build: Add compiler warnings support

Detect as many warnings as possible during configure and enable them
if the user did not supply any, so that any such problem can be spotted
and fixed.

diff --git a/.gitignore b/.gitignore
index c80592553957d6e3f27d76dfe623a6416f0a2893..bece8239441a8aa5ed0b573ffd0c5ab06cb70c89 100644 (file)
--- a/.gitignore
+++ b/.gitignore
@@ -20,5 +20,4 @@ build-aux/
 configure
 config.*
 libtool
-m4/
 stamp-h1

diff --git a/configure.ac b/configure.ac
index 09cb31029521752106606c5adff7fdd98f99aeb6..1591a93526d46115fab35670aecc52b504c2a45a 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -52,9 +52,45 @@ AC_PROG_INSTALL
 AC_PROG_LN_S
 
 # Set default compiler variables
-if test "$user_CFLAGS" = unset && test "$GCC" = yes; then
-  CFLAGS="$CFLAGS -Wall -Wextra -Wno-unused-variable -Wno-unused-parameter"
-fi
+AS_IF([test "$user_CFLAGS" = unset], [
+  LIBBSD_CHECK_COMPILER_FLAG([-Wall])
+  LIBBSD_CHECK_COMPILER_FLAG([-Wextra])
+
+  LIBBSD_CHECK_COMPILER_FLAG([-Wbad-function-cast])
+  LIBBSD_CHECK_COMPILER_FLAG([-Wc99-c11-compat])
+  LIBBSD_CHECK_COMPILER_FLAG([-Wcast-align])
+  LIBBSD_CHECK_COMPILER_FLAG([-Wdeclaration-after-statement])
+  LIBBSD_CHECK_COMPILER_FLAG([-Wdocumentation])
+  LIBBSD_CHECK_COMPILER_FLAG([-Wduplicated-branches])
+  LIBBSD_CHECK_COMPILER_FLAG([-Wduplicated-cond])
+  LIBBSD_CHECK_COMPILER_FLAG([-Wformat -Wformat-security])
+  LIBBSD_CHECK_COMPILER_FLAG([-Wformat=2])
+  LIBBSD_CHECK_COMPILER_FLAG([-Winit-self])
+  LIBBSD_CHECK_COMPILER_FLAG([-Wlogical-not-parentheses])
+  LIBBSD_CHECK_COMPILER_FLAG([-Wlogical-op])
+  LIBBSD_CHECK_COMPILER_FLAG([-Wmissing-declarations])
+  LIBBSD_CHECK_COMPILER_FLAG([-Wmissing-format-attribute])
+  LIBBSD_CHECK_COMPILER_FLAG([-Wmissing-prototypes])
+  LIBBSD_CHECK_COMPILER_FLAG([-Wnested-externs])
+  LIBBSD_CHECK_COMPILER_FLAG([-Wno-missing-field-initializers])
+  LIBBSD_CHECK_COMPILER_FLAG([-Wno-nonnull-compare])
+  LIBBSD_CHECK_COMPILER_FLAG([-Wno-tautological-constant-out-of-range-compare])
+  LIBBSD_CHECK_COMPILER_FLAG([-Wno-unused-parameter])
+  LIBBSD_CHECK_COMPILER_FLAG([-Wnull-dereference])
+  LIBBSD_CHECK_COMPILER_FLAG([-Wold-style-definition])
+  LIBBSD_CHECK_COMPILER_FLAG([-Wpointer-arith])
+  LIBBSD_CHECK_COMPILER_FLAG([-Wregister])
+  LIBBSD_CHECK_COMPILER_FLAG([-Wrestrict])
+  LIBBSD_CHECK_COMPILER_FLAG([-Wshadow])
+  LIBBSD_CHECK_COMPILER_FLAG([-Wshift-negative-value])
+  LIBBSD_CHECK_COMPILER_FLAG([-Wsizeof-array-argument])
+  LIBBSD_CHECK_COMPILER_FLAG([-Wstrict-prototypes])
+  LIBBSD_CHECK_COMPILER_FLAG([-Wswitch-bool])
+  LIBBSD_CHECK_COMPILER_FLAG([-Wvla])
+  LIBBSD_CHECK_COMPILER_FLAG([-Wwrite-strings])
+
+  CFLAGS="$CFLAGS $LIBBSD_COMPILER_FLAGS"
+])
 
 # Checks for libraries.
 AC_CHECK_LIB([testu01], [unif01_CreateExternGenBits],

diff --git a/m4/.gitignore b/m4/.gitignore
new file mode 100644 (file)
index 0000000..10fb5d4
--- /dev/null
+++ b/m4/.gitignore
@@ -0,0 +1,2 @@
+*.m4
+!libbsd*.m4

diff --git a/m4/libbsd-compiler.m4 b/m4/libbsd-compiler.m4
new file mode 100644 (file)
index 0000000..b655b83
--- /dev/null
+++ b/m4/libbsd-compiler.m4
@@ -0,0 +1,24 @@
+# Copyright © 2021 Guillem Jover <guillem@hadrons.org>
+
+# LIBBSD_CHECK_COMPILER_FLAG
+# -------------------------
+AC_DEFUN([LIBBSD_CHECK_COMPILER_FLAG], [
+  AS_VAR_PUSHDEF([libbsd_varname_cache], [libbsd_cv_cflags_$1])
+  AC_CACHE_CHECK([whether $CC accepts $1], [libbsd_varname_cache], [
+    m4_define([libbsd_check_flag], m4_bpatsubst([$1], [^-Wno-], [-W]))
+    AS_VAR_COPY([libbsd_save_CFLAGS], [CFLAGS])
+    AS_VAR_SET([CFLAGS], ["-Werror libbsd_check_flag"])
+    AC_COMPILE_IFELSE([
+      AC_LANG_SOURCE([[]])
+    ], [
+      AS_VAR_SET([libbsd_varname_cache], [yes])
+    ], [
+      AS_VAR_SET([libbsd_varname_cache], [no])
+    ])
+    AS_VAR_COPY([CFLAGS], [libbsd_save_CFLAGS])
+  ])
+  AS_VAR_IF([libbsd_varname_cache], [yes], [
+    AS_VAR_APPEND([LIBBSD_COMPILER_FLAGS], [" $1"])
+  ])
+  AS_VAR_POPDEF([libbsd_varname_cache])
+])