configure: Verify that the compiler understands warning cflags

Older compilers don't understand all of the flags

.gitignore

@@ -37,7 +37,6 @@ stamp-h1
 
 # top level stuff
 debian
-m4
 
 # address/ stuff
 address/libaddress.la

agent/Makefile.am

@@ -10,7 +10,7 @@ include $(top_srcdir)/common.mk
 
 AM_CFLAGS = \
 	-DG_LOG_DOMAIN=\"libnice\" \
-	$(ERROR_CFLAGS) \
+	$(LIBNICE_CFLAGS) \
 	$(GLIB_CFLAGS) \
 	$(GUPNP_CFLAGS) \
 	-I $(top_srcdir) \

common.mk

@@ -1,21 +1,3 @@
-
-ERROR_CFLAGS = \
-	$(LIBNICE_CFLAGS) \
-	-fno-strict-aliasing \
-	-Wextra \
-	-Wundef \
-	-Wnested-externs \
-	-Wwrite-strings \
-	-Wpointer-arith \
-	-Wbad-function-cast \
-	-Wmissing-declarations \
-	-Wmissing-prototypes \
-	-Wstrict-prototypes \
-	-Wredundant-decls \
-	-Wno-unused-parameter \
-	-Wno-missing-field-initializers
-# -Wold-style-definition -Winline -Wunreachable-code
-
 CLEANFILES = *.gcno *.gcda
 
 pkgincludedir = $(includedir)/nice

configure.ac

@@ -99,6 +99,25 @@ dnl if asked for, add -Werror if supported
 if test "x$LIBNICE_RELEASE" != "xyes"; then
   LIBNICE_CFLAGS="$LIBNICE_CFLAGS -Werror"
 fi
+
+AC_DEFUN([NICE_ADD_FLAG],
+  AS_COMPILER_FLAG([$1], LIBNICE_CFLAGS="$LIBNICE_CFLAGS $1", [])
+)
+
+NICE_ADD_FLAG([-fno-strict-aliasing])
+NICE_ADD_FLAG([-Wextra])
+NICE_ADD_FLAG([-Wundef])
+NICE_ADD_FLAG([-Wnested-externs])
+NICE_ADD_FLAG([-Wwrite-strings])
+NICE_ADD_FLAG([-Wpointer-arith])
+NICE_ADD_FLAG([-Wbad-function-cast])
+NICE_ADD_FLAG([-Wmissing-declarations])
+NICE_ADD_FLAG([-Wmissing-prototypes])
+NICE_ADD_FLAG([-Wstrict-prototypes])
+NICE_ADD_FLAG([-Wredundant-decls])
+NICE_ADD_FLAG([-Wno-unused-parameter])
+NICE_ADD_FLAG([-Wno-missing-field-initializers])
+
 #
 # Fixes for Solaris
 #

docs/reference/libnice/Makefile.am

@@ -72,7 +72,7 @@ expand_content_files=
 # signals and properties.
 # e.g. INCLUDES=-I$(top_srcdir) -I$(top_builddir) $(GTK_DEBUG_FLAGS)
 # e.g. GTKDOC_LIBS=$(top_builddir)/gtk/$(gtktargetlib)
-AM_CFLAGS =  $(ERROR_CFLAGS) \
+AM_CFLAGS =  $(LIBNICE_CFLAGS) \
         $(GLIB_CFLAGS) \
         -I $(top_srcdir) \
         -I $(top_srcdir)/random \

examples/Makefile.am

@@ -14,7 +14,7 @@ AM_CFLAGS = \
 	-I $(top_srcdir)/random \
 	-I $(top_srcdir)/socket \
 	-I $(top_srcdir)/stun \
-	$(ERROR_CFLAGS) \
+	$(LIBNICE_CFLAGS) \
 	$(GLIB_CFLAGS) \
         $(GUPNP_CFLAGS)
 

