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Diffstat (limited to 'lib/noreturn.h')
| -rw-r--r-- | lib/noreturn.h | 111 |
1 files changed, 111 insertions, 0 deletions
diff --git a/lib/noreturn.h b/lib/noreturn.h new file mode 100644 index 0000000000..353a1e41b0 --- /dev/null +++ b/lib/noreturn.h @@ -0,0 +1,111 @@ +/* Macros for declaring functions as non-returning. + + Copyright (C) 2017 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/>. */ + +/* Written by Paul Eggert and Bruno Haible. */ + +#ifndef _NORETURN_H +#define _NORETURN_H 1 + +/* A "non-returning" function is a function which cannot return normally. + It can transfer control only through longjmp(), throw (in C++), or similar + mechanisms. + + This file defines two macros _GL_NORETURN_FUNC and _GL_NORETURN_FUNCPTR, + that declare a function to be non-returning. + _GL_NORETURN_FUNC is for use in function declarations and function + definitions. + _GL_NORETURN_FUNCPTR is for use on function pointers. + + Comparison of this file with <stdnoreturn.h>: + <stdnoreturn.h> defines a macro (or keyword) _Noreturn that declares + a function to be non-returning. _Noreturn is only for use in function + declarations and function definitions. + Therefore, if the non-returning functions you have to declare are unlikely + to be accessed through function pointers, and if the efficiency with C++ + compilers other than g++, clang, MSVC++ is not an issue to you, you can use + module 'stdnoreturn' instead of this one, and _Noreturn instead of + _GL_NORETURN_FUNC. + */ + +/* Declares that a function is nonreturning. + Use in C only code: + _GL_NORETURN_FUNC extern void func (void); + extern _GL_NORETURN_FUNC void func (void); + extern void _GL_NORETURN_FUNC func (void); + Use in C++ only code for a function with C linkage: + extern "C" { _GL_NORETURN_FUNC void func (void); } + Use in C++ only code for a function with C++ linkage: + _GL_NORETURN_FUNC extern void func (void); + Use in C & C++ code for a function with C linkage: + #ifdef __cplusplus + extern "C" { + #endif + _GL_NORETURN_FUNC void func (void); + #ifdef __cplusplus + } + #endif + Use in C & C++ code for a function with current language linkage: + _GL_NORETURN_FUNC extern void func (void); + */ +#if (3 <= __GNUC__ || (__GNUC__ == 2 && 8 <= __GNUC_MINOR__)) \ + || (0x5110 <= __SUNPRO_C) + /* For compatibility with _GL_NORETURN_FUNCPTR on clang, use + __attribute__((__noreturn__)), not _Noreturn. */ +# define _GL_NORETURN_FUNC __attribute__ ((__noreturn__)) +#elif 1200 <= _MSC_VER + /* Use MSVC specific syntax. */ +# define _GL_NORETURN_FUNC __declspec (noreturn) +#elif defined __cplusplus + /* Use ISO C++11 syntax when the compiler supports it. */ +# if (__cplusplus >= 201103 && !(__GNUC__ == 4 && __GNUC_MINOR__ == 7)) \ + || (_MSC_VER >= 1900) +# define _GL_NORETURN_FUNC [[noreturn]] +# else +# define _GL_NORETURN_FUNC /* empty */ +# endif +#else + /* Use ISO C11 syntax when the compiler supports it. */ +# if __STDC_VERSION__ >= 201112 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 7) +# define _GL_NORETURN_FUNC _Noreturn +# else +# define _GL_NORETURN_FUNC /* empty */ +# endif +#endif + +/* Declares that a function is nonreturning. + Use in types and declarations that involve function pointers: + _GL_NORETURN_FUNCPTR void (*funcptr) (void); + */ +#if (3 <= __GNUC__ || (__GNUC__ == 2 && 8 <= __GNUC_MINOR__)) \ + || (0x5110 <= __SUNPRO_C) +# define _GL_NORETURN_FUNCPTR __attribute__ ((__noreturn__)) +#else +# define _GL_NORETURN_FUNCPTR /* empty */ +#endif + +/* Comments about the compiler dependent language features: + - '_Noreturn' - standardized by ISO C11, available in C only (not in C++), + and not applicable to pointers. + - '[[noreturn]]' - standardized by ISO C++11, available in C++ only, + and not applicable to pointers. + - '__attribute__((__noreturn__))' - available in GCC and clang only, + both in C and C++. + - '__declspec(noreturn)' - available in MSVC only, + both in C and C++, not applicable to pointers. + */ + +#endif /* _NORETURN_H */ |