build-sys: never set CFLAGS and LDFLAGSwip

These variables are supposed to be set by user. What we can do in
configure is to set another variable and AC_SUBST() it. Then in
Makefile.am we assign it to AM_{CFLAGS,LDFLAGS}. This way user can
always override their values, in configure or make phase.

Reference: http://www.gnu.org/software/automake/manual/html_node/Flag-Variables-Ordering.html

3 files changed, 75 insertions, 121 deletions

diff --git a/Makefile.am b/Makefile.am
index b2a46fa..68d2bd1 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -14,14 +14,8 @@ AM_CPPFLAGS = \
 	-DLIBEXECDIR=\""$(libexecdir)"\" \
 	${zlib_CFLAGS}
 
-AM_CFLAGS = \
-	-fvisibility=hidden \
-	-ffunction-sections \
-	-fdata-sections
-
-AM_LDFLAGS = \
-	-Wl,--gc-sections \
-	-Wl,--as-needed
+AM_CFLAGS = $(WARNINGFLAGS)
+AM_LDFLAGS = $(GCLDFLAGS)
 
 SED_PROCESS = \
 	$(AM_V_GEN)$(MKDIR_P) $(dir $@) && $(SED) \
diff --git a/configure.ac b/configure.ac
index 72df628..b7ea29b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -113,54 +113,56 @@ AM_CONDITIONAL([ENABLE_GTK_DOC], false)])
 # Default CFLAGS and LDFLAGS
 #####################################################################
 
-CC_CHECK_CFLAGS_APPEND([ \
-			-pipe \
-			-DANOTHER_BRICK_IN_THE \
-			-Wall \
-			-W \
-			-Wextra \
-			-Wno-inline \
-			-Wvla \
-			-Wundef \
-			-Wformat=2 \
-			-Wlogical-op \
-			-Wsign-compare \
-			-Wformat-security \
-			-Wmissing-include-dirs \
-			-Wformat-nonliteral \
-			-Wold-style-definition \
-			-Wpointer-arith \
-			-Winit-self \
-			-Wdeclaration-after-statement \
-			-Wfloat-equal \
-			-Wmissing-prototypes \
-			-Wstrict-prototypes \
-			-Wredundant-decls \
-			-Wmissing-declarations \
-			-Wmissing-noreturn \
-			-Wshadow \
-			-Wendif-labels \
-			-Wstrict-aliasing=2 \
-			-Wwrite-strings \
-			-Wno-long-long \
-			-Wno-overlength-strings \
-			-Wno-unused-parameter \
-			-Wno-missing-field-initializers \
-			-Wno-unused-result \
-			-Wnested-externs \
-			-Wchar-subscripts \
-			-Wtype-limits \
-			-Wuninitialized \
-			-fno-common \
-			-fdiagnostics-show-option \
-			-fvisibility=hidden \
-			-ffunction-sections \
-			-fdata-sections])
-
-CC_CHECK_LDFLAGS_APPEND([ \
-			 -Wl,--as-needed \
-			 -Wl,--gc-sections])
-
+CC_CHECK_FLAGS_APPEND(with_cflags, [CFLAGS], [\
+		       -pipe \
+		       -DANOTHER_BRICK_IN_THE \
+		       -Wall \
+		       -W \
+		       -Wextra \
+		       -Wno-inline \
+		       -Wvla \
+		       -Wundef \
+		       -Wformat=2 \
+		       -Wlogical-op \
+		       -Wsign-compare \
+		       -Wformat-security \
+		       -Wmissing-include-dirs \
+		       -Wformat-nonliteral \
+		       -Wold-style-definition \
+		       -Wpointer-arith \
+		       -Winit-self \
+		       -Wdeclaration-after-statement \
+		       -Wfloat-equal \
+		       -Wmissing-prototypes \
+		       -Wstrict-prototypes \
+		       -Wredundant-decls \
+		       -Wmissing-declarations \
+		       -Wmissing-noreturn \
+		       -Wshadow \
+		       -Wendif-labels \
+		       -Wstrict-aliasing=2 \
+		       -Wwrite-strings \
+		       -Wno-long-long \
+		       -Wno-overlength-strings \
+		       -Wno-unused-parameter \
+		       -Wno-missing-field-initializers \
+		       -Wno-unused-result \
+		       -Wnested-externs \
+		       -Wchar-subscripts \
+		       -Wtype-limits \
+		       -Wuninitialized \
+		       -fno-common \
+		       -fdiagnostics-show-option \
+		       -fvisibility=hidden \
+		       -ffunction-sections \
+		       -fdata-sections])
+AC_SUBST([WARNINGFLAGS], $with_warningflags)
+
+
+CC_CHECK_FLAGS_APPEND([with_ldflags], [LDFLAGS], [ \
+		       -Wl,--as-needed \
+		       -Wl,--gc-sections])
+AC_SUBST([GCLDFLAGS], $with_ldflags)
 
