kc3-lang/gnulib/doc/noreturn.texi

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• Hash : 077ffc1e
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  Date : 2021-01-09T14:17:32
  

  snippet/_Noreturn: port to pedantic clang
  
  Problem reported by Joe Nelson in:
  https://lists.gnu.org/r/bug-gnulib/2021-01/msg00152.html
  * doc/noreturn.texi: Improve.
  * lib/_Noreturn.h (_Noreturn):
  * m4/gnulib-common.m4 (gl_COMMON_BODY):
  Do not assume _Noreturn works as-is when __STRICT_ANSI__ is
  defined, unless __STDC_VERSION__ indicates C11 or later.
  * lib/_Noreturn.h (_Noreturn): Fall back on __attribute__
  ((__noreturn__)) if Clang; this merges the
  2020-08-10T23:53:13Zbruno@clisp.org patch to m4/gnulib-common.m4.
  

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• doc/noreturn.texi

• @c GNU noreturn, stdnoreturn modules documentation
  
  @c Copyright (C) 2019--2021 Free Software Foundation, Inc.
  
  @c Permission is granted to copy, distribute and/or modify this document
  @c under the terms of the GNU Free Documentation License, Version 1.3 or
  @c any later version published by the Free Software Foundation; with no
  @c Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.  A
  @c copy of the license is at <https://www.gnu.org/licenses/fdl-1.3.en.html>.
  
  @node Non-returning Functions
  @section Non-returning Functions
  
  @cindex @code{_Noreturn}
  @cindex @code{noreturn}
  @cindex @code{stdnoreturn}
  A "non-returning" function is a function which cannot return normally.
  It can transfer control only through @code{longjmp()}, @code{throw}
  (in C++), or similar mechanisms.  The most prominent function of this
  class is the @code{abort} function.  Non-returning functions are
  declared with a @code{void} return type.
  
  It helps the compiler's ability to emit sensible warnings, following
  data-flow analysis, to declare which functions are non-returning.
  
  To decorate function declarations and function definitions, you can
  use the @code{_Noreturn} keyword.  No modules are needed, as Gnulib
  arranges for @code{<config.h>} to define @code{_Noreturn} to an
  appropriate replacement on platforms lacking it.
  
  Gnulib has two modules that support such a declaration:
  
  @itemize @bullet
  @item
  The @samp{noreturn} module.  It provides a way to put this declaration
  at function declarations, at function definitions, and in function
  pointer types.  The identifiers to use are:
  @itemize -
  @item
  @code{_GL_NORETURN_FUNC} for use in function declarations and function
  definitions.
  @item
  @code{_GL_NORETURN_FUNCPTR} for use on function pointers.
  @end itemize
  @noindent
  The include file is @code{<noreturn.h>}.
  
  @item
  The @samp{stdnoreturn} module.  This can improve readability by
  letting you use @code{noreturn} instead of @code{_Noreturn};
  unfortunately, @code{noreturn} is a no-op on some platforms even
  though @code{_Noreturn} works on them.  The include file is
  @code{<stdnoreturn.h>}.
  @end itemize
  
  Which of the two modules to use?  If the non-returning functions you
  have to declare are unlikely to be accessed through function pointers,
  you should use module @code{stdnoreturn}; otherwise the module
  @code{noreturn} provides for better data-flow analysis and thus for
  better warnings.
  
  For a detailed description of the @code{stdnoreturn} module, see
  @ref{stdnoreturn.h}.
  

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