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| -rw-r--r-- | doc/info/chap/language-facilities.texinfo | 41 |
1 files changed, 41 insertions, 0 deletions
diff --git a/doc/info/chap/language-facilities.texinfo b/doc/info/chap/language-facilities.texinfo index 687d485..c82f104 100644 --- a/doc/info/chap/language-facilities.texinfo +++ b/doc/info/chap/language-facilities.texinfo @@ -6,6 +6,7 @@ @menu * Alternative tokens:: Alternative spellings of common operators. * Booleans:: Proper booleans in the C programming language. +* Non-returning functions:: Specifying that functions never return. @end menu @@ -119,3 +120,43 @@ The macros @code{bool}, @code{true}, and @code{false} may be removed and become built-in the future; or at least, the right to undefined them may be removed. + + +@node Non-returning functions +@section Non-returning functions + +@hfindex stdnoreturn.h +@cpindex Non-returning functions +@cpindex @code{noreturn} +@cpindex @code{_Noreturn} +@tpindex noreturn +@tpindex _Noreturn +A few, such as @code{exit}, functions never return, +and cannot fail. The @sc{ISO}@tie{}C11 added a +function qualifier that lets you specify that a +functon never returns, that is, the process exits +or changes process image before returning. Note +that this is not the same thing only returning on +failure, like the @code{exec} functions. This +qualifier is known as @code{_Noreturn} and must be +used at the beginning the the function declaration. + +By including the header file @file{<stdnoreturn.h>}, +the macro definition @code{noreturn} is made +available as an alias for @code{_Noreturn} . + +@lvindex __noreturn_is_defined +Note that @code{slibc}, in contrast to some C +standard libraries, does not defined, the +non-standardised, @code{__noreturn_is_defined} macro. + +Some compilers have supported this before +@sc{ISO}@tie{}C11, by specifying the function +attribute @code{noreturn}. Note that including the +@file{<stdnoreturn.h>} header file conflicts with +this compiler feature. Because of this, +@file{<stdnoreturn.h>} is considered non-portable +by @code{slibc}. If you want to use both, GCC +supports @code{__attribute__((__noreturn__))} as +a synonym for @code{__attribute__((noreturn))}. + |