From ad1539d5555a161cf6851de8995641d6dfe792d9 Mon Sep 17 00:00:00 2001 From: Martin Sebor Date: Mon, 28 Oct 2019 22:46:28 +0000 Subject: PR c/66970 - Add __has_builtin() macro gcc/ChangeLog: PR c/66970 * doc/cpp.texi (__has_builtin): Document. * doc/extend.texi (__builtin_frob_return_addr): Correct spelling. gcc/c/ChangeLog: PR c/66970 * c-decl.c (names_builtin_p): Define a new function. gcc/c-family/ChangeLog: PR c/66970 * c-common.c (c_common_nodes_and_builtins): Call c_define_builtins even when only preprocessing. * c-common.h (names_builtin_p): Declare new function. * c-lex.c (init_c_lex): Set has_builtin. (c_common_has_builtin): Define a new function. * c-ppoutput.c (init_pp_output): Set has_builtin. gcc/cp/ChangeLog: PR c/66970 * cp-objcp-common.c (names_builtin_p): Define new function. gcc/testsuite/ChangeLog: PR c/66970 * c-c++-common/cpp/has-builtin-2.c: New test. * c-c++-common/cpp/has-builtin-3.c: New test. * c-c++-common/cpp/has-builtin.c: New test. From-SVN: r277544 --- gcc/doc/cpp.texi | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) (limited to 'gcc/doc/cpp.texi') diff --git a/gcc/doc/cpp.texi b/gcc/doc/cpp.texi index f2de39a..bd741ce 100644 --- a/gcc/doc/cpp.texi +++ b/gcc/doc/cpp.texi @@ -3159,6 +3159,7 @@ directive}: @samp{#if}, @samp{#ifdef} or @samp{#ifndef}. * Elif:: * @code{__has_attribute}:: * @code{__has_cpp_attribute}:: +* @code{__has_builtin}:: * @code{__has_include}:: @end menu @@ -3478,6 +3479,33 @@ information including the dates of the introduction of current standard attributes, see @w{@uref{https://isocpp.org/std/standing-documents/sd-6-sg10-feature-test-recommendations/, SD-6: SG10 Feature Test Recommendations}}. +@node @code{__has_builtin} +@subsection @code{__has_builtin} +@cindex @code{__has_builtin} + +The special operator @code{__has_builtin (@var{operand})} may be used in +constant integer contexts and in preprocessor @samp{#if} and @samp{#elif} +expressions to test whether the symbol named by its @var{operand} is +recognized as a built-in function by GCC in the current language and +conformance mode. It evaluates to a constant integer with a nonzero +value if the argument refers to such a function, and to zero otherwise. +The operator may also be used in preprocessor @samp{#if} and @samp{#elif} +expressions. The @code{__has_builtin} operator by itself, without any +@var{operand} or parentheses, acts as a predefined macro so that support +for it can be tested in portable code. Thus, the recommended use of +the operator is as follows: + +@smallexample +#if defined __has_builtin +# if __has_builtin (__builtin_object_size) +# define builtin_object_size(ptr) __builtin_object_size (ptr, 2) +# endif +#endif +#ifndef builtin_object_size +# define builtin_object_size(ptr) ((size_t)-1) +#endif +@end smallexample + @node @code{__has_include} @subsection @code{__has_include} @cindex @code{__has_include} -- cgit v1.1