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[PATCH] config: Check for and use gcc -Wlogical-op and -Wduplicated-cond.
- From: Mark Wielaard <mjw at redhat dot com>
- To: elfutils-devel at lists dot fedorahosted dot org
- Date: Tue, 09 Feb 2016 16:12:30 +0100
- Subject: [PATCH] config: Check for and use gcc -Wlogical-op and -Wduplicated-cond.
Both -Wlogical-op and -Wduplicated-cond may produce useful warnings.
But we have to check them first. Older versions of gcc had a -Wlogical-op
that warned on some constructs using macros that are not erronious.
Only GCC6 has -Wduplicated-cond.
Signed-off-by: Mark Wielaard <mjw@redhat.com>
---
ChangeLog | 5 +++++
config/ChangeLog | 6 ++++++
config/eu.am | 16 +++++++++++++++-
configure.ac | 22 ++++++++++++++++++++++
4 files changed, 48 insertions(+), 1 deletion(-)
diff --git a/ChangeLog b/ChangeLog
index 637bc13..d206a8e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2016-02-98 Mark Wielaard <mjw@redhat.com>
+
+ * configure.ac: Add checks for sane -Wlogical-op and whether gcc
+ accepts -Wduplicated-cond.
+
2016-01-08 Mark Wielaard <mjw@redhat.com>
* configure.ac: Set version to 0.165.
diff --git a/config/ChangeLog b/config/ChangeLog
index 8e20f1e..8523cb3 100644
--- a/config/ChangeLog
+++ b/config/ChangeLog
@@ -1,3 +1,9 @@
+2016-02-09 Mark Wielaard <mjw@redhat.com>
+
+ * eu.am: Check SANE_LOGICAL_OP_WARNING and
+ HAVE_DUPLICATED_COND_WARNING.
+ (AM_CFLAGS): Add LOGICAL_OP_WARNING and DUPLICATED_COND_WARNING.
+
2016-01-08 Mark Wielaard <mjw@redhat.com>
* elfutils.spec.in: Add elfcompress. Update for 0.165.
diff --git a/config/eu.am b/config/eu.am
index 0095da5..c4e9279 100644
--- a/config/eu.am
+++ b/config/eu.am
@@ -1,6 +1,6 @@
## Common automake fragments for elfutils subdirectory makefiles.
##
-## Copyright (C) 2010, 2014 Red Hat, Inc.
+## Copyright (C) 2010, 2014, 2016 Red Hat, Inc.
##
## This file is part of elfutils.
##
@@ -42,8 +42,22 @@ STACK_USAGE_WARNING=-Wstack-usage=262144
else
STACK_USAGE_WARNING=
endif
+
+if SANE_LOGICAL_OP_WARNING
+LOGICAL_OP_WARNING=-Wlogical-op
+else
+LOGICAL_OP_WARNING=
+endif
+
+if HAVE_DUPLICATED_COND_WARNING
+DUPLICATED_COND_WARNING=-Wduplicated-cond
+else
+DUPLICATED_COND_WARNING=
+endif
+
AM_CFLAGS = -std=gnu99 -Wall -Wshadow -Wformat=2 \
-Wold-style-definition -Wstrict-prototypes \
+ $(LOGICAL_OP_WARNING) $(DUPLICATED_COND_WARNING) \
$(if $($(*F)_no_Werror),,-Werror) \
$(if $($(*F)_no_Wunused),,-Wunused -Wextra) \
$(if $($(*F)_no_Wstack_usage),,$(STACK_USAGE_WARNING)) \
diff --git a/configure.ac b/configure.ac
index 9a3301f..d447db7 100644
--- a/configure.ac
+++ b/configure.ac
@@ -291,6 +291,28 @@ AC_COMPILE_IFELSE([AC_LANG_SOURCE([])],
CFLAGS="$old_CFLAGS"])
AM_CONDITIONAL(ADD_STACK_USAGE_WARNING, [test "x$ac_cv_stack_usage" != "xno"])
+# -Wlogical-op was too fragile in the past, make sure we get a sane one.
+AC_CACHE_CHECK([whether gcc has a sane -Wlogical-op], ac_cv_logical_op, [dnl
+old_CFLAGS="$CFLAGS"
+CFLAGS="$CFLAGS -Wlogical-op -Werror"
+AC_COMPILE_IFELSE([AC_LANG_SOURCE(
+ [#define FLAG 1
+ int f (int r, int f) { return (r && (FLAG || (FLAG & f))); }])],
+ ac_cv_logical_op=yes, ac_cv_logical_op=no)
+CFLAGS="$old_CFLAGS"])
+AM_CONDITIONAL(SANE_LOGICAL_OP_WARNING,
+ [test "x$ac_cv_logical_op" != "xno"])
+
+# -Wduplicated-cond was added by GCC6
+AC_CACHE_CHECK([whether gcc accepts -Wduplicated-cond], ac_cv_duplicated_cond, [dnl
+old_CFLAGS="$CFLAGS"
+CFLAGS="$CFLAGS -Wduplicated-cond"
+AC_COMPILE_IFELSE([AC_LANG_SOURCE([])],
+ ac_cv_duplicated_cond=yes, ac_cv_duplicated_cond=no)
+CFLAGS="$old_CFLAGS"])
+AM_CONDITIONAL(HAVE_DUPLICATED_COND_WARNING,
+ [test "x$ac_cv_duplicated_cond" != "xno"])
+
dnl Check if we have argp available from our libc
AC_LINK_IFELSE(
[AC_LANG_PROGRAM(
--
1.8.3.1