 #####################################################################
 # Generate files from *.in
@@ -191,8 +193,8 @@ AC_MSG_RESULT([
 	bindir:			${bindir}
 
 	compiler:		${CC}
-	cflags:			${CFLAGS}
-	ldflags:		${LDFLAGS}
+	cflags:			${with_cflags} ${CFLAGS}
+	ldflags:		${with_ldflags} ${LDFLAGS}
 
 	tools:			${enable_tools}
 	logging:		${enable_logging}
diff --git a/m4/attributes.m4 b/m4/attributes.m4
index 20d05e4..c80ae62 100644
--- a/m4/attributes.m4
+++ b/m4/attributes.m4
@@ -1,6 +1,7 @@
 dnl Macros to check the presence of generic (non-typed) symbols.
 dnl Copyright (c) 2006-2008 Diego Pettenò <flameeyes@gmail.com>
 dnl Copyright (c) 2006-2008 xine project
+dnl Copyright (c) 2012 Lucas De Marchi <lucas.de.marchi@gmail.com>
 dnl
 dnl This program is free software; you can redistribute it and/or modify
 dnl it under the terms of the GNU General Public License as published by
@@ -32,58 +33,34 @@ dnl distribute a modified version of the Autoconf Macro, you may extend
 dnl this special exception to the GPL to apply to your modified version as
 dnl well.
 
-dnl Check if the flag is supported by compiler
-dnl CC_CHECK_CFLAGS_SILENT([FLAG], [ACTION-IF-FOUND],[ACTION-IF-NOT-FOUND])
-
-AC_DEFUN([CC_CHECK_CFLAGS_SILENT], [
-  AC_CACHE_VAL(AS_TR_SH([cc_cv_cflags_$1]),
-    [ac_save_CFLAGS="$CFLAGS"
-     CFLAGS="$CFLAGS $1"
-     AC_COMPILE_IFELSE([AC_LANG_SOURCE([int a;])],
-       [eval "AS_TR_SH([cc_cv_cflags_$1])='yes'"],
-       [eval "AS_TR_SH([cc_cv_cflags_$1])='no'"])
-     CFLAGS="$ac_save_CFLAGS"
-    ])
-
-  AS_IF([eval test x$]AS_TR_SH([cc_cv_cflags_$1])[ = xyes],
-    [$2], [$3])
+dnl Check if flag in a envvar is supported by compiler and append
+dnl "backup" variable
+dnl CC_CHECK_FLAG_APPEND([WHERE-TO-APPEND], [ENV-VAR], [FLAG])
+AC_DEFUN([CC_CHECK_FLAG_APPEND], [
+  AC_CACHE_CHECK([if $CC supports flag $3 in envvar $2],
+                 AS_TR_SH([cc_cv_$2_$3]),
+		 [eval "AS_TR_SH([cc_save_$2])='${$2}'"
+		  eval "AS_TR_SH([$2])='$3'"
+		  AC_COMPILE_IFELSE([AC_LANG_SOURCE([int a = 0; int main(void) { return a; } ])],
+                                    [eval "AS_TR_SH([cc_cv_$2_$3])='yes'"],
+                                    [eval "AS_TR_SH([cc_cv_$2_$3])='no'"])
+		  eval "AS_TR_SH([$2])='$cc_save_$2'"])
+
+  AS_IF([eval test x$]AS_TR_SH([cc_cv_$2_$3])[ = xyes],
+        [eval "$1='${$1} $3'"])
 ])
 
