled"; then
   SUPPORT_FEATURES="$SUPPORT_FEATURES gsasl"
 fi
 
-if test "x$enable_altsvc" = "xyes"; then
+if test "$enable_altsvc" = "yes"; then
   SUPPORT_FEATURES="$SUPPORT_FEATURES alt-svc"
 fi
-if test "x$hsts" = "xyes"; then
+if test "$hsts" = "yes"; then
   SUPPORT_FEATURES="$SUPPORT_FEATURES HSTS"
 fi
 
-if test "x$CURL_DISABLE_NEGOTIATE_AUTH" != "x1" -a \
-    \( "x$HAVE_GSSAPI" = "x1" -o "x$USE_WINDOWS_SSPI" = "x1" \); then
+if test "$CURL_DISABLE_NEGOTIATE_AUTH" != "1" && (test "$HAVE_GSSAPI" = "1" || test "$USE_WINDOWS_SSPI" = "1"); then
   SUPPORT_FEATURES="$SUPPORT_FEATURES SPNEGO"
 fi
 
-if test "x$CURL_DISABLE_KERBEROS_AUTH" != "x1" -a \
-    \( "x$HAVE_GSSAPI" = "x1" -o "x$USE_WINDOWS_SSPI" = "x1" \); then
+if test "$CURL_DISABLE_KERBEROS_AUTH" != "1" && (test "$HAVE_GSSAPI" = "1" || test "$USE_WINDOWS_SSPI" = "1"); then
   SUPPORT_FEATURES="$SUPPORT_FEATURES Kerberos"
 fi
 
 use_curl_ntlm_core=no
 
-if test "x$CURL_DISABLE_NTLM" != "x1"; then
-  if test "x$HAVE_DES_ECB_ENCRYPT" = "x1" \
-      -o "x$GNUTLS_ENABLED" = "x1" \
-      -o "x$USE_WIN32_CRYPTO" = "x1" \
-      -o "x$HAVE_WOLFSSL_DES_ECB_ENCRYPT" = "x1" \
-      -o "x$HAVE_MBEDTLS_DES_CRYPT_ECB" = "x1"; then
+if test "$CURL_DISABLE_NTLM" != "1"; then
+  if test "$HAVE_DES_ECB_ENCRYPT" = "1" ||
+     test "$GNUTLS_ENABLED" = "1" ||
+     test "$USE_WIN32_CRYPTO" = "1" ||
+     test "$HAVE_WOLFSSL_DES_ECB_ENCRYPT" = "1" ||
+     test "$HAVE_MBEDTLS_DES_CRYPT_ECB" = "1"; then
     use_curl_ntlm_core=yes
   fi
 
-  if test "x$use_curl_ntlm_core" = "xyes" \
-      -o "x$USE_WINDOWS_SSPI" = "x1"; then
+  if test "$use_curl_ntlm_core" = "yes" ||
+     test "$USE_WINDOWS_SSPI" = "1"; then
     SUPPORT_FEATURES="$SUPPORT_FEATURES NTLM"
   fi
 fi
 
-if test "x$USE_TLS_SRP" = "x1"; then
+if test "$USE_TLS_SRP" = "1"; then
   SUPPORT_FEATURES="$SUPPORT_FEATURES TLS-SRP"
 fi
 
-if test "x$USE_NGHTTP2" = "x1"; then
+if test "$USE_NGHTTP2" = "1"; then
   SUPPORT_FEATURES="$SUPPORT_FEATURES HTTP2"
 fi
 
-if test "x$USE_NGTCP2_H3" = "x1" -o "x$USE_QUICHE" = "x1" \
-    -o "x$USE_OPENSSL_H3" = "x1"; then
-  if test "x$CURL_WITH_MULTI_SSL" = "x1"; then
+if test "$USE_NGTCP2_H3" = "1" ||
+   test "$USE_QUICHE" = "1" ||
+   test "$USE_OPENSSL_H3" = "1"; then
+  if test "$CURL_WITH_MULTI_SSL" = "1"; then
     AC_MSG_ERROR([MultiSSL cannot be enabled with HTTP/3 and vice versa])
   fi
   SUPPORT_FEATURES="$SUPPORT_FEATURES HTTP3"
 fi
 
-if test "x$CURL_WITH_MULTI_SSL" = "x1"; then
+if test "$CURL_WITH_MULTI_SSL" = "1"; then
   SUPPORT_FEATURES="$SUPPORT_FEATURES MultiSSL"
 fi
 
 AC_MSG_CHECKING([if this build supports HTTPS-proxy])
 dnl if not explicitly turned off, HTTPS-proxy comes with some TLS backends
-if test "x$CURL_DISABLE_HTTP" != "x1"; then
-  if test "x$https_proxy" != "xno"; then
-    if test "x$OPENSSL_ENABLED" = "x1" \
-        -o "x$GNUTLS_ENABLED" = "x1" \
-        -o "x$RUSTLS_ENABLED" = "x1" \
-        -o "x$SCHANNEL_ENABLED" = "x1" \
-        -o "x$GNUTLS_ENABLED" = "x1" \
-        -o "x$MBEDTLS_ENABLED" = "x1"; then
+if test "$CURL_DISABLE_HTTP" != "1"; then
+  if test "$https_proxy" != "no"; then
+    if test "$OPENSSL_ENABLED" = "1" ||
+       test "$GNUTLS_ENABLED" = "1" ||
+       test "$RUSTLS_ENABLED" = "1" ||
+       test "$SCHANNEL_ENABLED" = "1" ||
+       test "$GNUTLS_ENABLED" = "1" ||
+       test "$MBEDTLS_ENABLED" = "1"; then
       SUPPORT_FEATURES="$SUPPORT_FEATURES HTTPS-proxy"
       AC_MSG_RESULT([yes])
-    elif test "x$WOLFSSL_ENABLED" = "x1" -a "x$HAVE_WOLFSSL_BIO_NEW" = "x1"; then
+    elif test "$WOLFSSL_ENABLED" = "1" && test "$HAVE_WOLFSSL_BIO_NEW" = "1"; then
       SUPPORT_FEATURES="$SUPPORT_FEATURES HTTPS-proxy"
       AC_MSG_RESULT([yes])
     else
@@ -5297,35 +5299,34 @@ else
   AC_MSG_RESULT([no])
 fi
 
-if test "x$OPENSSL_ENABLED" = "x1" -o -n "$SSL_ENABLED"; then
-  if test "x$ECH_ENABLED" = "x1"; then
+if test "$OPENSSL_ENABLED" = "1" || test -n "$SSL_ENABLED"; then
+  if test "$ECH_ENABLED" = "1"; then
     SUPPORT_FEATURES="$SUPPORT_FEATURES ECH"
   fi
 fi
 
-if test "x$APPLE_SECTRUST_ENABLED" = "x1"; then
+if test "$APPLE_SECTRUST_ENABLED" = "1"; then
   SUPPORT_FEATURES="$SUPPORT_FEATURES AppleSecTrust"
 fi
 
-if test "x$want_httpsrr" != "xno"; then
+if test "$want_httpsrr" != "no"; then
   SUPPORT_FEATURES="$SUPPORT_FEATURES HTTPSRR"
 fi
 
-if test "x$SSLS_EXPORT_ENABLED" = "x1"; then
+if test "$SSLS_EXPORT_ENABLED" = "1"; then
   SUPPORT_FEATURES="$SUPPORT_FEATURES SSLS-EXPORT"
 fi
 
-if test ${ac_cv_sizeof_curl_off_t} -gt 4; then
-  if test ${ac_cv_sizeof_off_t} -gt 4 -o \
-     "$curl_cv_native_windows" = "yes"; then
+if test "$ac_cv_sizeof_curl_off_t" -gt 4; then
+  if test "$ac_cv_sizeof_off_t" -gt 4 ||
+     test "$curl_cv_native_windows" = "yes"; then
     SUPPORT_FEATURES="$SUPPORT_FEATURES Largefile"
   fi
 fi
 
 if test "$tst_atomic" = "yes"; then
   SUPPORT_FEATURES="$SUPPORT_FEATURES threadsafe"
-elif test "x$USE_THREADS_POSIX" = "x1" -a \
-     "x$ac_cv_header_pthread_h" = "xyes"; then
+elif test "$USE_THREADS_POSIX" = "1" && test "$ac_cv_header_pthread_h" = "yes"; then
   SUPPORT_FEATURES="$SUPPORT_FEATURES threadsafe"
 else
   AC_COMPILE_IFELSE([
@@ -5342,16 +5343,16 @@ else
   ])
 fi
 
-if test "x$want_winuni" = "xyes"; then
+if test "$want_winuni" = "yes"; then
   SUPPORT_FEATURES="$SUPPORT_FEATURES Unicode"
 fi
-if test "x$want_debug" = "xyes"; then
+if test "$want_debug" = "yes"; then
   SUPPORT_FEATURES="$SUPPORT_FEATURES Debug"
 fi
-if test "x$want_curldebug" = "xyes"; then
+if test "$want_curldebug" = "yes"; then
   SUPPORT_FEATURES="$SUPPORT_FEATURES TrackMemory"
 fi
-if test "x$CURL_CA_EMBED" != "x"; then
+if test -n "$CURL_CA_EMBED"; then
   SUPPORT_FEATURES="$SUPPORT_FEATURES CAcert"
   CURL_CA_EMBED_msg="$CURL_CA_EMBED"
 else
@@ -5369,93 +5370,92 @@ fi
 AC_SUBST(SUPPORT_FEATURES)
 
