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Diffstat (limited to 'build-aux/snippet/warn-on-use.h')
| -rw-r--r-- | build-aux/snippet/warn-on-use.h | 109 |
1 files changed, 0 insertions, 109 deletions
diff --git a/build-aux/snippet/warn-on-use.h b/build-aux/snippet/warn-on-use.h deleted file mode 100644 index 2948b478..00000000 --- a/build-aux/snippet/warn-on-use.h +++ /dev/null @@ -1,109 +0,0 @@ -/* A C macro for emitting warnings if a function is used. - Copyright (C) 2010-2016 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 - 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 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 |