m4/as-compiler-flag.m4

@@ -0,0 +1,64 @@
+dnl as-compiler-flag.m4 0.1.0
+
+dnl autostars m4 macro for detection of compiler flags
+
+dnl David Schleef <[email protected]>
+dnl Tim-Philipp Müller <tim centricular net>
+
+dnl AS_COMPILER_FLAG(CFLAGS, ACTION-IF-ACCEPTED, [ACTION-IF-NOT-ACCEPTED])
+dnl Tries to compile with the given CFLAGS.
+dnl Runs ACTION-IF-ACCEPTED if the compiler can compile with the flags,
+dnl and ACTION-IF-NOT-ACCEPTED otherwise.
+
+AC_DEFUN([AS_COMPILER_FLAG],
+[
+  AC_MSG_CHECKING([to see if compiler understands $1])
+
+  save_CFLAGS="$CFLAGS"
+  CFLAGS="$CFLAGS $1"
+
+  AC_TRY_COMPILE([ ], [], [flag_ok=yes], [flag_ok=no])
+  CFLAGS="$save_CFLAGS"
+
+  if test "X$flag_ok" = Xyes ; then
+    $2
+    true
+  else
+    $3
+    true
+  fi
+  AC_MSG_RESULT([$flag_ok])
+])
+
+dnl AS_CXX_COMPILER_FLAG(CPPFLAGS, ACTION-IF-ACCEPTED, [ACTION-IF-NOT-ACCEPTED])
+dnl Tries to compile with the given CPPFLAGS.
+dnl Runs ACTION-IF-ACCEPTED if the compiler can compile with the flags,
+dnl and ACTION-IF-NOT-ACCEPTED otherwise.
+
+AC_DEFUN([AS_CXX_COMPILER_FLAG],
+[
+  AC_REQUIRE([AC_PROG_CXX])
+
+  AC_MSG_CHECKING([to see if c++ compiler understands $1])
+
+  save_CPPFLAGS="$CPPFLAGS"
+  CPPFLAGS="$CPPFLAGS $1"
+
+  AC_LANG_PUSH(C++)
+
+  AC_TRY_COMPILE([ ], [], [flag_ok=yes], [flag_ok=no])
+  CPPFLAGS="$save_CPPFLAGS"
+
+  if test "X$flag_ok" = Xyes ; then
+    $2
+    true
+  else
+    $3
+    true
+  fi
+
+  AC_LANG_POP(C++)
+
+  AC_MSG_RESULT([$flag_ok])
+])
+

nice/Makefile.am

@@ -26,7 +26,7 @@ libnice_la_LDFLAGS = \
 
 
 AM_CFLAGS = \
-	$(ERROR_CFLAGS) \
+	$(LIBNICE_CFLAGS) \
 	$(GLIB_CFLAGS) \
 	-I $(top_srcdir) \
 	-I $(top_srcdir)/agent \

random/Makefile.am

@@ -8,7 +8,7 @@
 
 include $(top_srcdir)/common.mk
 
-AM_CFLAGS = $(ERROR_CFLAGS) $(GLIB_CFLAGS)
+AM_CFLAGS = $(LIBNICE_CFLAGS) $(GLIB_CFLAGS)
 
 noinst_LTLIBRARIES = libnice-random.la
 

socket/Makefile.am

@@ -10,7 +10,7 @@ include $(top_srcdir)/common.mk
 
 AM_CFLAGS = \
 	-DG_LOG_DOMAIN=\"libnice-socket\" \
-	$(ERROR_CFLAGS) \
+	$(LIBNICE_CFLAGS) \
 	$(GLIB_CFLAGS) \
 	$(GUPNP_CFLAGS) \
 	-I $(top_srcdir)/random \

stun/Makefile.am

@@ -10,7 +10,7 @@ SUBDIRS = . tools tests
 
 include $(top_srcdir)/common.mk
 
-AM_CFLAGS = -std=gnu99 -DG_LOG_DOMAIN=\"libnice-stun\" $(ERROR_CFLAGS)
+AM_CFLAGS = -std=gnu99 -DG_LOG_DOMAIN=\"libnice-stun\" $(LIBNICE_CFLAGS)
 AM_CPPFLAGS = -I$(top_srcdir)
 
 if WINDOWS

stun/tools/Makefile.am

@@ -8,7 +8,7 @@
 #
 
 include $(top_srcdir)/common.mk
-AM_CFLAGS = -std=gnu99 $(ERROR_CFLAGS)
+AM_CFLAGS = -std=gnu99 $(LIBNICE_CFLAGS)
 AM_CPPFLAGS = -I$(top_srcdir) 
 
 bin_PROGRAMS = stunbdc stund

tests/Makefile.am

@@ -9,7 +9,7 @@
 include $(top_srcdir)/common.mk
 
 AM_CFLAGS = \
-	$(ERROR_CFLAGS) \
+	$(LIBNICE_CFLAGS) \
 	$(GLIB_CFLAGS) \
         $(GUPNP_CFLAGS) \
 	-I $(top_srcdir) \