 dnl For supported protocols in pkg-config file
-if test "x$CURL_DISABLE_HTTP" != "x1"; then
+if test "$CURL_DISABLE_HTTP" != "1"; then
   SUPPORT_PROTOCOLS="$SUPPORT_PROTOCOLS HTTP"
-  if test "x$SSL_ENABLED" = "x1"; then
+  if test "$SSL_ENABLED" = "1"; then
     SUPPORT_PROTOCOLS="$SUPPORT_PROTOCOLS HTTPS"
   fi
 fi
-if test "x$CURL_DISABLE_FTP" != "x1"; then
+if test "$CURL_DISABLE_FTP" != "1"; then
   SUPPORT_PROTOCOLS="$SUPPORT_PROTOCOLS FTP"
-  if test "x$SSL_ENABLED" = "x1"; then
+  if test "$SSL_ENABLED" = "1"; then
     SUPPORT_PROTOCOLS="$SUPPORT_PROTOCOLS FTPS"
   fi
 fi
-if test "x$CURL_DISABLE_FILE" != "x1"; then
+if test "$CURL_DISABLE_FILE" != "1"; then
   SUPPORT_PROTOCOLS="$SUPPORT_PROTOCOLS FILE"
 fi
-if test "x$CURL_DISABLE_TELNET" != "x1"; then
+if test "$CURL_DISABLE_TELNET" != "1"; then
   SUPPORT_PROTOCOLS="$SUPPORT_PROTOCOLS TELNET"
 fi
-if test "x$CURL_DISABLE_LDAP" != "x1"; then
+if test "$CURL_DISABLE_LDAP" != "1"; then
   SUPPORT_PROTOCOLS="$SUPPORT_PROTOCOLS LDAP"
-  if test "x$CURL_DISABLE_LDAPS" != "x1"; then
-    if (test "x$USE_OPENLDAP" = "x1" && test "x$SSL_ENABLED" = "x1") ||
-      (test "x$USE_OPENLDAP" != "x1" && test "x$HAVE_LDAP_SSL" = "x1"); then
+  if test "$CURL_DISABLE_LDAPS" != "1"; then
+    if (test "$USE_OPENLDAP" = "1" && test "$SSL_ENABLED" = "1") ||
+       (test "$USE_OPENLDAP" != "1" && test "$HAVE_LDAP_SSL" = "1"); then
       SUPPORT_PROTOCOLS="$SUPPORT_PROTOCOLS LDAPS"
     fi
   fi
 fi
-if test "x$CURL_DISABLE_DICT" != "x1"; then
+if test "$CURL_DISABLE_DICT" != "1"; then
   SUPPORT_PROTOCOLS="$SUPPORT_PROTOCOLS DICT"
 fi
-if test "x$CURL_DISABLE_TFTP" != "x1"; then
+if test "$CURL_DISABLE_TFTP" != "1"; then
   SUPPORT_PROTOCOLS="$SUPPORT_PROTOCOLS TFTP"
 fi
-if test "x$CURL_DISABLE_GOPHER" != "x1"; then
+if test "$CURL_DISABLE_GOPHER" != "1"; then
   SUPPORT_PROTOCOLS="$SUPPORT_PROTOCOLS GOPHER"
-  if test "x$SSL_ENABLED" = "x1"; then
+  if test "$SSL_ENABLED" = "1"; then
     SUPPORT_PROTOCOLS="$SUPPORT_PROTOCOLS GOPHERS"
   fi
 fi
-if test "x$CURL_DISABLE_MQTT" != "x1"; then
+if test "$CURL_DISABLE_MQTT" != "1"; then
   SUPPORT_PROTOCOLS="$SUPPORT_PROTOCOLS MQTT"
 fi
-if test "x$CURL_DISABLE_POP3" != "x1"; then
+if test "$CURL_DISABLE_POP3" != "1"; then
   SUPPORT_PROTOCOLS="$SUPPORT_PROTOCOLS POP3"
-  if test "x$SSL_ENABLED" = "x1"; then
+  if test "$SSL_ENABLED" = "1"; then
     SUPPORT_PROTOCOLS="$SUPPORT_PROTOCOLS POP3S"
   fi
 fi
-if test "x$CURL_DISABLE_IMAP" != "x1"; then
+if test "$CURL_DISABLE_IMAP" != "1"; then
   SUPPORT_PROTOCOLS="$SUPPORT_PROTOCOLS IMAP"
-  if test "x$SSL_ENABLED" = "x1"; then
+  if test "$SSL_ENABLED" = "1"; then
     SUPPORT_PROTOCOLS="$SUPPORT_PROTOCOLS IMAPS"
   fi
 fi
-if test "x$CURL_DISABLE_SMB" != "x1" \
-    -a "x$use_curl_ntlm_core" = "xyes"; then
+if test "$CURL_DISABLE_SMB" != "1" && test "$use_curl_ntlm_core" = "yes"; then
   SUPPORT_PROTOCOLS="$SUPPORT_PROTOCOLS SMB"
-  if test "x$SSL_ENABLED" = "x1"; then
+  if test "$SSL_ENABLED" = "1"; then
     SUPPORT_PROTOCOLS="$SUPPORT_PROTOCOLS SMBS"
   fi
 fi
-if test "x$CURL_DISABLE_SMTP" != "x1"; then
+if test "$CURL_DISABLE_SMTP" != "1"; then
   SUPPORT_PROTOCOLS="$SUPPORT_PROTOCOLS SMTP"
-  if test "x$SSL_ENABLED" = "x1"; then
+  if test "$SSL_ENABLED" = "1"; then
     SUPPORT_PROTOCOLS="$SUPPORT_PROTOCOLS SMTPS"
   fi
 fi
-if test "x$USE_LIBSSH2" = "x1"; then
+if test "$USE_LIBSSH2" = "1"; then
   SUPPORT_PROTOCOLS="$SUPPORT_PROTOCOLS SCP"
   SUPPORT_PROTOCOLS="$SUPPORT_PROTOCOLS SFTP"
 fi
-if test "x$USE_LIBSSH" = "x1"; then
+if test "$USE_LIBSSH" = "1"; then
   SUPPORT_PROTOCOLS="$SUPPORT_PROTOCOLS SCP"
   SUPPORT_PROTOCOLS="$SUPPORT_PROTOCOLS SFTP"
 fi
-if test "x$CURL_DISABLE_IPFS" != "x1"; then
+if test "$CURL_DISABLE_IPFS" != "1"; then
   SUPPORT_PROTOCOLS="$SUPPORT_PROTOCOLS IPFS IPNS"
 fi
-if test "x$CURL_DISABLE_RTSP" != "x1"; then
+if test "$CURL_DISABLE_RTSP" != "1"; then
   SUPPORT_PROTOCOLS="$SUPPORT_PROTOCOLS RTSP"
 fi
-if test "x$USE_LIBRTMP" = "x1"; then
+if test "$USE_LIBRTMP" = "1"; then
   SUPPORT_PROTOCOLS="$SUPPORT_PROTOCOLS RTMP"
 fi
-if test "x$CURL_DISABLE_WEBSOCKETS" != "x1"; then
+if test "$CURL_DISABLE_WEBSOCKETS" != "1"; then
   SUPPORT_PROTOCOLS="$SUPPORT_PROTOCOLS WS"
-  if test "x$SSL_ENABLED" = "x1"; then
+  if test "$SSL_ENABLED" = "1"; then
     SUPPORT_PROTOCOLS="$SUPPORT_PROTOCOLS WSS"
   fi
 fi
@@ -5487,8 +5487,8 @@ XC_CHECK_BUILD_FLAGS
 SSL_BACKENDS=${ssl_backends}
 AC_SUBST(SSL_BACKENDS)
 
-if test "x$want_curldebug_assumed" = "xyes" &&
-  test "x$want_curldebug" = "xyes" && test "x$USE_ARES" = "x1"; then
+if test "$want_curldebug_assumed" = "yes" &&
+   test "$want_curldebug" = "yes" && test "$USE_ARES" = "1"; then
   ac_configure_args="$ac_configure_args --enable-curldebug"
 fi
 
diff --git a/curl-config.in b/curl-config.in
index ce23519c33..a1c8185875 100644
--- a/curl-config.in
+++ b/curl-config.in
@@ -149,7 +149,7 @@ while test "$#" -gt 0; do
     ;;
 
   --libs)
-    if test "@libdir@" != '/usr/lib' -a "@libdir@" != '/usr/lib64'; then
+    if test "@libdir@" != '/usr/lib' && test "@libdir@" != '/usr/lib64'; then
       curllibdir="-L@libdir@ "
     else
       curllibdir=''
diff --git a/docs/libcurl/libcurl.m4 b/docs/libcurl/libcurl.m4
index 973493f03a..96248ddc25 100644
--- a/docs/libcurl/libcurl.m4
+++ b/docs/libcurl/libcurl.m4
@@ -86,7 +86,7 @@ AC_DEFUN([LIBCURL_CHECK_CONFIG],
     AS_HELP_STRING([--with-libcurl=PREFIX],[look for the curl library in PREFIX/lib and headers in PREFIX/include]),
     [_libcurl_with=$withval],[_libcurl_with=ifelse([$1],,[yes],[$1])])
 
-  if test "$_libcurl_with" != "no"; then
+  if test "x$_libcurl_with" != "xno"; then
 
     AC_PROG_AWK
 
@@ -102,7 +102,7 @@ AC_DEFUN([LIBCURL_CHECK_CONFIG],
       AC_PATH_PROG([_libcurl_config],[curl-config],[],[$PATH])
     fi
 
-    if test x$_libcurl_config != "x"; then
+    if test -n "$_libcurl_config"; then
       AC_CACHE_CHECK([for the version of libcurl],
         [libcurl_cv_lib_curl_version],
         [libcurl_cv_lib_curl_version=`$_libcurl_config --version | $AWK '{print $[]2}'`])
@@ -110,11 +110,11 @@ AC_DEFUN([LIBCURL_CHECK_CONFIG],
       _libcurl_version=`echo $libcurl_cv_lib_curl_version | $_libcurl_version_parse`
       _libcurl_wanted=`echo ifelse([$2],,[0],[$2]) | $_libcurl_version_parse`
 
-      if test $_libcurl_wanted -gt 0; then
+      if test "$_libcurl_wanted" -gt 0; then
         AC_CACHE_CHECK([for libcurl >= version $2],
           [libcurl_cv_lib_version_ok],
           [
-          if test $_libcurl_version -ge $_libcurl_wanted; then
+          if test "$_libcurl_version" -ge "$_libcurl_wanted"; then
             libcurl_cv_lib_version_ok=yes
           else
             libcurl_cv_lib_version_ok=no
@@ -122,11 +122,11 @@ AC_DEFUN([LIBCURL_CHECK_CONFIG],
           ])
       fi
 
