Merge GDB 7.5.1

gdb/gnulib/extra/warn-on-use.h

-/* A C macro for emitting warnings if a function is used.
-   Copyright (C) 2010, 2011 Free Software Foundation, Inc.
-
-   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
-   Lesser 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/>.  */
-
-/* _GL_WARN_ON_USE (function, "literal string") issues a declaration
-   for FUNCTION which will then trigger a compiler warning containing
-   the text of "literal string" anywhere that function is called, if
-   supported by the compiler.  If the compiler does not support this
-   feature, the macro expands to an unused extern declaration.
-
-   This macro is useful for marking a function as a potential
-   portability trap, with the intent that "literal string" include
-   instructions on the replacement function that should be used
-   instead.  However, one of the reasons that a function is a
-   portability trap is if it has the wrong signature.  Declaring
-   FUNCTION with a different signature in C is a compilation error, so
-   this macro must use the same type as any existing declaration so
-   that programs that avoid the problematic FUNCTION do not fail to
-   compile merely because they included a header that poisoned the
-   function.  But this implies that _GL_WARN_ON_USE is only safe to
-   use if FUNCTION is known to already have a declaration.  Use of
-   this macro implies that there must not be any other macro hiding
-   the declaration of FUNCTION; but undefining FUNCTION first is part
-   of the poisoning process anyway (although for symbols that are
-   provided only via a macro, the result is a compilation error rather
-   than a warning containing "literal string").  Also note that in
-   C++, it is only safe to use if FUNCTION has no overloads.
-
-   For an example, it is possible to poison 'getline' by:
-   - adding a call to gl_WARN_ON_USE_PREPARE([[#include <stdio.h>]],
-     [getline]) in configure.ac, which potentially defines
-     HAVE_RAW_DECL_GETLINE
-   - adding this code to a header that wraps the system <stdio.h>:
-     #undef getline
-     #if HAVE_RAW_DECL_GETLINE
-     _GL_WARN_ON_USE (getline, "getline is required by POSIX 2008, but"
-       "not universally present; use the gnulib module getline");
-     #endif
-
-   It is not possible to directly poison global variables.  But it is
-   possible to write a wrapper accessor function, and poison that
-   (less common usage, like &environ, will cause a compilation error
-   rather than issue the nice warning, but the end result of informing
-   the developer about their portability problem is still achieved):
-   #if HAVE_RAW_DECL_ENVIRON
-   static inline char ***rpl_environ (void) { return &environ; }
-   _GL_WARN_ON_USE (rpl_environ, "environ is not always properly declared");
-   # undef environ
-   # define environ (*rpl_environ ())
-   #endif
-   */
-#ifndef _GL_WARN_ON_USE
-
-# if 4 < __GNUC__ || (__GNUC__ == 4 && 3 <= __GNUC_MINOR__)
-/* A compiler attribute is available in gcc versions 4.3.0 and later.  */
-#  define _GL_WARN_ON_USE(function, message) \
-extern __typeof__ (function) function __attribute__ ((__warning__ (message)))
-# elif __GNUC__ >= 3 && GNULIB_STRICT_CHECKING
-/* Verify the existence of the function.  */
-#  define _GL_WARN_ON_USE(function, message) \
-extern __typeof__ (function) function
-# else /* Unsupported.  */
-#  define _GL_WARN_ON_USE(function, message) \
-_GL_WARN_EXTERN_C int _gl_warn_on_use
-# endif
-#endif
-
-/* _GL_WARN_ON_USE_CXX (function, rettype, parameters_and_attributes, "string")
-   is like _GL_WARN_ON_USE (function, "string"), except that the function is
-   declared with the given prototype, consisting of return type, parameters,
-   and attributes.
-   This variant is useful for overloaded functions in C++. _GL_WARN_ON_USE does
-   not work in this case.  */
-#ifndef _GL_WARN_ON_USE_CXX
-# if 4 < __GNUC__ || (__GNUC__ == 4 && 3 <= __GNUC_MINOR__)
-#  define _GL_WARN_ON_USE_CXX(function,rettype,parameters_and_attributes,msg) \
-extern rettype function parameters_and_attributes \
-     __attribute__ ((__warning__ (msg)))
-# elif __GNUC__ >= 3 && GNULIB_STRICT_CHECKING
-/* Verify the existence of the function.  */
-#  define _GL_WARN_ON_USE_CXX(function,rettype,parameters_and_attributes,msg) \
-extern rettype function parameters_and_attributes
-# else /* Unsupported.  */
-#  define _GL_WARN_ON_USE_CXX(function,rettype,parameters_and_attributes,msg) \
-_GL_WARN_EXTERN_C int _gl_warn_on_use
-# endif
-#endif
-
-/* _GL_WARN_EXTERN_C declaration;
-   performs the declaration with C linkage.  */
-#ifndef _GL_WARN_EXTERN_C
-# if defined __cplusplus
-#  define _GL_WARN_EXTERN_C extern "C"
-# else
-#  define _GL_WARN_EXTERN_C extern
-# endif
-#endif