From: Guillem Jover <guillem@hadrons.org>
Date: Fri, 19 Feb 2021 05:55:17 +0000 (+0100)
Subject: build: Add compiler warnings support
X-Git-Tag: 0.11.4~23
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4f68a88f5519e1bbc8b339dd48882f7f8c613edf;p=thirdparty%2Flibbsd.git

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 c805925..bece823 100644
--- 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 09cb310..1591a93 100644
--- 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
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
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])
+])