-      if test $_libcurl_wanted -eq 0 || test x$libcurl_cv_lib_version_ok = xyes; then
-        if test x"$LIBCURL_CPPFLAGS" = "x"; then
+      if test "$_libcurl_wanted" -eq 0 || test "$libcurl_cv_lib_version_ok" = "yes"; then
+        if test -z "$LIBCURL_CPPFLAGS"; then
           LIBCURL_CPPFLAGS=`$_libcurl_config --cflags`
         fi
-        if test x"$LIBCURL" = "x"; then
+        if test -z "$LIBCURL"; then
           LIBCURL=`$_libcurl_config --libs`
 
           # This is so silly, but Apple actually has a bug in their
@@ -143,7 +143,7 @@ AC_DEFUN([LIBCURL_CHECK_CONFIG],
         _libcurl_features=`$_libcurl_config --feature`
 
         # Is it modern enough to have --protocols? (7.12.4)
-        if test $_libcurl_version -ge 461828; then
+        if test "$_libcurl_version" -ge 461828; then
           _libcurl_protocols=`$_libcurl_config --protocols`
         fi
       else
@@ -153,7 +153,7 @@ AC_DEFUN([LIBCURL_CHECK_CONFIG],
       unset _libcurl_wanted
     fi
 
-    if test $_libcurl_try_link = yes; then
+    if test "$_libcurl_try_link" = "yes"; then
 
       # we did not find curl-config, so let's see if the user-supplied
       # link line (or failing that, "-lcurl") is enough.
@@ -187,7 +187,7 @@ AC_DEFUN([LIBCURL_CHECK_CONFIG],
         unset _libcurl_save_libs
         ])
 
-      if test $libcurl_cv_lib_curl_usable = yes; then
+      if test "$libcurl_cv_lib_curl_usable" = "yes"; then
 
         # Does curl_free() exist in this version of libcurl?
         # If not, fake it with free()
@@ -217,25 +217,25 @@ AC_DEFUN([LIBCURL_CHECK_CONFIG],
           eval AS_TR_SH(libcurl_feature_$_libcurl_feature)=yes
         done
 
-        if test "x$_libcurl_protocols" = "x"; then
+        if test -z "$_libcurl_protocols"; then
 
           # We do not have --protocols, so just assume that all
           # protocols are available
           _libcurl_protocols="HTTP FTP FILE TELNET LDAP DICT TFTP"
 
-          if test x$libcurl_feature_SSL = xyes; then
+          if test "$libcurl_feature_SSL" = "yes"; then
             _libcurl_protocols="$_libcurl_protocols HTTPS"
 
             # FTPS was not standards-compliant until version
             # 7.11.0 (0x070b00 == 461568)
-            if test $_libcurl_version -ge 461568; then
+            if test "$_libcurl_version" -ge 461568; then
               _libcurl_protocols="$_libcurl_protocols FTPS"
             fi
           fi
 
           # RTSP, IMAP, POP3 and SMTP were added in
           # 7.20.0 (0x071400 == 463872)
-          if test $_libcurl_version -ge 463872; then
+          if test "$_libcurl_version" -ge 463872; then
             _libcurl_protocols="$_libcurl_protocols RTSP IMAP POP3 SMTP"
           fi
         fi
@@ -261,7 +261,7 @@ AC_DEFUN([LIBCURL_CHECK_CONFIG],
     unset _libcurl_ldflags
   fi
 
-  if test x$_libcurl_with = xno || test x$libcurl_cv_lib_curl_usable != xyes; then
+  if test "x$_libcurl_with" = "xno" || test "$libcurl_cv_lib_curl_usable" != "yes"; then
     # This is the IF-NO path
     ifelse([$4],,:,[$4])
   else
diff --git a/m4/curl-amissl.m4 b/m4/curl-amissl.m4
index a70a536632..86468890e8 100644
--- a/m4/curl-amissl.m4
+++ b/m4/curl-amissl.m4
@@ -25,7 +25,7 @@
 AC_DEFUN([CURL_WITH_AMISSL], [
 AC_MSG_CHECKING([whether to enable Amiga native SSL/TLS (AmiSSL v5)])
 if test "$HAVE_PROTO_BSDSOCKET_H" = "1"; then
-  if test "x$OPT_AMISSL" != xno; then
+  if test "x$OPT_AMISSL" != "xno"; then
     ssl_msg=
     AC_COMPILE_IFELSE([
       AC_LANG_PROGRAM([[
@@ -43,7 +43,7 @@ if test "$HAVE_PROTO_BSDSOCKET_H" = "1"; then
     ],[
       AC_MSG_RESULT([yes])
       ssl_msg="AmiSSL"
-      test amissl != "$DEFAULT_SSL_BACKEND" || VALID_DEFAULT_SSL_BACKEND=yes
+      test "amissl" != "$DEFAULT_SSL_BACKEND" || VALID_DEFAULT_SSL_BACKEND=yes
       AMISSL_ENABLED=1
       OPENSSL_ENABLED=1
       # Use AmiSSL's built-in ca bundle
diff --git a/m4/curl-apple-sectrust.m4 b/m4/curl-apple-sectrust.m4
index d42fe860a5..c70b7ac8cd 100644
--- a/m4/curl-apple-sectrust.m4
+++ b/m4/curl-apple-sectrust.m4
@@ -24,7 +24,7 @@
 
