preprocessor: Make __has_include a builtin macro [PR93452]

The clever hack of '#define __has_include __has_include' breaks -dD
and -fdirectives-only, because that emits definitions.  This turns
__has_include into a proper builtin macro.  Thus it's never emitted
via -dD, and because use outside of directive processing is undefined,
we can just expand it anywhere.

	PR preprocessor/93452
	* internal.h (struct spec_nodes): Drop n__has_include{,_next}.
	* directives.c (lex_macro_node): Don't check __has_include redef.
	* expr.c (eval_token): Drop __has_include eval.
	(parse_has_include): Move to ...
	* macro.c (builtin_has_include): ... here.
	(_cpp_builtin_macro_text): Eval __has_include{,_next}.
	* include/cpplib.h (enum cpp_builtin_type): Add BT_HAS_INCLUDE{,_NEXT}.
	* init.c (builtin_array): Add them.
	(cpp_init_builtins): Drop __has_include{,_next} init here ...
	* pch.c (cpp_read_state): ... and here.
	* traditional.c (enum ls): Drop has_include states ...
	(_cpp_scan_out_logical_line): ... and here.

1 files changed, 0 insertions, 2 deletions

diff --git a/libcpp/internal.h b/libcpp/internal.h
index 5453c3b..97d9bdb 100644
--- a/libcpp/internal.h
+++ b/libcpp/internal.h
@@ -290,8 +290,6 @@ struct spec_nodes
   cpp_hashnode *n_false;		/* C++ keyword false */
   cpp_hashnode *n__VA_ARGS__;		/* C99 vararg macros */
   cpp_hashnode *n__VA_OPT__;		/* C++ vararg macros */
-  cpp_hashnode *n__has_include;		/* __has_include operator */
-  cpp_hashnode *n__has_include_next;	/* __has_include_next operator */
 };
 
 typedef struct _cpp_line_note _cpp_line_note;