autoconf: remove 'deeper' checks for `AC_CHECK_FUNCS`

The net effect of the deeper checks is to raise implicit function decls
on modern compilers.

These checks appear to have been added ~20 years ago, relating to an
unverifiable claim about HP-UX. Autoconf support for the platform has
grown in leaps and bounds since.

It didn't cause a real problem here, but when investigating a FP this
came up. No evidence has been identified that this was actually broken
in the past, and there is no evidence that this is necessary now.

`-Werror=implicit-function-declarations` is enabled for both checks;
without a working prototype they will both fail regardless. In the
second case there will in fact never be a working prototype and
therefore it will always fail unconditionally.

`AC_CHECK_FUNCS` does effectively the same thing as the removed checks,
except it actually defines a dummy prototype to see if it links.

If `AC_CHECK_FUNCS` is broken on a given platform we have bigger
problems than trying to build cURL. This should also be faster.

Bug: https://bugs.gentoo.org/932827
Reviewed-By: Eli Schwartz <eschwartz93@gmail.com>
Closes #13830

diff --git a/configure.ac b/configure.ac
index 85f0ab599b69a237b9b405aac45128d13575684a..57c57741b68cb671ec5578d6e6ec8ff5813f38e7 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -3800,26 +3800,6 @@ AC_CHECK_FUNCS([\
   snprintf \
   utime \
   utimes \
-],[
-],[
-  func="$ac_func"
-  eval skipcheck=\$skipcheck_$func
-  if test "x$skipcheck" != "xyes"; then
-    AC_MSG_CHECKING([deeper for $func])
-    AC_LINK_IFELSE([
-      AC_LANG_PROGRAM([[
-      ]],[[
-        $func ();
-      ]])
-    ],[
-      AC_MSG_RESULT([yes])
-      eval "ac_cv_func_$func=yes"
-      AC_DEFINE_UNQUOTED(XC_SH_TR_CPP([HAVE_$func]), [1],
-        [Define to 1 if you have the $func function.])
-    ],[
-      AC_MSG_RESULT([but still no])
-    ])
-  fi
 ])
 
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