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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 1736a1bd..00000000 --- a/build-aux/snippet/warn-on-use.h +++ /dev/null | |||
| @@ -1,109 +0,0 @@ | |||
| 1 | /* A C macro for emitting warnings if a function is used. | ||
| 2 | Copyright (C) 2010-2013 Free Software Foundation, Inc. | ||
| 3 | |||
| 4 | This program is free software: you can redistribute it and/or modify it | ||
| 5 | under the terms of the GNU General Public License as published | ||
| 6 | by the Free Software Foundation; either version 3 of the License, or | ||
| 7 | (at your option) any later version. | ||
| 8 | |||
| 9 | This program is distributed in the hope that it will be useful, | ||
| 10 | but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
| 11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | ||
| 12 | General Public License for more details. | ||
| 13 | |||
| 14 | You should have received a copy of the GNU General Public License | ||
| 15 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ | ||
| 16 | |||
| 17 | /* _GL_WARN_ON_USE (function, "literal string") issues a declaration | ||
| 18 | for FUNCTION which will then trigger a compiler warning containing | ||
| 19 | the text of "literal string" anywhere that function is called, if | ||
| 20 | supported by the compiler. If the compiler does not support this | ||
| 21 | feature, the macro expands to an unused extern declaration. | ||
| 22 | |||
| 23 | This macro is useful for marking a function as a potential | ||
| 24 | portability trap, with the intent that "literal string" include | ||
| 25 | instructions on the replacement function that should be used | ||
| 26 | instead. However, one of the reasons that a function is a | ||
| 27 | portability trap is if it has the wrong signature. Declaring | ||
| 28 | FUNCTION with a different signature in C is a compilation error, so | ||
| 29 | this macro must use the same type as any existing declaration so | ||
| 30 | that programs that avoid the problematic FUNCTION do not fail to | ||
| 31 | compile merely because they included a header that poisoned the | ||
| 32 | function. But this implies that _GL_WARN_ON_USE is only safe to | ||
| 33 | use if FUNCTION is known to already have a declaration. Use of | ||
| 34 | this macro implies that there must not be any other macro hiding | ||
| 35 | the declaration of FUNCTION; but undefining FUNCTION first is part | ||
| 36 | of the poisoning process anyway (although for symbols that are | ||
| 37 | provided only via a macro, the result is a compilation error rather | ||
| 38 | than a warning containing "literal string"). Also note that in | ||
| 39 | C++, it is only safe to use if FUNCTION has no overloads. | ||
| 40 | |||
| 41 | For an example, it is possible to poison 'getline' by: | ||
| 42 | - adding a call to gl_WARN_ON_USE_PREPARE([[#include <stdio.h>]], | ||
| 43 | [getline]) in configure.ac, which potentially defines | ||
| 44 | HAVE_RAW_DECL_GETLINE | ||
| 45 | - adding this code to a header that wraps the system <stdio.h>: | ||
| 46 | #undef getline | ||
| 47 | #if HAVE_RAW_DECL_GETLINE | ||
| 48 | _GL_WARN_ON_USE (getline, "getline is required by POSIX 2008, but" | ||
| 49 | "not universally present; use the gnulib module getline"); | ||
| 50 | #endif | ||
| 51 | |||
| 52 | It is not possible to directly poison global variables. But it is | ||
| 53 | possible to write a wrapper accessor function, and poison that | ||
| 54 | (less common usage, like &environ, will cause a compilation error | ||
| 55 | rather than issue the nice warning, but the end result of informing | ||
| 56 | the developer about their portability problem is still achieved): | ||
| 57 | #if HAVE_RAW_DECL_ENVIRON | ||
| 58 | static char ***rpl_environ (void) { return &environ; } | ||
| 59 | _GL_WARN_ON_USE (rpl_environ, "environ is not always properly declared"); | ||
| 60 | # undef environ | ||
| 61 | # define environ (*rpl_environ ()) | ||
| 62 | #endif | ||
| 63 | */ | ||
| 64 | #ifndef _GL_WARN_ON_USE | ||
| 65 | |||
| 66 | # if 4 < __GNUC__ || (__GNUC__ == 4 && 3 <= __GNUC_MINOR__) | ||
| 67 | /* A compiler attribute is available in gcc versions 4.3.0 and later. */ | ||
| 68 | # define _GL_WARN_ON_USE(function, message) \ | ||
| 69 | extern __typeof__ (function) function __attribute__ ((__warning__ (message))) | ||
| 70 | # elif __GNUC__ >= 3 && GNULIB_STRICT_CHECKING | ||
| 71 | /* Verify the existence of the function. */ | ||
| 72 | # define _GL_WARN_ON_USE(function, message) \ | ||
| 73 | extern __typeof__ (function) function | ||
| 74 | # else /* Unsupported. */ | ||
| 75 | # define _GL_WARN_ON_USE(function, message) \ | ||
| 76 | _GL_WARN_EXTERN_C int _gl_warn_on_use | ||
| 77 | # endif | ||
| 78 | #endif | ||
| 79 | |||
| 80 | /* _GL_WARN_ON_USE_CXX (function, rettype, parameters_and_attributes, "string") | ||
| 81 | is like _GL_WARN_ON_USE (function, "string"), except that the function is | ||
| 82 | declared with the given prototype, consisting of return type, parameters, | ||
| 83 | and attributes. | ||
| 84 | This variant is useful for overloaded functions in C++. _GL_WARN_ON_USE does | ||
| 85 | not work in this case. */ | ||
| 86 | #ifndef _GL_WARN_ON_USE_CXX | ||
| 87 | # if 4 < __GNUC__ || (__GNUC__ == 4 && 3 <= __GNUC_MINOR__) | ||
| 88 | # define _GL_WARN_ON_USE_CXX(function,rettype,parameters_and_attributes,msg) \ | ||
| 89 | extern rettype function parameters_and_attributes \ | ||
| 90 | __attribute__ ((__warning__ (msg))) | ||
| 91 | # elif __GNUC__ >= 3 && GNULIB_STRICT_CHECKING | ||
| 92 | /* Verify the existence of the function. */ | ||
| 93 | # define _GL_WARN_ON_USE_CXX(function,rettype,parameters_and_attributes,msg) \ | ||
| 94 | extern rettype function parameters_and_attributes | ||
| 95 | # else /* Unsupported. */ | ||
| 96 | # define _GL_WARN_ON_USE_CXX(function,rettype,parameters_and_attributes,msg) \ | ||
| 97 | _GL_WARN_EXTERN_C int _gl_warn_on_use | ||
| 98 | # endif | ||
| 99 | #endif | ||
| 100 | |||
| 101 | /* _GL_WARN_EXTERN_C declaration; | ||
| 102 | performs the declaration with C linkage. */ | ||
| 103 | #ifndef _GL_WARN_EXTERN_C | ||
| 104 | # if defined __cplusplus | ||
| 105 | # define _GL_WARN_EXTERN_C extern "C" | ||
| 106 | # else | ||
| 107 | # define _GL_WARN_EXTERN_C extern | ||
| 108 | # endif | ||
| 109 | #endif | ||