 AC_DEFUN([CURL_WITH_APPLE_SECTRUST], [
 AC_MSG_CHECKING([whether to enable Apple OS native certificate validation])
-if test "x$OPT_APPLE_SECTRUST" = xyes; then
+if test "x$OPT_APPLE_SECTRUST" = "xyes"; then
   AC_COMPILE_IFELSE([
     AC_LANG_PROGRAM([[
       #include <sys/types.h>
@@ -41,10 +41,10 @@ if test "x$OPT_APPLE_SECTRUST" = xyes; then
   ],[
     build_for_apple="no"
   ])
-  if test "x$build_for_apple" = "xno"; then
+  if test "$build_for_apple" = "no"; then
     AC_MSG_ERROR([Apple SecTrust can only be enabled for Apple OS targets])
   fi
-  if test "x$OPENSSL_ENABLED" = "x1" -o "x$GNUTLS_ENABLED" = "x1"; then
+  if test "$OPENSSL_ENABLED" = "1" || test "$GNUTLS_ENABLED" = "1"; then
     AC_MSG_RESULT(yes)
     AC_DEFINE(USE_APPLE_SECTRUST, 1, [enable Apple OS certificate validation])
     APPLE_SECTRUST_ENABLED=1
diff --git a/m4/curl-compilers.m4 b/m4/curl-compilers.m4
index 343391d602..7b4b5bed23 100644
--- a/m4/curl-compilers.m4
+++ b/m4/curl-compilers.m4
@@ -88,7 +88,7 @@ AC_DEFUN([CURL_CHECK_COMPILER_CLANG], [
     AC_MSG_RESULT([yes])
     AC_MSG_CHECKING([if compiler is xlclang])
     CURL_CHECK_DEF([__ibmxl__], [], [silent])
-    if test "$curl_cv_have_def___ibmxl__" = "yes" ; then
+    if test "$curl_cv_have_def___ibmxl__" = "yes"; then
       dnl IBM's almost-compatible clang version
       AC_MSG_RESULT([yes])
       compiler_id="XLCLANG"
@@ -118,7 +118,7 @@ AC_DEFUN([CURL_CHECK_COMPILER_CLANG], [
     clangvlo=`echo $clangver | cut -d . -f2`
     compiler_ver="$clangver"
     compiler_num=`(expr $clangvhi "*" 100 + $clangvlo) 2>/dev/null`
-    if test "$appleclang" = '1' && test "$oldapple" = '0'; then
+    if test "$appleclang" = "1" && test "$oldapple" = "0"; then
       dnl Starting with Xcode 7 / clang 3.7, Apple clang does not tell its upstream version
       if   test "$compiler_num" -ge '1700'; then compiler_num='1901'
       elif test "$compiler_num" -ge '1600'; then compiler_num='1700'
@@ -396,7 +396,8 @@ AC_DEFUN([CURL_CONVERT_INCLUDE_TO_ISYSTEM], [
   AC_REQUIRE([CURL_CHECK_COMPILER])dnl
   AC_MSG_CHECKING([convert -I options to -isystem])
   if test "$compiler_id" = "GNU_C" ||
-    test "$compiler_id" = "CLANG" -o "$compiler_id" = "APPLECLANG"; then
+     test "$compiler_id" = "CLANG" ||
+     test "$compiler_id" = "APPLECLANG"; then
     AC_MSG_RESULT([yes])
     tmp_has_include="no"
     tmp_chg_FLAGS="$CFLAGS"
@@ -475,7 +476,7 @@ AC_DEFUN([CURL_COMPILER_WORKS_IFELSE], [
     ])
   fi
   dnl only do runtime verification when not cross-compiling
-  if test "x$cross_compiling" != "xyes" &&
+  if test "$cross_compiling" != "yes" &&
     test "$tmp_compiler_works" = "yes"; then
     CURL_RUN_IFELSE([
       AC_LANG_PROGRAM([[
@@ -632,7 +633,7 @@ AC_DEFUN([CURL_SET_COMPILER_BASIC_OPTS], [
     squeeze tmp_CPPFLAGS
     squeeze tmp_CFLAGS
     #
-    if test ! -z "$tmp_CFLAGS" || test ! -z "$tmp_CPPFLAGS"; then
+    if test -n "$tmp_CFLAGS" || test -n "$tmp_CPPFLAGS"; then
       AC_MSG_CHECKING([if compiler accepts some basic options])
       CPPFLAGS="$tmp_save_CPPFLAGS $tmp_CPPFLAGS"
       CFLAGS="$tmp_save_CFLAGS $tmp_CFLAGS"
@@ -972,7 +973,7 @@ AC_DEFUN([CURL_SET_COMPILER_WARNING_OPTS], [
           #
           dnl Do not enable -pedantic when cross-compiling with a gcc older
           dnl than 3.0, to avoid warnings from third party system headers.
-          if test "x$cross_compiling" != "xyes" ||
+          if test "$cross_compiling" != "yes" ||
             test "$compiler_num" -ge "300"; then
             tmp_CFLAGS="$tmp_CFLAGS -pedantic"
           fi
@@ -985,7 +986,7 @@ AC_DEFUN([CURL_SET_COMPILER_WARNING_OPTS], [
           if test "$compiler_num" -ge "104"; then
             CURL_ADD_COMPILER_WARNINGS([tmp_CFLAGS], [pointer-arith write-strings])
             dnl If not cross-compiling with a gcc older than 3.0
-            if test "x$cross_compiling" != "xyes" ||
+            if test "$cross_compiling" != "yes" ||
               test "$compiler_num" -ge "300"; then
               CURL_ADD_COMPILER_WARNINGS([tmp_CFLAGS], [unused shadow])
             fi
@@ -995,7 +996,7 @@ AC_DEFUN([CURL_SET_COMPILER_WARNING_OPTS], [
           if test "$compiler_num" -ge "207"; then
             CURL_ADD_COMPILER_WARNINGS([tmp_CFLAGS], [nested-externs])
             dnl If not cross-compiling with a gcc older than 3.0
-            if test "x$cross_compiling" != "xyes" ||
+            if test "$cross_compiling" != "yes" ||
               test "$compiler_num" -ge "300"; then
               CURL_ADD_COMPILER_WARNINGS([tmp_CFLAGS], [missing-declarations])
               CURL_ADD_COMPILER_WARNINGS([tmp_CFLAGS], [missing-prototypes])
@@ -1173,7 +1174,7 @@ AC_DEFUN([CURL_SET_COMPILER_WARNING_OPTS], [
         else
           dnl When cross-compiling with a gcc older than 3.0, disable
           dnl some warnings triggered on third party system headers.
-          if test "x$cross_compiling" = "xyes"; then
+          if test "$cross_compiling" = "yes"; then
             if test "$compiler_num" -ge "104"; then
               dnl gcc 1.4 or later
               tmp_CFLAGS="$tmp_CFLAGS -Wno-unused -Wno-shadow"
@@ -1190,19 +1191,19 @@ AC_DEFUN([CURL_SET_COMPILER_WARNING_OPTS], [
           tmp_CFLAGS="$tmp_CFLAGS -Wno-shadow"
           tmp_CFLAGS="$tmp_CFLAGS -Wno-unreachable-code"
         fi
-        if test "$compiler_num" -ge "402" -a "$compiler_num" -lt "406"; then
+        if test "$compiler_num" -ge "402" && test "$compiler_num" -lt "406"; then
           dnl GCC <4.6 do not support #pragma to suppress warnings locally. Disable globally instead.
           tmp_CFLAGS="$tmp_CFLAGS -Wno-overlength-strings"
         fi
-        if test "$compiler_num" -ge "400" -a "$compiler_num" -lt "407"; then
+        if test "$compiler_num" -ge "400" && test "$compiler_num" -lt "407"; then
           dnl https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84685
           tmp_CFLAGS="$tmp_CFLAGS -Wno-missing-field-initializers"
         fi
-        if test "$compiler_num" -ge "403" -a "$compiler_num" -lt "408"; then
+        if test "$compiler_num" -ge "403" && test "$compiler_num" -lt "408"; then
           dnl Avoid false positives
           tmp_CFLAGS="$tmp_CFLAGS -Wno-type-limits"
         fi
-        if test "$compiler_num" -ge "501" -a "$compiler_num" -lt "505"; then
+        if test "$compiler_num" -ge "501" && test "$compiler_num" -lt "505"; then
           dnl Avoid false positives
           tmp_CFLAGS="$tmp_CFLAGS -Wno-conversion"
         fi
@@ -1308,7 +1309,7 @@ AC_DEFUN([CURL_SET_COMPILER_WARNING_OPTS], [
     squeeze tmp_CPPFLAGS
     squeeze tmp_CFLAGS
     #
-    if test ! -z "$tmp_CFLAGS" || test ! -z "$tmp_CPPFLAGS"; then
+    if test -n "$tmp_CFLAGS" || test -n "$tmp_CPPFLAGS"; then
       AC_MSG_CHECKING([if compiler accepts strict warning options])
       CPPFLAGS="$tmp_save_CPPFLAGS $tmp_CPPFLAGS"
       CFLAGS="$tmp_save_CFLAGS $tmp_CFLAGS"
@@ -1491,7 +1492,7 @@ AC_DEFUN([CURL_CHECK_COMPILER_SYMBOL_HIDING], [
     GNU_C)
       dnl Only gcc 3.4 or later
       if test "$compiler_num" -ge "304"; then
-        if $CC --help --verbose 2>/dev/null | grep fvisibility= >/dev/null ; then
+        if $CC --help --verbose 2>/dev/null | grep fvisibility= >/dev/null; then
           tmp_EXTERN="__attribute__((__visibility__(\"default\")))"
           tmp_CFLAGS="-fvisibility=hidden"
           supports_symbol_hiding="yes"
@@ -1501,7 +1502,7 @@ AC_DEFUN([CURL_CHECK_COMPILER_SYMBOL_HIDING], [
     INTEL_UNIX_C)
       dnl Only icc 9.0 or later
       if test "$compiler_num" -ge "900"; then
-        if $CC --help --verbose 2>&1 | grep fvisibility= > /dev/null ; then
+        if $CC --help --verbose 2>&1 | grep fvisibility= > /dev/null; then
           tmp_save_CFLAGS="$CFLAGS"
           CFLAGS="$CFLAGS -fvisibility=hidden"
           AC_LINK_IFELSE([
@@ -1520,7 +1521,7 @@ AC_DEFUN([CURL_CHECK_COMPILER_SYMBOL_HIDING], [
       fi
       ;;
     SUNPRO_C)
-      if $CC 2>&1 | grep flags >/dev/null && $CC -flags | grep xldscope= >/dev/null ; then
+      if $CC 2>&1 | grep flags >/dev/null && $CC -flags | grep xldscope= >/dev/null; then
         tmp_EXTERN="__global"
         tmp_CFLAGS="-xldscope=hidden"
         supports_symbol_hiding="yes"
diff --git a/m4/curl-confopts.m4 b/m4/curl-confopts.m4
index 5149e8a34a..a540373692 100644
--- a/m4/curl-confopts.m4
+++ b/m4/curl-confopts.m4
@@ -93,7 +93,7 @@ AS_HELP_STRING([--disable-ares],[Disable c-ares for DNS lookups]),
     *)
       dnl --enable-ares option used
       want_ares="yes"
-      if test -n "$enableval" && test "$enableval" != "yes"; then
+      if test -n "$enableval" && test "x$enableval" != "xyes"; then
         want_ares_path="$enableval"
       fi
       ;;
@@ -392,15 +392,15 @@ AC_DEFUN([CURL_CHECK_NONBLOCKING_SOCKET], [
   tst_method="unknown"
 
   AC_MSG_CHECKING([how to set a socket into non-blocking mode])
-  if test "x$curl_cv_func_fcntl_o_nonblock" = "xyes"; then
+  if test "$curl_cv_func_fcntl_o_nonblock" = "yes"; then
     tst_method="fcntl O_NONBLOCK"
-  elif test "x$curl_cv_func_ioctl_fionbio" = "xyes"; then
+  elif test "$curl_cv_func_ioctl_fionbio" = "yes"; then
     tst_method="ioctl FIONBIO"
-  elif test "x$curl_cv_func_ioctlsocket_fionbio" = "xyes"; then
+  elif test "$curl_cv_func_ioctlsocket_fionbio" = "yes"; then
     tst_method="ioctlsocket FIONBIO"
-  elif test "x$curl_cv_func_ioctlsocket_camel_fionbio" = "xyes"; then
+  elif test "$curl_cv_func_ioctlsocket_camel_fionbio" = "yes"; then
     tst_method="IoctlSocket FIONBIO"
-  elif test "x$curl_cv_func_setsockopt_so_nonblock" = "xyes"; then
+  elif test "$curl_cv_func_setsockopt_so_nonblock" = "yes"; then
     tst_method="setsockopt SO_NONBLOCK"
   fi
   AC_MSG_RESULT([$tst_method])
@@ -433,7 +433,7 @@ AC_DEFUN([CURL_CONFIGURE_SYMBOL_HIDING], [
   else
     AC_MSG_RESULT([no])
   fi
-  AM_CONDITIONAL(DOING_CURL_SYMBOL_HIDING, test x$doing_symbol_hiding = xyes)
+  AM_CONDITIONAL(DOING_CURL_SYMBOL_HIDING, test "$doing_symbol_hiding" = "yes")
   AC_SUBST(CFLAG_CURL_SYMBOL_HIDING)
 ])
 
