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build: disable warnings that trigger known clang problems

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Fixes build with clang 3.5 on Fedora 21.
This commit is contained in:
Lubomir Rintel
2015-03-18 19:02:29 +01:00
parent 3ccc6f290d
commit f0740aff88
1 changed files with 64 additions and 16 deletions
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80
m4/compiler_warnings.m4
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@@ -1,3 +1,24 @@
dnl Check whether a particular compiler flag works with code provided,
dnl disable it in CFLAGS if the check fails.
AC_DEFUN([NM_COMPILER_WARNING], [
CFLAGS_SAVED="$CFLAGS"
CFLAGS="$CFLAGS -Werror -W$1"
AC_MSG_CHECKING(whether -W$1 works)
AC_COMPILE_IFELSE([AC_LANG_SOURCE([[]])], [
AC_COMPILE_IFELSE([AC_LANG_SOURCE([[$2]])], [
AC_MSG_RESULT(yes)
CFLAGS="$CFLAGS_SAVED -W$1"
],[
AC_MSG_RESULT(no)
CFLAGS="$CFLAGS_SAVED -Wno-$1"
])
],[
AC_MSG_RESULT(not supported)
CFLAGS="$CFLAGS_SAVED"
])
])
AC_DEFUN([NM_COMPILER_WARNINGS],
[AC_ARG_ENABLE(more-warnings,
AS_HELP_STRING([--enable-more-warnings], [Possible values: no/yes/error]),
@@ -5,22 +26,26 @@ AC_DEFUN([NM_COMPILER_WARNINGS],
AC_MSG_CHECKING(for more warnings)
if test "$GCC" = "yes" -a "$set_more_warnings" != "no"; then
AC_MSG_RESULT(yes)
dnl This is enabled in clang by default, makes little sense,
dnl and causes the build to abort with -Werror.
CFLAGS_SAVED="$CFLAGS"
CFLAGS_MORE_WARNINGS="-Wall -std=gnu89"
CFLAGS="$CFLAGS -Qunused-arguments"
AC_COMPILE_IFELSE([AC_LANG_SOURCE([])], [], CFLAGS="$CFLAGS_SAVED")
unset CFLAGS_SAVED
dnl clang only warns about unknown warnings, unless
dnl called with "-Werror=unknown-warning-option"
dnl Test if the compiler supports that, and if it does
dnl attach it to the CFLAGS.
CFLAGS_EXTRA="-Werror=unknown-warning-option"
CFLAGS="$CFLAGS_MORE_WARNINGS $CFLAGS_EXTRA $CFLAGS_SAVED"
AC_TRY_COMPILE([], [],
has_option=yes,
has_option=no,)
if test $has_option = no; then
CFLAGS_EXTRA=
NM_COMPILER_WARNING([unknown-warning-option], [])
CFLAGS_SAVED="$CFLAGS"
CFLAGS_MORE_WARNINGS="-Wall -std=gnu89"
if test "x$set_more_warnings" = xerror; then
CFLAGS_MORE_WARNINGS="$CFLAGS_MORE_WARNINGS -Werror"
fi
unset has_option
for option in -Wshadow -Wmissing-declarations -Wmissing-prototypes \
-Wdeclaration-after-statement -Wformat-security \
@@ -31,8 +56,8 @@ if test "$GCC" = "yes" -a "$set_more_warnings" != "no"; then
-Wpointer-arith -Winit-self \
-Wmissing-include-dirs -Wno-pragmas; do
dnl GCC 4.4 does not warn when checking for -Wno-* flags (https://gcc.gnu.org/wiki/FAQ#wnowarning)
CFLAGS="$CFLAGS_MORE_WARNINGS $CFLAGS_EXTRA $(printf '%s' "$option" | sed 's/^-Wno-/-W/') $CFLAGS_SAVED"
AC_MSG_CHECKING([whether gcc understands $option])
CFLAGS="$CFLAGS_MORE_WARNINGS $(printf '%s' "$option" | sed 's/^-Wno-/-W/') $CFLAGS_SAVED"
AC_MSG_CHECKING([whether compiler understands $option])
AC_TRY_COMPILE([], [],
has_option=yes,
has_option=no,)
@@ -43,12 +68,35 @@ if test "$GCC" = "yes" -a "$set_more_warnings" != "no"; then
unset has_option
done
unset option
unset CFLAGS_EXTRA
if test "x$set_more_warnings" = xerror; then
CFLAGS_MORE_WARNINGS="$CFLAGS_MORE_WARNINGS -Werror"
fi
CFLAGS="$CFLAGS_MORE_WARNINGS $CFLAGS_SAVED"
CFLAGS="$CFLAGS_SAVED"
unset CFLAGS_SAVED
dnl Disable warnings triggered by known compiler problems
dnl https://bugzilla.gnome.org/show_bug.cgi?id=745821
NM_COMPILER_WARNING([unknown-attributes], [#include <glib.h>])
dnl https://llvm.org/bugs/show_bug.cgi?id=21614
NM_COMPILER_WARNING([array-bounds],
[#include <string.h>]
[void f () { strcmp ("something", "0"); }]
)
dnl https://llvm.org/bugs/show_bug.cgi?id=22949
NM_COMPILER_WARNING([parentheses-equality],
[#include <sys/wait.h>]
[void f () { if (WIFCONTINUED(0)) return; }]
)
dnl systemd-dhcp's log_internal macro and our handle_warn are sometimes
dnl used in void context,u sometimes in int. Makes clang unhappy.
NM_COMPILER_WARNING([unused-value],
[#define yolo ({ (666 + 666); })]
[int f () { int i = yolo; yolo; return i; }]
)
CFLAGS="$CFLAGS_MORE_WARNINGS $CFLAGS"
else
AC_MSG_RESULT(no)
fi