Hi,
When I compile a gnulib testdir on a glibc system with "gcc -Wall", I see the
following warnings (among others):
argp-help.c: In function 'argp_failure':
argp-help.c:1878:17: warning: assignment makes pointer from integer without a
cast [enabled by default]
This is a dangerous one, because the code assumes a wrong signature of
strerror_r.
To reproduce, it is enough to have the combination of 3 modules:
$ ./gnulib-tool --create-testdir --with-tests --dir=/tmp/testdir
strerror_r-posix argp error
When I look at the preprocessed source code for that compilation unit,
I see some more details:
$ gcc ... -E argp-help.c | grep strerror_r
extern char *strerror_r (int __errnum, char *__buf, size_t __buflen)
extern int rpl_strerror_r (int errnum, char *buf, size_t buflen) __attribute__
((__nonnull__ (2)))
s = rpl_strerror_r (errnum, buf, sizeof buf);
There are two problems:
1) argp-help.c uses STRERROR_R_CHAR_P, which is defined by the macro
AC_FUNC_STRERROR_R, but argp.m4 does not require it (only error.m4 does).
2) When the strerror_r-posix module is in place, the results of
AC_FUNC_STRERROR_R have to be ignored, because they don't reflect the
situation after
#define strerror_r rpl_strerror_r
With the following proposed patches, we arrive at a sane situation without
warning, and
$ gcc ... -E argp-help.c | grep strerror_r
extern char *strerror_r (int __errnum, char *__buf, size_t __buflen)
extern int rpl_strerror_r (int errnum, char *buf, size_t buflen) __attribute__
((__nonnull__ (2)))
if (rpl_strerror_r (errnum, buf, sizeof buf) == 0)
2016-10-16 Bruno Haible <br...@clisp.org>
Make the 'argp' module work without the 'error' module.
* m4/argp.m4 (gl_ARGP): Require AC_FUNC_STRERROR_R.
diff --git a/m4/argp.m4 b/m4/argp.m4
index d36c716..478ec21 100644
--- a/m4/argp.m4
+++ b/m4/argp.m4
@@ -1,4 +1,4 @@
-# argp.m4 serial 14
+# argp.m4 serial 15
dnl Copyright (C) 2003-2016 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
@@ -54,6 +54,7 @@ AC_DEFUN([gl_ARGP],
AC_CHECK_DECLS_ONCE([putchar_unlocked])
AC_CHECK_FUNCS_ONCE([flockfile funlockfile])
AC_CHECK_HEADERS_ONCE([features.h linewrap.h])
+ AC_REQUIRE([AC_FUNC_STRERROR_R])
])
dnl argp-parse.c depends on GNU getopt internals, therefore use GNU getopt
2016-10-16 Bruno Haible <br...@clisp.org>
Fix conflict between strerror_r-posix module and AC_FUNC_STRERROR_R.
* m4/strerror_r.m4 (gl_FUNC_STRERROR_R): Override the values set by the
AC_FUNC_STRERROR_R macro. Define HAVE_DECL_STRERROR_R_ORIG.
* lib/strerror_r.c: Use HAVE_DECL_STRERROR_R_ORIG instead of
HAVE_DECL_STRERROR_R.
diff --git a/lib/strerror_r.c b/lib/strerror_r.c
index 07a00cf..b1d4cf5 100644
--- a/lib/strerror_r.c
+++ b/lib/strerror_r.c
@@ -40,7 +40,7 @@ extern
#endif
int __xpg_strerror_r (int errnum, char *buf, size_t buflen);
-#elif HAVE_DECL_STRERROR_R && !(__GLIBC__ >= 2 || defined __UCLIBC__ ||
defined __CYGWIN__)
+#elif HAVE_DECL_STRERROR_R_ORIG && !(__GLIBC__ >= 2 || defined __UCLIBC__ ||
defined __CYGWIN__)
/* The system's strerror_r function is OK, except that its third argument
is 'int', not 'size_t', or its return type is wrong. */
diff --git a/m4/strerror_r.m4 b/m4/strerror_r.m4
index 2318927..06c51e1 100644
--- a/m4/strerror_r.m4
+++ b/m4/strerror_r.m4
@@ -1,4 +1,4 @@
-# strerror_r.m4 serial 15
+# strerror_r.m4 serial 16
dnl Copyright (C) 2002, 2007-2016 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
@@ -18,6 +18,8 @@ AC_DEFUN([gl_FUNC_STRERROR_R],
if test $ac_cv_have_decl_strerror_r = no; then
HAVE_DECL_STRERROR_R=0
fi
+ AC_DEFINE_UNQUOTED([HAVE_DECL_STRERROR_R_ORIG], [$HAVE_DECL_STRERROR_R],
+ [Define to 1 if you have the declaration of 'strerror_r' in the system
include files, or to 0 otherwise.])
if test $ac_cv_func_strerror_r = yes; then
if test "$ERRNO_H:$REPLACE_STRERROR_0" = :0; then
@@ -36,6 +38,11 @@ AC_DEFUN([gl_FUNC_STRERROR_R],
REPLACE_STRERROR_R=1
fi
fi
+
+ # Overwrite the findings of AC_FUNC_STRERROR_R (for code that uses that).
+ AC_REQUIRE([AC_FUNC_STRERROR_R])
+ AC_DEFINE([HAVE_DECL_STRERROR_R], [1])
+ AC_DEFINE([STRERROR_R_CHAR_P], [0])
])
# Prerequisites of lib/strerror_r.c.