@@ -456,7 +456,7 @@ AC_DEFUN([CURL_CHECK_LIB_ARES], [
       dnl c-ares library path has been specified
       ARES_PCDIR="$want_ares_path/lib/pkgconfig"
       CURL_CHECK_PKGCONFIG(libcares, [$ARES_PCDIR])
-      if test "$PKGCONFIG" != "no" ; then
+      if test "$PKGCONFIG" != "no"; then
         ares_LIBS=`CURL_EXPORT_PCDIR([$ARES_PCDIR])
           $PKGCONFIG --libs-only-l libcares`
         ares_LDFLAGS=`CURL_EXPORT_PCDIR([$ARES_PCDIR])
@@ -475,7 +475,7 @@ AC_DEFUN([CURL_CHECK_LIB_ARES], [
     else
       dnl c-ares path not specified, use defaults
       CURL_CHECK_PKGCONFIG(libcares)
-      if test "$PKGCONFIG" != "no" ; then
+      if test "$PKGCONFIG" != "no"; then
         ares_LIBS=`$PKGCONFIG --libs-only-l libcares`
         ares_LDFLAGS=`$PKGCONFIG --libs-only-L libcares`
         ares_CPPFLAGS=`$PKGCONFIG --cflags-only-I libcares`
diff --git a/m4/curl-functions.m4 b/m4/curl-functions.m4
index a9b9ee5844..5512a5d28c 100644
--- a/m4/curl-functions.m4
+++ b/m4/curl-functions.m4
@@ -1339,7 +1339,7 @@ AC_DEFUN([CURL_CHECK_FUNC_GETADDRINFO], [
   fi
   #
   dnl only do runtime verification when not cross-compiling
-  if test "x$cross_compiling" != "xyes" &&
+  if test "$cross_compiling" != "yes" &&
     test "$tst_compi_getaddrinfo" = "yes"; then
     AC_MSG_CHECKING([if getaddrinfo seems to work])
     CURL_RUN_IFELSE([
@@ -1415,7 +1415,7 @@ AC_DEFUN([CURL_CHECK_FUNC_GETADDRINFO], [
   #
   if test "$curl_cv_func_getaddrinfo" = "yes"; then
     AC_MSG_CHECKING([if getaddrinfo is threadsafe])
-    if test "$curl_cv_apple" = 'yes'; then
+    if test "$curl_cv_apple" = "yes"; then
       dnl Darwin 6.0 and macOS 10.2.X and newer
       tst_tsafe_getaddrinfo="yes"
     fi
@@ -2027,7 +2027,7 @@ AC_DEFUN([CURL_CHECK_FUNC_GETIFADDRS], [
   fi
   #
   dnl only do runtime verification when not cross-compiling
-  if test "x$cross_compiling" != "xyes" &&
+  if test "$cross_compiling" != "yes" &&
     test "$tst_compi_getifaddrs" = "yes"; then
     AC_MSG_CHECKING([if getifaddrs seems to work])
     CURL_RUN_IFELSE([
@@ -2148,7 +2148,7 @@ AC_DEFUN([CURL_CHECK_FUNC_GMTIME_R], [
   fi
   #
   dnl only do runtime verification when not cross-compiling
-  if test "x$cross_compiling" != "xyes" &&
+  if test "$cross_compiling" != "yes" &&
     test "$tst_compi_gmtime_r" = "yes"; then
     AC_MSG_CHECKING([if gmtime_r seems to work])
     CURL_RUN_IFELSE([
@@ -2268,7 +2268,7 @@ AC_DEFUN([CURL_CHECK_FUNC_INET_NTOP], [
   fi
   #
   dnl only do runtime verification when not cross-compiling
-  if test "x$cross_compiling" != "xyes" &&
+  if test "$cross_compiling" != "yes" &&
     test "$tst_compi_inet_ntop" = "yes"; then
     AC_MSG_CHECKING([if inet_ntop seems to work])
     CURL_RUN_IFELSE([
@@ -2429,7 +2429,7 @@ AC_DEFUN([CURL_CHECK_FUNC_INET_PTON], [
   fi
   #
   dnl only do runtime verification when not cross-compiling
-  if test "x$cross_compiling" != "xyes" &&
+  if test "$cross_compiling" != "yes" &&
     test "$tst_compi_inet_pton" = "yes"; then
     AC_MSG_CHECKING([if inet_pton seems to work])
     CURL_RUN_IFELSE([
@@ -4016,7 +4016,7 @@ AC_DEFUN([CURL_CHECK_FUNC_STRERROR_R], [
   fi
   #
   dnl only do runtime verification when not cross-compiling
-  if test "x$cross_compiling" != "xyes" &&
+  if test "$cross_compiling" != "yes" &&
     test "$tst_glibc_strerror_r" = "yes"; then
     AC_MSG_CHECKING([if strerror_r seems to work])
     CURL_RUN_IFELSE([
@@ -4079,7 +4079,7 @@ AC_DEFUN([CURL_CHECK_FUNC_STRERROR_R], [
   fi
   #
   dnl only do runtime verification when not cross-compiling
-  if test "x$cross_compiling" != "xyes" &&
+  if test "$cross_compiling" != "yes" &&
     test "$tst_posix_strerror_r" = "yes"; then
     AC_MSG_CHECKING([if strerror_r seems to work])
     CURL_RUN_IFELSE([
@@ -4259,7 +4259,7 @@ dnl CURL_LIBRARY_PATH variable. It keeps the LD_LIBRARY_PATH
 dnl changes contained within this macro.
 
 AC_DEFUN([CURL_RUN_IFELSE], [
-  if test "$curl_cv_apple" = 'yes'; then
+  if test "$curl_cv_apple" = "yes"; then
     AC_RUN_IFELSE([AC_LANG_SOURCE([$1])], $2, $3, $4)
   else
     oldcc=$CC
@@ -4291,7 +4291,7 @@ AC_DEFUN([CURL_COVERAGE],[
     coverage="$enableval")
 
   dnl if not gcc or clang switch off again
-  AS_IF([test "$compiler_id" != "GNU_C" -a "$compiler_id" != "CLANG" -a "$compiler_id" != "APPLECLANG"], coverage="no" )
+  AS_IF([test "$compiler_id" != "GNU_C" && test "$compiler_id" != "CLANG" && test "$compiler_id" != "APPLECLANG"], coverage="no" )
   AC_MSG_RESULT($coverage)
 
   if test "x$coverage" = "xyes"; then
@@ -4390,11 +4390,11 @@ AC_DEFUN([CURL_SIZEOF], [
       r=0
     ])
     dnl get out of the loop once matched
-    if test $r -gt 0; then
+    if test "$r" -gt 0; then
       break;
     fi
   done
-  if test $r -eq 0; then
+  if test "$r" -eq 0; then
     AC_MSG_ERROR([Failed to find size of $1])
   fi
   AC_MSG_RESULT($r)
diff --git a/m4/curl-gnutls.m4 b/m4/curl-gnutls.m4
index f1aa04d3fa..533d72129e 100644
--- a/m4/curl-gnutls.m4
+++ b/m4/curl-gnutls.m4
@@ -27,10 +27,10 @@ dnl check for GnuTLS
 dnl ----------------------------------------------------
 
 AC_DEFUN([CURL_WITH_GNUTLS], [
-if test "x$OPT_GNUTLS" != xno; then
+if test "x$OPT_GNUTLS" != "xno"; then
   ssl_msg=
 
-  if test X"$OPT_GNUTLS" != Xno; then
+  if test "x$OPT_GNUTLS" != "xno"; then
 
     addld=""
     addlib=""
@@ -42,7 +42,7 @@ if test "x$OPT_GNUTLS" != xno; then
       dnl this is with no particular path given
       CURL_CHECK_PKGCONFIG(gnutls)
 
-      if test "$PKGCONFIG" != "no" ; then
+      if test "$PKGCONFIG" != "no"; then
         addlib=`$PKGCONFIG --libs-only-l gnutls`
         addld=`$PKGCONFIG --libs-only-L gnutls`
         addcflags=`$PKGCONFIG --cflags-only-I gnutls`
@@ -106,7 +106,7 @@ if test "x$OPT_GNUTLS" != xno; then
         USE_GNUTLS="yes"
         ssl_msg="GnuTLS"
         QUIC_ENABLED=yes
-        test gnutls != "$DEFAULT_SSL_BACKEND" || VALID_DEFAULT_SSL_BACKEND=yes
+        test "gnutls" != "$DEFAULT_SSL_BACKEND" || VALID_DEFAULT_SSL_BACKEND=yes
       ],
       [
         LIBS="$CLEANLIBS"
@@ -115,7 +115,7 @@ if test "x$OPT_GNUTLS" != xno; then
         LDFLAGSPC="$CLEANLDFLAGSPC"
       ])
 
-      if test "x$USE_GNUTLS" = "xyes"; then
+      if test "$USE_GNUTLS" = "yes"; then
         AC_MSG_NOTICE([detected GnuTLS version $version])
         check_for_ca_bundle=1
         if test -n "$gtlslib"; then
@@ -123,7 +123,7 @@ if test "x$OPT_GNUTLS" != xno; then
           dnl linker does not search through, we need to add it to
           dnl CURL_LIBRARY_PATH to prevent further configure tests to fail
           dnl due to this
-          if test "x$cross_compiling" != "xyes"; then
+          if test "$cross_compiling" != "yes"; then
             CURL_LIBRARY_PATH="$CURL_LIBRARY_PATH:$gtlslib"
             export CURL_LIBRARY_PATH
             AC_MSG_NOTICE([Added $gtlslib to CURL_LIBRARY_PATH])
@@ -147,12 +147,12 @@ if test "$GNUTLS_ENABLED" = "1"; then
   AC_CHECK_LIB(gnutls, nettle_MD5Init, [ USE_GNUTLS_NETTLE=1 ])
 
   # If not, try linking directly to both of them to see if they are available
-  if test "$USE_GNUTLS_NETTLE" = ""; then
+  if test -z "$USE_GNUTLS_NETTLE"; then
 
     dnl this is with no particular path given
     CURL_CHECK_PKGCONFIG(nettle)
 
-    if test "$PKGCONFIG" != "no" ; then
+    if test "$PKGCONFIG" != "no"; then
       addlib=`$PKGCONFIG --libs-only-l nettle`
       addld=`$PKGCONFIG --libs-only-L nettle`
       addcflags=`$PKGCONFIG --cflags-only-I nettle`
@@ -192,7 +192,7 @@ if test "$GNUTLS_ENABLED" = "1"; then
         fi
       fi
     fi
-    if test "$USE_GNUTLS_NETTLE" = ""; then
+    if test -z "$USE_GNUTLS_NETTLE"; then
       AC_MSG_ERROR([GnuTLS found, but nettle was not found])
     fi
   else
diff --git a/m4/curl-mbedtls.m4 b/m4/curl-mbedtls.m4
index 93da5b25e0..7c5bccd229 100644
--- a/m4/curl-mbedtls.m4
+++ b/m4/curl-mbedtls.m4
@@ -27,19 +27,19 @@ dnl check for mbedTLS
 dnl ----------------------------------------------------
 AC_DEFUN([CURL_WITH_MBEDTLS], [
 
-if test "x$OPT_MBEDTLS" != xno; then
+if test "x$OPT_MBEDTLS" != "xno"; then
   _cppflags=$CPPFLAGS
   _ldflags=$LDFLAGS
   _ldflagspc=$LDFLAGSPC
   ssl_msg=
 
