buildroot

From c0f075bdee5edabf8f19b68e0880fbd249a89653 Mon Sep 17 00:00:00 2001

From: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

Date: Sat, 3 Jan 2015 15:09:59 +0100

Subject: [PATCH] Add test for -Wunused-but-set-variable

​

The -Wunused-but-set-variable option does not exist in some old gcc

versions (gcc 4.5.x), so using it unconditionally breaks the build

with such compilers.

​

This commit introduces the AX_CHECK_COMPILE_FLAG m4 macro taken from

the autoconf-archive

(http://git.savannah.gnu.org/gitweb/?p=autoconf-archive.git;a=blob_plain;f=m4/ax_check_compile_flag.m4),

and uses it to detect if the -Wunused-but-set-variable option is

supported, and only uses it in this case.

​

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

(rebased against v0.1.0)

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>

---

 Makefile.am                 |  2 +-

 configure.ac                |  3 ++

 m4/ax_check_compile_flag.m4 | 74 +++++++++++++++++++++++++++++++++++++++++++++

 3 files changed, 78 insertions(+), 1 deletion(-)

 create mode 100644 m4/ax_check_compile_flag.m4

​

diff --git a/Makefile.am b/Makefile.am

index 5d23e0b..0f51f6a 100644

--- a/Makefile.am

+++ b/Makefile.am

@@ -6,7 +6,7 @@ AM_CFLAGS = \

    -Wnested-externs -Wstrict-prototypes -Wunsafe-loop-optimizations \

    -Wwrite-strings -Wno-missing-field-initializers -Wno-unused-parameter \

    -Wcast-align -Wformat-nonliteral -Wformat-security -Wswitch-default \

-   -Wmissing-include-dirs -Wno-aggregate-return -Wunused-but-set-variable \

+   -Wmissing-include-dirs -Wno-aggregate-return @GCC_WARN_UNUSED_BUT_SET@ \

    -Warray-bounds -Wold-style-definition -Wsign-compare -Wlarger-than=65537

 AM_CFLAGS += -Wno-undef  # sophiasip is not -Wundef--safe

 AM_CFLAGS += -Wno-redundant-decls  # sophiasip also contains redundant declarations

diff --git a/configure.ac b/configure.ac

index 17870a7..f9bb1e4 100644

--- a/configure.ac

+++ b/configure.ac

@@ -7,6 +7,9 @@ AM_SILENT_RULES([yes])

 AC_GNU_SOURCE

 AC_PROG_CC

+AX_CHECK_COMPILE_FLAG([-Wunused-but-set-variable],

+   [GCC_WARN_UNUSED_BUT_SET=-Wunused-but-set-variable])

+AC_SUBST(GCC_WARN_UNUSED_BUT_SET)

 LT_PREREQ([2.2])

 LT_INIT

diff --git a/m4/ax_check_compile_flag.m4 b/m4/ax_check_compile_flag.m4

new file mode 100644

index 0000000..51df0c0

--- /dev/null

+++ b/m4/ax_check_compile_flag.m4

@@ -0,0 +1,74 @@

+# ===========================================================================

+#   http://www.gnu.org/software/autoconf-archive/ax_check_compile_flag.html

+# ===========================================================================

+#

+# SYNOPSIS