117 lines
4.6 KiB
C++
Executable File
117 lines
4.6 KiB
C++
Executable File
/* Macros for declaring functions as non-returning.
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Copyright (C) 2017-2024 Free Software Foundation, Inc.
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This file is free software: you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as
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published by the Free Software Foundation; either version 2.1 of the
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License, or (at your option) any later version.
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This file is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with this program. If not, see <https://www.gnu.org/licenses/>. */
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/* Written by Paul Eggert and Bruno Haible. */
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#ifndef _NORETURN_H
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#define _NORETURN_H 1
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/* A "non-returning" function is a function which cannot return normally.
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It can transfer control only through longjmp(), throw (in C++), or similar
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mechanisms.
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This file defines two macros _GL_NORETURN_FUNC and _GL_NORETURN_FUNCPTR,
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that declare a function to be non-returning.
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_GL_NORETURN_FUNC is for use in function declarations and function
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definitions.
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_GL_NORETURN_FUNCPTR is for use on function pointers.
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Comparison of this file with <stdnoreturn.h>:
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<stdnoreturn.h> defines a macro (or keyword) _Noreturn that declares
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a function to be non-returning. _Noreturn is only for use in function
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declarations and function definitions.
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Therefore, if the non-returning functions you have to declare are unlikely
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to be accessed through function pointers, and if the efficiency with C++
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compilers other than g++, clang, MSVC++ is not an issue to you, you can use
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module 'stdnoreturn' instead of this one, and _Noreturn instead of
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_GL_NORETURN_FUNC.
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*/
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/* Declares that a function is nonreturning.
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Use in C only code:
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_GL_NORETURN_FUNC extern void func (void);
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extern _GL_NORETURN_FUNC void func (void);
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extern void _GL_NORETURN_FUNC func (void);
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Use in C++ only code for a function with C linkage:
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extern "C" { _GL_NORETURN_FUNC void func (void); }
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Use in C++ only code for a function with C++ linkage:
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_GL_NORETURN_FUNC extern void func (void);
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Use in C & C++ code for a function with C linkage:
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#ifdef __cplusplus
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extern "C" {
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#endif
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_GL_NORETURN_FUNC void func (void);
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#ifdef __cplusplus
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}
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#endif
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Use in C & C++ code for a function with current language linkage:
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_GL_NORETURN_FUNC extern void func (void);
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*/
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#if (3 <= __GNUC__ || (__GNUC__ == 2 && 8 <= __GNUC_MINOR__)) \
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|| defined __clang__ \
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|| (0x5110 <= __SUNPRO_C)
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/* For compatibility with _GL_NORETURN_FUNCPTR on clang, use
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__attribute__((__noreturn__)), not _Noreturn. */
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# define _GL_NORETURN_FUNC __attribute__ ((__noreturn__))
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#elif 1200 <= _MSC_VER
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/* Use MSVC specific syntax. */
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# define _GL_NORETURN_FUNC __declspec (noreturn)
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#elif defined __cplusplus
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/* Use ISO C++11 syntax when the compiler supports it. */
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# if (__cplusplus >= 201103 && !(__GNUC__ == 4 && __GNUC_MINOR__ == 7)) \
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|| (_MSC_VER >= 1900)
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# define _GL_NORETURN_FUNC [[noreturn]]
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/* clang++ supports the _Noreturn keyword, but g++ doesn't. */
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# elif defined __clang__
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# define _GL_NORETURN_FUNC _Noreturn
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# else
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# define _GL_NORETURN_FUNC /* empty */
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# endif
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#else
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/* Use ISO C11 syntax when the compiler supports it. */
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# if __STDC_VERSION__ >= 201112 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 7)
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# define _GL_NORETURN_FUNC _Noreturn
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# else
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# define _GL_NORETURN_FUNC /* empty */
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# endif
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#endif
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/* Declares that a function is nonreturning.
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Use in types and declarations that involve function pointers:
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_GL_NORETURN_FUNCPTR void (*funcptr) (void);
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*/
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#if (3 <= __GNUC__ || (__GNUC__ == 2 && 8 <= __GNUC_MINOR__)) \
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|| defined __clang__ \
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|| (0x5110 <= __SUNPRO_C)
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# define _GL_NORETURN_FUNCPTR __attribute__ ((__noreturn__))
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#else
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# define _GL_NORETURN_FUNCPTR /* empty */
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#endif
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/* Comments about the compiler dependent language features:
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- '_Noreturn' - standardized by ISO C11, available in C only (not in C++),
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and not applicable to pointers.
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- '[[noreturn]]' - standardized by ISO C++11, available in C++ only,
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and not applicable to pointers.
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- '__attribute__((__noreturn__))' - available in GCC and clang only,
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both in C and C++.
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- '__declspec(noreturn)' - available in MSVC only,
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both in C and C++, not applicable to pointers.
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*/
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#endif /* _NORETURN_H */
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