-  if test X"$OPT_MBEDTLS" != Xno; then
+  if test "x$OPT_MBEDTLS" != "xno"; then
 
-    if test "$OPT_MBEDTLS" = "yes"; then
+    if test "x$OPT_MBEDTLS" = "xyes"; then
       OPT_MBEDTLS=""
     fi
 
-    if test -z "$OPT_MBEDTLS" ; then
+    if test -z "$OPT_MBEDTLS"; then
       dnl check for lib first without setting any new path
 
       AC_CHECK_LIB(mbedtls, mbedtls_havege_init,
@@ -49,7 +49,7 @@ if test "x$OPT_MBEDTLS" != xno; then
         MBEDTLS_ENABLED=1
         USE_MBEDTLS="yes"
         ssl_msg="mbedTLS"
-        test mbedtls != "$DEFAULT_SSL_BACKEND" || VALID_DEFAULT_SSL_BACKEND=yes
+        test "mbedtls" != "$DEFAULT_SSL_BACKEND" || VALID_DEFAULT_SSL_BACKEND=yes
       ], [], -lmbedx509 -lmbedcrypto)
     fi
 
@@ -58,7 +58,7 @@ if test "x$OPT_MBEDTLS" != xno; then
     addcflags=""
     mbedtlslib=""
 
-    if test "x$USE_MBEDTLS" != "xyes"; then
+    if test "$USE_MBEDTLS" != "yes"; then
       dnl add the path and test again
       addld=-L$OPT_MBEDTLS/lib$libsuff
       addcflags=-I$OPT_MBEDTLS/include
@@ -76,7 +76,7 @@ if test "x$OPT_MBEDTLS" != xno; then
         MBEDTLS_ENABLED=1
         USE_MBEDTLS="yes"
         ssl_msg="mbedTLS"
-        test mbedtls != "$DEFAULT_SSL_BACKEND" || VALID_DEFAULT_SSL_BACKEND=yes
+        test "mbedtls" != "$DEFAULT_SSL_BACKEND" || VALID_DEFAULT_SSL_BACKEND=yes
         ],
         [
           CPPFLAGS=$_cppflags
@@ -85,7 +85,7 @@ if test "x$OPT_MBEDTLS" != xno; then
         ], -lmbedx509 -lmbedcrypto)
     fi
 
-    if test "x$USE_MBEDTLS" = "xyes"; then
+    if test "$USE_MBEDTLS" = "yes"; then
       AC_MSG_NOTICE([detected mbedTLS])
       check_for_ca_bundle=1
 
@@ -96,7 +96,7 @@ if test "x$OPT_MBEDTLS" != xno; then
         dnl linker does not search through, we need to add it to
         dnl CURL_LIBRARY_PATH to prevent further configure tests to fail
         dnl due to this
-        if test "x$cross_compiling" != "xyes"; then
+        if test "$cross_compiling" != "yes"; then
           CURL_LIBRARY_PATH="$CURL_LIBRARY_PATH:$mbedtlslib"
           export CURL_LIBRARY_PATH
           AC_MSG_NOTICE([Added $mbedtlslib to CURL_LIBRARY_PATH])
diff --git a/m4/curl-openssl.m4 b/m4/curl-openssl.m4
index b9b93e2ea0..3892e0e89f 100644
--- a/m4/curl-openssl.m4
+++ b/m4/curl-openssl.m4
@@ -30,7 +30,7 @@ dnl Check for OpenSSL libraries and headers
 dnl **********************************************************************
 
 AC_DEFUN([CURL_WITH_OPENSSL], [
-if test "x$OPT_OPENSSL" != xno; then
+if test "x$OPT_OPENSSL" != "xno"; then
   ssl_msg=
 
   dnl backup the pre-ssl variables
@@ -102,7 +102,7 @@ if test "x$OPT_OPENSSL" != xno; then
       dnl in case pkg-config comes up empty, use what we got
       dnl via --with-openssl
       LIB_OPENSSL="$PREFIX_OPENSSL/lib$libsuff"
-      if test "$PREFIX_OPENSSL" != "/usr" ; then
+      if test "$PREFIX_OPENSSL" != "/usr"; then
         SSL_LDFLAGS="-L$LIB_OPENSSL"
         SSL_CPPFLAGS="-I$PREFIX_OPENSSL/include"
       fi
@@ -113,7 +113,7 @@ if test "x$OPT_OPENSSL" != xno; then
 
     CURL_CHECK_PKGCONFIG(openssl, [$OPENSSL_PCDIR])
 
-    if test "$PKGCONFIG" != "no" ; then
+    if test "$PKGCONFIG" != "no"; then
       SSL_LIBS=`CURL_EXPORT_PCDIR([$OPENSSL_PCDIR]) dnl
         $PKGCONFIG --libs-only-l --libs-only-other openssl 2>/dev/null`
 
@@ -148,11 +148,11 @@ if test "x$OPT_OPENSSL" != xno; then
     HAVECRYPTO="yes"
     LIBS="-lcrypto $LIBS"
     ],[
-    if test -n "$LIB_OPENSSL" ; then
+    if test -n "$LIB_OPENSSL"; then
       LDFLAGS="$CLEANLDFLAGS -L$LIB_OPENSSL"
       LDFLAGSPC="$CLEANLDFLAGSPC -L$LIB_OPENSSL"
     fi
-    if test "$PKGCONFIG" = "no" -a -n "$PREFIX_OPENSSL" ; then
+    if test "$PKGCONFIG" = "no" && test -n "$PREFIX_OPENSSL"; then
       # only set this if pkg-config was not used
       CPPFLAGS="$CLEANCPPFLAGS -I$PREFIX_OPENSSL/include"
     fi
@@ -203,33 +203,33 @@ if test "x$OPT_OPENSSL" != xno; then
     ])
   ])
 
-  if test X"$HAVECRYPTO" = X"yes"; then
+  if test "$HAVECRYPTO" = "yes"; then
     dnl This is only reasonable to do if crypto actually is there: check for
     dnl SSL libs NOTE: it is important to do this AFTER the crypto lib
 
     AC_CHECK_LIB(ssl, SSL_connect)
 
-    if test "$ac_cv_lib_ssl_SSL_connect" = yes; then
+    if test "$ac_cv_lib_ssl_SSL_connect" = "yes"; then
       dnl Have the libraries--check for OpenSSL headers
       AC_CHECK_HEADERS(openssl/x509.h openssl/rsa.h openssl/crypto.h \
                        openssl/pem.h openssl/ssl.h openssl/err.h,
         ssl_msg="OpenSSL"
-        test openssl != "$DEFAULT_SSL_BACKEND" || VALID_DEFAULT_SSL_BACKEND=yes
+        test "openssl" != "$DEFAULT_SSL_BACKEND" || VALID_DEFAULT_SSL_BACKEND=yes
         OPENSSL_ENABLED=1
         AC_DEFINE(USE_OPENSSL, 1, [if OpenSSL is in use]))
     fi
 
-    if test X"$OPENSSL_ENABLED" != X"1"; then
+    if test "$OPENSSL_ENABLED" != "1"; then
       LIBS="$CLEANLIBS"
     fi
 
-    if test X"$OPT_OPENSSL" != Xoff &&
+    if test "x$OPT_OPENSSL" != "xoff" &&
        test "$OPENSSL_ENABLED" != "1"; then
       AC_MSG_ERROR([OpenSSL libs and/or directories were not found where specified!])
     fi
   fi
 
-  if test X"$OPENSSL_ENABLED" = X"1"; then
+  if test "$OPENSSL_ENABLED" = "1"; then
     dnl These can only exist if OpenSSL exists
 
     AC_MSG_CHECKING([for BoringSSL])
@@ -319,7 +319,7 @@ if test "x$OPT_OPENSSL" != xno; then
       dnl when the ssl shared libs were found in a path that the runtime
       dnl linker does not search through, we need to add it to CURL_LIBRARY_PATH
       dnl to prevent further configure tests to fail due to this
-      if test "x$cross_compiling" != "xyes"; then
+      if test "$cross_compiling" != "yes"; then
         CURL_LIBRARY_PATH="$CURL_LIBRARY_PATH:$LIB_OPENSSL"
         export CURL_LIBRARY_PATH
         AC_MSG_NOTICE([Added $LIB_OPENSSL to CURL_LIBRARY_PATH])
@@ -332,7 +332,7 @@ if test "x$OPT_OPENSSL" != xno; then
   test -z "$ssl_msg" || ssl_backends="${ssl_backends:+$ssl_backends, }$ssl_msg"
 fi
 
-if test X"$OPT_OPENSSL" != Xno &&
+if test "x$OPT_OPENSSL" != "xno" &&
    test "$OPENSSL_ENABLED" != "1"; then
   AC_MSG_NOTICE([OPT_OPENSSL: $OPT_OPENSSL])
   AC_MSG_NOTICE([OPENSSL_ENABLED: $OPENSSL_ENABLED])
@@ -389,7 +389,7 @@ if test "$OPENSSL_ENABLED" = "1"; then
   AC_ARG_ENABLE(openssl-auto-load-config,
 AS_HELP_STRING([--enable-openssl-auto-load-config],[Enable automatic loading of OpenSSL configuration])
 AS_HELP_STRING([--disable-openssl-auto-load-config],[Disable automatic loading of OpenSSL configuration]),
-  [ if test X"$enableval" = X"no"; then
+  [ if test "x$enableval" = "xno"; then
       AC_MSG_NOTICE([automatic loading of OpenSSL configuration disabled])
       AC_DEFINE(CURL_DISABLE_OPENSSL_AUTO_LOAD_CONFIG, 1, [if the OpenSSL configuration will not be loaded automatically])
     fi
diff --git a/m4/curl-rustls.m4 b/m4/curl-rustls.m4
index 7b7e997524..f1b5d6b1df 100644
--- a/m4/curl-rustls.m4
+++ b/m4/curl-rustls.m4
@@ -27,7 +27,7 @@ dnl ----------------------------------------------------
 dnl check for Rustls
 dnl ----------------------------------------------------
 