-dnl Check if the flag is supported by compiler (cacheable)
-dnl CC_CHECK_CFLAGS([FLAG], [ACTION-IF-FOUND],[ACTION-IF-NOT-FOUND])
-
-AC_DEFUN([CC_CHECK_CFLAGS], [
-  AC_CACHE_CHECK([if $CC supports $1 flag],
-    AS_TR_SH([cc_cv_cflags_$1]),
-    CC_CHECK_CFLAGS_SILENT([$1]) dnl Don't execute actions here!
-  )
-
-  AS_IF([eval test x$]AS_TR_SH([cc_cv_cflags_$1])[ = xyes],
-    [$2], [$3])
+dnl CC_CHECK_FLAGS_APPEND([WHERE-TO-APPEND], [ENV-VAR], [FLAG1 FLAG2])
+AC_DEFUN([CC_CHECK_FLAGS_APPEND], [
+  for flag in $3; do
+    CC_CHECK_FLAG_APPEND($1, $2, $flag)
+  done
 ])
 
-dnl CC_CHECK_CFLAG_APPEND(FLAG, [action-if-found], [action-if-not-found])
-dnl Check for CFLAG and appends them to CFLAGS if supported
-AC_DEFUN([CC_CHECK_CFLAG_APPEND], [
-  AC_CACHE_CHECK([if $CC supports $1 flag],
-    AS_TR_SH([cc_cv_cflags_$1]),
-    CC_CHECK_CFLAGS_SILENT([$1]) dnl Don't execute actions here!
-  )
-
-  AS_IF([eval test x$]AS_TR_SH([cc_cv_cflags_$1])[ = xyes],
-    [CFLAGS="$CFLAGS $1"; DEBUG_CFLAGS="$DEBUG_CFLAGS $1"; $2], [$3])
-])
 
-dnl CC_CHECK_CFLAGS_APPEND([FLAG1 FLAG2], [action-if-found], [action-if-not])
-AC_DEFUN([CC_CHECK_CFLAGS_APPEND], [
-  for flag in $1; do
-    CC_CHECK_CFLAG_APPEND($flag, [$2], [$3])
-  done
-])
 
 dnl Check if the flag is supported by linker
 dnl CC_CHECK_LDFLAGS_SILENT([FLAG], [ACTION-IF-FOUND],[ACTION-IF-NOT-FOUND])
-
 AC_DEFUN([CC_CHECK_LDFLAGS_SILENT], [
   AC_CACHE_VAL(AS_TR_SH([cc_cv_ldflags_$1]),
     [ac_save_LDFLAGS="$LDFLAGS"
@@ -111,25 +88,6 @@ AC_DEFUN([CC_CHECK_LDFLAGS], [
     [$2], [$3])
 ])
 
-dnl CC_CHECK_LDFLAG_APPEND(FLAG, [action-if-found], [action-if-not-found])
-dnl Check for LDFLAG and appends them to LDFLAGS if supported
-AC_DEFUN([CC_CHECK_LDFLAG_APPEND], [
-  AC_CACHE_CHECK([if $CC supports $1 flag],
-    AS_TR_SH([cc_cv_ldflags_$1]),
-    CC_CHECK_LDFLAGS_SILENT([$1]) dnl Don't execute actions here!
-  )
-
-  AS_IF([eval test x$]AS_TR_SH([cc_cv_ldflags_$1])[ = xyes],
-    [LDFLAGS="$LDFLAGS $1"; DEBUG_LDFLAGS="$DEBUG_LDFLAGS $1"; $2], [$3])
-])
-
-dnl CC_CHECK_LDFLAGS_APPEND([FLAG1 FLAG2], [action-if-found], [action-if-not])
-AC_DEFUN([CC_CHECK_LDFLAGS_APPEND], [
-  for flag in $1; do
-    CC_CHECK_LDFLAG_APPEND($flag, [$2], [$3])
-  done
-])
-
 dnl define the LDFLAGS_NOUNDEFINED variable with the correct value for
 dnl the current linker to avoid undefined references in a shared object.
 AC_DEFUN([CC_NOUNDEFINED], [