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binutils-gdb/gdbsupport/common-defs.h
Simon Marchi ff8885c3be gdbsupport: include cstdlib in common-defs.h 
In PR 25731 [1], the following build failure was reported:

    ../../binutils-gdb/gdb/gdbtypes.c:1254:10: error: no member named 'abs' in namespace 'std'; did you mean simply 'abs'?
                = ((std::abs (stride) * element_count) + 7) / 8;
                    ^~~~~~~~
                    abs
    /usr/include/stdlib.h:129:6: note: 'abs' declared here
    int      abs(int) __pure2;
             ^
The original report was using:

    $ gcc -v
    Apple LLVM version 8.0.0 (clang-800.0.42.1)
    Target: x86_64-apple-darwin15.6.0

Note that I was _not_ able to reproduce using:

    $ g++ --version
    Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/c++/4.2.1
    Apple clang version 11.0.0 (clang-1100.0.33.17)
    Target: x86_64-apple-darwin19.3.0

The proposed fix is to include <cstdlib> in addition to <stdlib.h>.

Here's an excerpt of [2] relevant to this problem:

    These headers [speaking of the .h form] are allowed to also declare
    the same names in the std namespace, and the corresponding cxxx
    headers are allowed to also declare the same names in the global
    namespace: including <cstdlib> definitely provides std::malloc and
    may also provide ::malloc.  Including <stdlib.h> definitely provides
    ::malloc and may also provide std::malloc

Since we use std::abs, we should not assume that our include of stdlib.h
declares an `abs` function in the `std` namespace.

If we replace the include of stdlib.h with cstdlib, then we fall in the
opposite situation.  A standard C++ library may decide to only put the
declarations in the std namespace, requiring us to prefix all standard
functions with `std::`.  I'm not against that, but for the moment I think the
safest way forward is to just include both.

Note that I don't know what effect this patch can have on any stdlib.h fix
provided by gnulib.

[1] https://sourceware.org/bugzilla/show_bug.cgi?id=25731
[2] https://en.cppreference.com/w/cpp/header#C_compatibility_headers

gdbsupport/ChangeLog:

	* common-defs.h: Include cstdlib.h.
2020-04-27 09:28:03 -04:00

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/* Common definitions.
Copyright (C) 1986-2020 Free Software Foundation, Inc.
This file is part of GDB.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#ifndef COMMON_COMMON_DEFS_H
#define COMMON_COMMON_DEFS_H
#include <gdbsupport/config.h>
#undef PACKAGE_NAME
#undef PACKAGE
#undef PACKAGE_VERSION
#undef PACKAGE_STRING
#undef PACKAGE_TARNAME
#include "gnulib/config.h"
/* From:
https://www.gnu.org/software/gnulib/manual/html_node/stdint_002eh.html
"On some hosts that predate C++11, when using C++ one must define
__STDC_CONSTANT_MACROS to make visible the definitions of constant
macros such as INTMAX_C, and one must define __STDC_LIMIT_MACROS to
make visible the definitions of limit macros such as INTMAX_MAX.".
And:
https://www.gnu.org/software/gnulib/manual/html_node/inttypes_002eh.html
"On some hosts that predate C++11, when using C++ one must define
__STDC_FORMAT_MACROS to make visible the declarations of format
macros such as PRIdMAX."
Must do this before including any system header, since other system
headers may include stdint.h/inttypes.h. */
#define __STDC_CONSTANT_MACROS 1
#define __STDC_LIMIT_MACROS 1
#define __STDC_FORMAT_MACROS 1
/* Some distros enable _FORTIFY_SOURCE by default, which on occasion
has caused build failures with -Wunused-result when a patch is
developed on a distro that does not enable _FORTIFY_SOURCE. We
enable it here in order to try to catch these problems earlier;
plus this seems like a reasonable safety measure. The check for
optimization is required because _FORTIFY_SOURCE only works when
optimization is enabled. If _FORTIFY_SOURCE is already defined,
then we don't do anything. Also, on MinGW, fortify requires
linking to -lssp, and to avoid the hassle of checking for
that and linking to it statically, we just don't define
_FORTIFY_SOURCE there. */
#if (!defined _FORTIFY_SOURCE && defined __OPTIMIZE__ && __OPTIMIZE__ > 0 \
&& !defined(__MINGW32__))
#define _FORTIFY_SOURCE 2
#endif
/* We don't support Windows versions before XP, so we define
_WIN32_WINNT correspondingly to ensure the Windows API headers
expose the required symbols. */
#if defined (__MINGW32__) || defined (__CYGWIN__)
# ifdef _WIN32_WINNT
# if _WIN32_WINNT < 0x0501
# undef _WIN32_WINNT
# define _WIN32_WINNT 0x0501
# endif
# else
# define _WIN32_WINNT 0x0501
# endif
#endif /* __MINGW32__ || __CYGWIN__ */
#include <stdarg.h>
#include <stdio.h>
/* Include both cstdlib and stdlib.h to ensure we have standard functions
defined both in the std:: namespace and in the global namespace. */
#include <cstdlib>
#include <stdlib.h>
#include <stddef.h>
#include <stdint.h>
#include <string.h>
#ifdef HAVE_STRINGS_H
#include <strings.h> /* for strcasecmp and strncasecmp */
#endif
#include <errno.h>
#if HAVE_ALLOCA_H
#include <alloca.h>
#endif
#include "ansidecl.h"
/* This is defined by ansidecl.h, but we prefer gnulib's version. On
MinGW, gnulib might enable __USE_MINGW_ANSI_STDIO, which may or not
require use of attribute gnu_printf instead of printf. gnulib
checks that at configure time. Since _GL_ATTRIBUTE_FORMAT_PRINTF
is compatible with ATTRIBUTE_PRINTF, simply use it. */
#undef ATTRIBUTE_PRINTF
#define ATTRIBUTE_PRINTF _GL_ATTRIBUTE_FORMAT_PRINTF
#if GCC_VERSION >= 3004
#define ATTRIBUTE_UNUSED_RESULT __attribute__ ((__warn_unused_result__))
#else
#define ATTRIBUTE_UNUSED_RESULT
#endif
#include "libiberty.h"
#include "pathmax.h"
#include "gdb/signals.h"
#include "gdb_locale.h"
#include "ptid.h"
#include "common-types.h"
#include "common-utils.h"
#include "gdb_assert.h"
#include "errors.h"
#include "print-utils.h"
#include "common-debug.h"
#include "cleanups.h"
#include "common-exceptions.h"
#include "gdbsupport/poison.h"
#define EXTERN_C extern "C"
#define EXTERN_C_PUSH extern "C" {
#define EXTERN_C_POP }
/* Pull in gdb::unique_xmalloc_ptr. */
#include "gdbsupport/gdb_unique_ptr.h"
/* String containing the current directory (what getwd would return). */
extern char *current_directory;
/* sbrk on macOS is not useful for our purposes, since sbrk(0) always
returns the same value. brk/sbrk on macOS is just an emulation
that always returns a pointer to a 4MB section reserved for
that. */
#if defined (HAVE_SBRK) && !__APPLE__
#define HAVE_USEFUL_SBRK 1
#endif
#endif /* COMMON_COMMON_DEFS_H */
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