-if test "x$OPT_RUSTLS" != xno; then
+if test "x$OPT_RUSTLS" != "xno"; then
   ssl_msg=
 
   dnl backup the pre-ssl variables
@@ -83,14 +83,14 @@ if test "x$OPT_RUSTLS" != xno; then
           CPPFLAGS="$CPPFLAGS $addcflags"
         fi
 
-        if test "$curl_cv_apple" = 'yes'; then
+        if test "$curl_cv_apple" = "yes"; then
           RUSTLS_LDFLAGS="-framework Security -framework Foundation"
         else
           RUSTLS_LDFLAGS="-lpthread -ldl -lm"
         fi
 
         LIB_RUSTLS="$PREFIX_RUSTLS/lib$libsuff"
-        if test "$PREFIX_RUSTLS" != "/usr" ; then
+        if test "$PREFIX_RUSTLS" != "/usr"; then
           SSL_LDFLAGS="-L$LIB_RUSTLS $RUSTLS_LDFLAGS"
           SSL_CPPFLAGS="-I$PREFIX_RUSTLS/include"
         fi
@@ -108,7 +108,7 @@ if test "x$OPT_RUSTLS" != xno; then
 
     CURL_CHECK_PKGCONFIG(rustls, [$RUSTLS_PCDIR])
 
-    if test "$PKGCONFIG" != "no" ; then
+    if test "$PKGCONFIG" != "no"; then
       SSL_LIBS=`CURL_EXPORT_PCDIR([$RUSTLS_PCDIR]) dnl
         $PKGCONFIG --libs-only-l --libs-only-other rustls 2>/dev/null`
 
@@ -136,7 +136,7 @@ if test "x$OPT_RUSTLS" != xno; then
       AC_DEFINE(USE_RUSTLS, 1, [if Rustls is enabled])
       USE_RUSTLS="yes"
       RUSTLS_ENABLED=1
-      test rustls != "$DEFAULT_SSL_BACKEND" || VALID_DEFAULT_SSL_BACKEND=yes
+      test "rustls" != "$DEFAULT_SSL_BACKEND" || VALID_DEFAULT_SSL_BACKEND=yes
     else
       AC_MSG_ERROR([pkg-config: Could not find Rustls])
     fi
@@ -152,7 +152,7 @@ if test "x$OPT_RUSTLS" != xno; then
   LDFLAGS="$CLEANLDFLAGS $SSL_LDFLAGS"
   LDFLAGSPC="$CLEANLDFLAGSPC $SSL_LDFLAGS"
 
-  if test "x$USE_RUSTLS" = "xyes"; then
+  if test "$USE_RUSTLS" = "yes"; then
     AC_MSG_NOTICE([detected Rustls])
     check_for_ca_bundle=1
 
@@ -161,7 +161,7 @@ if test "x$OPT_RUSTLS" != xno; then
       dnl linker does not search through, we need to add it to
       dnl CURL_LIBRARY_PATH so that further configure tests do not
       dnl fail due to this
-      if test "x$cross_compiling" != "xyes"; then
+      if test "$cross_compiling" != "yes"; then
         CURL_LIBRARY_PATH="$CURL_LIBRARY_PATH:$LIB_RUSTLS"
         export CURL_LIBRARY_PATH
         AC_MSG_NOTICE([Added $LIB_RUSTLS to CURL_LIBRARY_PATH])
@@ -177,7 +177,7 @@ if test "x$OPT_RUSTLS" != xno; then
         RUSTLS_ENABLED=1
         USE_RUSTLS="yes"
         ssl_msg="Rustls"
-        test rustls != "$DEFAULT_SSL_BACKEND" || VALID_DEFAULT_SSL_BACKEND=yes
+        test "rustls" != "$DEFAULT_SSL_BACKEND" || VALID_DEFAULT_SSL_BACKEND=yes
         ],
         AC_MSG_ERROR([--with-rustls was specified but could not find compatible Rustls.]),
         $RUSTLS_LDFLAGS)
@@ -185,7 +185,7 @@ if test "x$OPT_RUSTLS" != xno; then
 
   test -z "$ssl_msg" || ssl_backends="${ssl_backends:+$ssl_backends, }$ssl_msg"
 
-  if test X"$OPT_RUSTLS" != Xno &&
+  if test "x$OPT_RUSTLS" != "xno" &&
     test "$RUSTLS_ENABLED" != "1"; then
     AC_MSG_NOTICE([OPT_RUSTLS: $OPT_RUSTLS])
     AC_MSG_NOTICE([RUSTLS_ENABLED: $RUSTLS_ENABLED])
diff --git a/m4/curl-schannel.m4 b/m4/curl-schannel.m4
index 1aa66dc2c8..c67098fa11 100644
--- a/m4/curl-schannel.m4
+++ b/m4/curl-schannel.m4
@@ -24,17 +24,17 @@
 
 AC_DEFUN([CURL_WITH_SCHANNEL], [
 AC_MSG_CHECKING([whether to enable Windows native SSL/TLS])
-if test "x$OPT_SCHANNEL" != xno; then
+if test "x$OPT_SCHANNEL" != "xno"; then
   ssl_msg=
   if test "x$OPT_SCHANNEL" != "xno" &&
-     test "x$curl_cv_native_windows" = "xyes"; then
-    if test "$curl_cv_winuwp" = 'yes'; then
+     test "$curl_cv_native_windows" = "yes"; then
+    if test "$curl_cv_winuwp" = "yes"; then
       AC_MSG_ERROR([UWP does not support Schannel.])
     fi
     AC_MSG_RESULT(yes)
     AC_DEFINE(USE_SCHANNEL, 1, [to enable Windows native SSL/TLS support])
     ssl_msg="Schannel"
-    test schannel != "$DEFAULT_SSL_BACKEND" || VALID_DEFAULT_SSL_BACKEND=yes
+    test "schannel" != "$DEFAULT_SSL_BACKEND" || VALID_DEFAULT_SSL_BACKEND=yes
     SCHANNEL_ENABLED=1
     # --with-schannel implies --enable-sspi
     AC_DEFINE(USE_WINDOWS_SSPI, 1, [to enable SSPI support])
diff --git a/m4/curl-sysconfig.m4 b/m4/curl-sysconfig.m4
index f5ebe0391b..7ad1285ef2 100644
--- a/m4/curl-sysconfig.m4
+++ b/m4/curl-sysconfig.m4
@@ -40,7 +40,7 @@ AC_MSG_CHECKING([whether to link macOS CoreFoundation, CoreServices, and SystemC
   ],[
     build_for_macos="no"
   ])
-  if test "x$build_for_macos" != xno; then
+  if test "$build_for_macos" != "no"; then
     AC_MSG_RESULT(yes)
     SYSCONFIG_LDFLAGS='-framework CoreFoundation -framework CoreServices -framework SystemConfiguration'
     LDFLAGS="$LDFLAGS $SYSCONFIG_LDFLAGS"
diff --git a/m4/curl-wolfssl.m4 b/m4/curl-wolfssl.m4
index 0eba972b63..4cbc6f5c0c 100644
--- a/m4/curl-wolfssl.m4
+++ b/m4/curl-wolfssl.m4
@@ -36,14 +36,14 @@ case "$OPT_WOLFSSL" in
     ;;
 esac
 
-if test "x$OPT_WOLFSSL" != xno; then
+if test "$OPT_WOLFSSL" != "no"; then
   _cppflags=$CPPFLAGS
   _ldflags=$LDFLAGS
   _ldflagspc=$LDFLAGSPC
 
   ssl_msg=
 
-  if test X"$OPT_WOLFSSL" != Xno; then
+  if test "$OPT_WOLFSSL" != "no"; then
 
     if test "$OPT_WOLFSSL" = "yes"; then
       OPT_WOLFSSL=""
@@ -56,7 +56,7 @@ if test "x$OPT_WOLFSSL" != xno; then
     addld=""
     addlib=""
     addcflags=""
-    if test "$PKGCONFIG" != "no" ; then
+    if test "$PKGCONFIG" != "no"; then
       addlib=`CURL_EXPORT_PCDIR([$wolfpkg])
         $PKGCONFIG --libs-only-l wolfssl`
       addld=`CURL_EXPORT_PCDIR([$wolfpkg])
@@ -76,13 +76,13 @@ if test "x$OPT_WOLFSSL" != xno; then
       fi
     fi
 
-    if test "$curl_cv_apple" = 'yes'; then
+    if test "$curl_cv_apple" = "yes"; then
       addlib="$addlib -framework Security -framework CoreFoundation"
     else
       addlib="$addlib -lm"
     fi
 
-    if test "x$USE_WOLFSSL" != "xyes"; then
+    if test "$USE_WOLFSSL" != "yes"; then
 
       LDFLAGS="$LDFLAGS $addld"
       LDFLAGSPC="$LDFLAGSPC $addld"
@@ -114,7 +114,7 @@ if test "x$OPT_WOLFSSL" != xno; then
         WOLFSSL_ENABLED=1
         USE_WOLFSSL="yes"
         ssl_msg="wolfSSL"
-        test wolfssl != "$DEFAULT_SSL_BACKEND" || VALID_DEFAULT_SSL_BACKEND=yes
+        test "wolfssl" != "$DEFAULT_SSL_BACKEND" || VALID_DEFAULT_SSL_BACKEND=yes
       ],
       [
         AC_MSG_RESULT(no)
@@ -126,7 +126,7 @@ if test "x$OPT_WOLFSSL" != xno; then
       LIBS="$my_ac_save_LIBS"
     fi
 
-    if test "x$USE_WOLFSSL" = "xyes"; then
+    if test "$USE_WOLFSSL" = "yes"; then
       AC_MSG_NOTICE([detected wolfSSL])
       check_for_ca_bundle=1
 
@@ -150,12 +150,12 @@ if test "x$OPT_WOLFSSL" != xno; then
 
       dnl if this symbol is present, we want the include path to include the
       dnl OpenSSL API root as well
-      if test "x$ac_cv_func_wolfSSL_DES_ecb_encrypt" = 'xyes'; then
+      if test "$ac_cv_func_wolfSSL_DES_ecb_encrypt" = "yes"; then
         HAVE_WOLFSSL_DES_ECB_ENCRYPT=1
       fi
 
       dnl if this symbol is present, we can make use of BIO filter chains
-      if test "x$ac_cv_func_wolfSSL_BIO_new" = 'xyes'; then
+      if test "$ac_cv_func_wolfSSL_BIO_new" = "yes"; then
         HAVE_WOLFSSL_BIO_NEW=1
       fi
 
