preprocessor: Add deferred macros

Deferred macros are needed for C++ modules.  Header units may export
macro definitions and undefinitions.  These are resolved lazily at the
point of (potential) use.  (The language specifies that, it's not just
a useful optimization.)  Thus, identifier nodes grow a 'deferred'
field, which fortunately doesn't expand the structure on 64-bit
systems as there was padding there.  This is non-zero on NT_MACRO
nodes, if the macro is deferred.  When such an identifier is lexed, it
is resolved via a callback that I added recently.  That will either
provide the macro definition, or discover it there was an overriding
undef.  Either way the identifier is no longer a deferred macro.
Notice it is now possible for NT_MACRO nodes to have a NULL macro
expansion.

	libcpp/
	* include/cpplib.h (struct cpp_hashnode): Add deferred field.
	(cpp_set_deferred_macro): Define.
	(cpp_get_deferred_macro): Declare.
	(cpp_macro_definition): Reformat, add overload.
	(cpp_macro_definition_location): Deal with deferred macro.
	(cpp_alloc_token_string, cpp_compare_macro): Declare.
	* internal.h (_cpp_notify_macro_use): Return bool
	(_cpp_maybe_notify_macro_use): Likewise.
	* directives.c (do_undef): Check macro is not undef before
	warning.
	(do_ifdef, do_ifndef): Deal with deferred macro.
	* expr.c (parse_defined): Likewise.
	* lex.c (cpp_allocate_token_string): Break out of ...
	(create_literal): ... here.  Call it.
	(cpp_maybe_module_directive): Deal with deferred macro.
	* macro.c (cpp_get_token_1): Deal with deferred macro.
	(warn_of_redefinition): Deal with deferred macro.
	(compare_macros): Rename to ...
	(cpp_compare_macro): ... here.  Make extern.
	(cpp_get_deferred_macro): New.
	(_cpp_notify_macro_use): Deal with deferred macro, return bool
	indicating definedness.
	(cpp_macro_definition): Deal with deferred macro.

1 files changed, 13 insertions, 5 deletions

diff --git a/libcpp/lex.c b/libcpp/lex.c
index 0f18daf..07d5a4f 100644
--- a/libcpp/lex.c
+++ b/libcpp/lex.c
@@ -1577,13 +1577,20 @@ static void
 create_literal (cpp_reader *pfile, cpp_token *token, const uchar *base,
 		unsigned int len, enum cpp_ttype type)
 {
-  uchar *dest = _cpp_unaligned_alloc (pfile, len + 1);
-
-  memcpy (dest, base, len);
-  dest[len] = '\0';
   token->type = type;
   token->val.str.len = len;
-  token->val.str.text = dest;
+  token->val.str.text = cpp_alloc_token_string (pfile, base, len);
+}
+
+const uchar *
+cpp_alloc_token_string (cpp_reader *pfile,
+			const unsigned char *ptr, unsigned len)
+{
+  uchar *dest = _cpp_unaligned_alloc (pfile, len + 1);
+
+  dest[len] = 0;
+  memcpy (dest, ptr, len);
+  return dest;
 }
 
 /* A pair of raw buffer pointers.  The currently open one is [1], the
@@ -2712,6 +2719,7 @@ cpp_maybe_module_directive (cpp_reader *pfile, cpp_token *result)
 	  /* Don't attempt to expand the token.  */
 	  tok->flags |= NO_EXPAND;
 	  if (_cpp_defined_macro_p (node)
+	      && _cpp_maybe_notify_macro_use (pfile, node, tok->src_loc)
 	      && !cpp_fun_like_macro_p (node))
 	    cpp_error_with_line (pfile, CPP_DL_ERROR, tok->src_loc, 0, 
 				 "module control-line \"%s\" cannot be"