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[PATCH] manywarnings: cater to more gcc infelicities
From: |
Eric Blake |
Subject: |
[PATCH] manywarnings: cater to more gcc infelicities |
Date: |
Thu, 6 Sep 2012 15:42:33 -0600 |
Some versions of gcc (at least 4.2.1) noisily warn if
-Wuninitialized is given without -O; in isolation, configure
learns that the warning option is supported, but when later
compiling with -Werror, this makes builds fail. If the
option will have no effect for the configured choice of
$CFLAGS, then it is not worth including in the set.
* m4/manywarnings.m4 (gl_MANYWARN_ALL_GCC): Add test for
-Wuninitialized without -O.
Signed-off-by: Eric Blake <address@hidden>
---
> Oh... and then there's the issue of the multiple WARN_CFLAGS
> variables. coreutils has these three:
>
> GNULIB_TEST_WARN_CFLAGS
> GNULIB_WARN_CFLAGS
> WARN_CFLAGS
>
> Hmm... with that realization, and knowing that those variable names
> are not standardized, the makefile-based approach looks even less
> interesting.
This patch worked for my particular test case; any objections?
ChangeLog | 6 ++++++
m4/manywarnings.m4 | 32 +++++++++++++++++++++++++-------
2 files changed, 31 insertions(+), 7 deletions(-)
diff --git a/ChangeLog b/ChangeLog
index d9f6f89..ec8bc3a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2012-09-06 Eric Blake <address@hidden>
+
+ manywarnings: cater to more gcc infelicities
+ * m4/manywarnings.m4 (gl_MANYWARN_ALL_GCC): Add test for
+ -Wuninitialized without -O.
+
2012-09-05 Eric Blake <address@hidden>
net_if: new module
diff --git a/m4/manywarnings.m4 b/m4/manywarnings.m4
index 2760efb..f3cb23b 100644
--- a/m4/manywarnings.m4
+++ b/m4/manywarnings.m4
@@ -1,4 +1,4 @@
-# manywarnings.m4 serial 4
+# manywarnings.m4 serial 5
dnl Copyright (C) 2008-2012 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
@@ -35,14 +35,12 @@ AC_DEFUN([gl_MANYWARN_COMPLEMENT],
# make sure your gcc understands it.
AC_DEFUN([gl_MANYWARN_ALL_GCC],
[
- dnl First, check if -Wno-missing-field-initializers is needed.
- dnl -Wmissing-field-initializers is implied by -W, but that issues
- dnl warnings with GCC version before 4.7, for the common idiom
- dnl of initializing types on the stack to zero, using { 0, }
+ dnl First, check for some issues that only occur when combining multiple
+ dnl gcc warning categories.
AC_REQUIRE([AC_PROG_CC])
if test -n "$GCC"; then
- dnl First, check -W -Werror -Wno-missing-field-initializers is supported
+ dnl Check if -W -Werror -Wno-missing-field-initializers is supported
dnl with the current $CC $CFLAGS $CPPFLAGS.
AC_MSG_CHECKING([whether -Wno-missing-field-initializers is supported])
AC_CACHE_VAL([gl_cv_cc_nomfi_supported], [
@@ -77,8 +75,24 @@ AC_DEFUN([gl_MANYWARN_ALL_GCC],
])
AC_MSG_RESULT([$gl_cv_cc_nomfi_needed])
fi
+
+ dnl Next, check if -Werror -Wuninitialized is useful with the
+ dnl user's choice of $CFLAGS; some versions of gcc warn that it
+ dnl has no effect if -O is not also used
+ AC_MSG_CHECKING([whether -Wuninitialized is supported])
+ AC_CACHE_VAL([gl_cv_cc_uninitialized_supported], [
+ gl_save_CFLAGS="$CFLAGS"
+ CFLAGS="$CFLAGS -Werror -Wuninitialized"
+ AC_COMPILE_IFELSE(
+ [AC_LANG_PROGRAM([[]], [[]])],
+ [gl_cv_cc_uninitialized_supported=yes],
+ [gl_cv_cc_uninitialized_supported=no])
+ CFLAGS="$gl_save_CFLAGS"])
+ AC_MSG_RESULT([$gl_cv_cc_uninitialized_supported])
+
fi
+ # List all gcc warning categories.
gl_manywarn_set=
for gl_manywarn_item in \
-W \
@@ -197,10 +211,14 @@ AC_DEFUN([gl_MANYWARN_ALL_GCC],
gl_manywarn_set="$gl_manywarn_set $gl_manywarn_item"
done
- # Disable the missing-field-initializers warning if needed
+ # Disable specific options as needed.
if test "$gl_cv_cc_nomfi_needed" = yes; then
gl_manywarn_set="$gl_manywarn_set -Wno-missing-field-initializers"
fi
+ if test "$gl_cv_cc_uninitialized_supported" = no; then
+ gl_manywarn_set="$gl_manywarn_set -Wno-uninitialized"
+ fi
+
$1=$gl_manywarn_set
])
--
1.7.11.4