@@ -164,7 +164,7 @@ if test "x$OPT_WOLFSSL" != xno; then
         dnl linker does not search through, we need to add it to
         dnl CURL_LIBRARY_PATH to prevent further configure tests to fail
         dnl due to this
-        if test "x$cross_compiling" != "xyes"; then
+        if test "$cross_compiling" != "yes"; then
           CURL_LIBRARY_PATH="$CURL_LIBRARY_PATH:$wolfssllibpath"
           export CURL_LIBRARY_PATH
           AC_MSG_NOTICE([Added $wolfssllibpath to CURL_LIBRARY_PATH])
diff --git a/m4/xc-lt-iface.m4 b/m4/xc-lt-iface.m4
index 22eecd349f..83bf62ccf6 100644
--- a/m4/xc-lt-iface.m4
+++ b/m4/xc-lt-iface.m4
@@ -59,8 +59,8 @@ case "x$enable_static" in @%:@ (
     xc_lt_want_enable_static='no'
     ;;
 esac
-if test "x$xc_lt_want_enable_shared" = 'xno' &&
-  test "x$xc_lt_want_enable_static" = 'xno'; then
+if test "$xc_lt_want_enable_shared" = "no" &&
+   test "$xc_lt_want_enable_static" = "no"; then
   AC_MSG_ERROR([can not disable shared and static libraries simultaneously])
 fi
 
@@ -71,8 +71,8 @@ fi
 # must be used in order to build a proper static library.
 #
 
-if test "x$xc_lt_want_enable_shared" = 'xyes' &&
-  test "x$xc_lt_want_enable_static" = 'xyes'; then
+if test "$xc_lt_want_enable_shared" = "yes" &&
+   test "$xc_lt_want_enable_static" = "yes"; then
   case $host_os in @%:@ (
     os2* | aix*)
       xc_lt_want_enable_static='no'
@@ -117,7 +117,7 @@ esac
 # be overridden using 'configure --disable-shared --without-pic'.
 #
 
-if test "x$xc_lt_want_with_pic" = 'xdefault'; then
+if test "$xc_lt_want_with_pic" = "default"; then
   case $host_cpu in @%:@ (
     x86_64 | amd64 | ia64)
       case $host_os in @%:@ (
@@ -229,7 +229,7 @@ m4_define([_XC_CHECK_LT_SHLIB_USE_VERSION_INFO],
 
 AC_MSG_CHECKING([whether to build shared libraries with -version-info])
 xc_lt_shlib_use_version_info='yes'
-if test "x$version_type" = 'xnone'; then
+if test "$version_type" = "none"; then
   xc_lt_shlib_use_version_info='no'
 fi
 case $host_os in @%:@ (
@@ -259,9 +259,9 @@ m4_define([_XC_CHECK_LT_SHLIB_USE_NO_UNDEFINED],
 
 AC_MSG_CHECKING([whether to build shared libraries with -no-undefined])
 xc_lt_shlib_use_no_undefined='no'
-if test "x$allow_undefined" = 'xno'; then
+if test "x$allow_undefined" = "xno"; then
   xc_lt_shlib_use_no_undefined='yes'
-elif test "x$allow_undefined_flag" = 'xunsupported'; then
+elif test "x$allow_undefined_flag" = "xunsupported"; then
   xc_lt_shlib_use_no_undefined='yes'
 fi
 case $host_os in @%:@ (
@@ -293,7 +293,7 @@ AC_MSG_CHECKING([whether to build shared libraries with -mimpure-text])
 xc_lt_shlib_use_mimpure_text='no'
 case $host_os in @%:@ (
   solaris2*)
-    if test "x$GCC" = 'xyes'; then
+    if test "x$GCC" = "xyes"; then
       xc_lt_shlib_use_mimpure_text='yes'
     fi
     ;;
@@ -367,8 +367,8 @@ m4_define([_XC_CHECK_LT_BUILD_SINGLE_VERSION],
 #
 
 AC_MSG_CHECKING([whether to build shared libraries only])
-if test "$xc_lt_build_shared" = 'yes' &&
-  test "$xc_lt_build_static" = 'no'; then
+if test "$xc_lt_build_shared" = "yes" &&
+   test "$xc_lt_build_static" = "no"; then
   xc_lt_build_shared_only='yes'
 else
   xc_lt_build_shared_only='no'
@@ -380,8 +380,8 @@ AC_MSG_RESULT([$xc_lt_build_shared_only])
 #
 
 AC_MSG_CHECKING([whether to build static libraries only])
-if test "$xc_lt_build_static" = 'yes' &&
-  test "$xc_lt_build_shared" = 'no'; then
+if test "$xc_lt_build_static" = "yes" &&
+   test "$xc_lt_build_shared" = "no"; then
   xc_lt_build_static_only='yes'
 else
   xc_lt_build_static_only='no'
diff --git a/m4/xc-val-flgs.m4 b/m4/xc-val-flgs.m4
index 4715163c9e..fd90643496 100644
--- a/m4/xc-val-flgs.m4
+++ b/m4/xc-val-flgs.m4
@@ -39,7 +39,7 @@ AC_DEFUN([_XC_CHECK_VAR_LIBS], [
         ;;
     esac
   done
-  if test $xc_bad_var_libs = yes; then
+  if test "$xc_bad_var_libs" = "yes"; then
     AC_MSG_NOTICE([using LIBS: $LIBS])
     AC_MSG_NOTICE([LIBS note: LIBS should only be used to specify libraries (-lname).])
   fi
@@ -68,7 +68,7 @@ AC_DEFUN([_XC_CHECK_VAR_LDFLAGS], [
         ;;
     esac
   done
-  if test $xc_bad_var_ldflags = yes; then
+  if test "$xc_bad_var_ldflags" = "yes"; then
     AC_MSG_NOTICE([using LDFLAGS: $LDFLAGS])
     xc_bad_var_msg="LDFLAGS note: LDFLAGS should only be used to specify linker flags, not"
     for xc_word in $LDFLAGS; do
@@ -110,7 +110,7 @@ AC_DEFUN([_XC_CHECK_VAR_CPPFLAGS], [
         ;;
     esac
   done
-  if test $xc_bad_var_cppflags = yes; then
+  if test "$xc_bad_var_cppflags" = "yes"; then
     AC_MSG_NOTICE([using CPPFLAGS: $CPPFLAGS])
     xc_bad_var_msg="CPPFLAGS note: CPPFLAGS should only be used to specify C preprocessor flags, not"
     for xc_word in $CPPFLAGS; do
@@ -158,7 +158,7 @@ AC_DEFUN([_XC_CHECK_VAR_CFLAGS], [
         ;;
     esac
   done
-  if test $xc_bad_var_cflags = yes; then
+  if test "$xc_bad_var_cflags" = "yes"; then
     AC_MSG_NOTICE([using CFLAGS: $CFLAGS])
     xc_bad_var_msg="CFLAGS note: CFLAGS should only be used to specify C compiler flags, not"
     for xc_word in $CFLAGS; do
@@ -207,10 +207,10 @@ AC_DEFUN([XC_CHECK_USER_FLAGS], [
   _XC_CHECK_VAR_LDFLAGS
   _XC_CHECK_VAR_CPPFLAGS
   _XC_CHECK_VAR_CFLAGS
-  if test $xc_bad_var_libs = yes ||
-     test $xc_bad_var_cflags = yes ||
-     test $xc_bad_var_ldflags = yes ||
-     test $xc_bad_var_cppflags = yes; then
+  if test "$xc_bad_var_libs" = "yes" ||
+     test "$xc_bad_var_cflags" = "yes" ||
+     test "$xc_bad_var_ldflags" = "yes" ||
+     test "$xc_bad_var_cppflags" = "yes"; then
     AC_MSG_ERROR([Can not continue. Fix errors mentioned immediately above this line.])
   fi
 ])
@@ -235,10 +235,10 @@ AC_DEFUN([XC_CHECK_BUILD_FLAGS], [
   _XC_CHECK_VAR_LDFLAGS
   _XC_CHECK_VAR_CPPFLAGS
   _XC_CHECK_VAR_CFLAGS
-  if test $xc_bad_var_libs = yes ||
-     test $xc_bad_var_cflags = yes ||
-     test $xc_bad_var_ldflags = yes ||
-     test $xc_bad_var_cppflags = yes; then
+  if test "$xc_bad_var_libs" = "yes" ||
+     test "$xc_bad_var_cflags" = "yes" ||
+     test "$xc_bad_var_ldflags" = "yes" ||
+     test "$xc_bad_var_cppflags" = "yes"; then
     AC_MSG_WARN([Continuing even with errors mentioned immediately above this line.])
   fi
 ])
diff --git a/m4/zz40-xc-ovr.m4 b/m4/zz40-xc-ovr.m4
index 5389a45561..02c86c9eea 100644
--- a/m4/zz40-xc-ovr.m4
+++ b/m4/zz40-xc-ovr.m4
@@ -393,7 +393,7 @@ done
 IFS=$xc_tst_prev_IFS
 xc_tst_dirs_sem=`expr "$xc_tst_dirs_sem" : '.*'`
 
-if test $xc_tst_dirs_sem -eq $xc_tst_dirs_col; then
+if test "$xc_tst_dirs_sem" -eq "$xc_tst_dirs_col"; then
   # When both counting methods give the same result we do not want to
   # chose one over the other, and consider auto-detection not possible.
   if test -z "$PATH_SEPARATOR"; then
@@ -404,7 +404,7 @@ if test $xc_tst_dirs_sem -eq $xc_tst_dirs_col; then
   fi
 else
   # Separator with the greater directory count is the auto-detected one.
-  if test $xc_tst_dirs_sem -gt $xc_tst_dirs_col; then
+  if test "$xc_tst_dirs_sem" -gt "$xc_tst_dirs_col"; then
     xc_tst_auto_separator=';'
   else
     xc_tst_auto_separator=':'