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

1 files changed, 28 insertions, 0 deletions

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}