Don't overwrite built-in macros when redefining them.

This means that we may have both an "invisible" macro _and_ a visible
one in scope, so we need to be a bit more careful about lookup.

We always look up the topmost one (either visible or invisible), and if
it's invisible, that means it is undefined (a builtin macro was first
re-defined, and then that redefinition was undefined).

1 files changed, 19 insertions, 5 deletions

diff --git a/pre-process.c b/pre-process.c
index cb99365..c5d2857 100644
--- a/pre-process.c
+++ b/pre-process.c
@@ -26,6 +26,7 @@
 #include "token.h"
 #include "symbol.h"
 #include "expression.h"
+#include "scope.h"
 
 static int true_nesting = 0;
 static int false_nesting = 0;
@@ -93,10 +94,18 @@ static void replace_with_integer(struct token *token, unsigned int val)
 	token->number = buf;
 }
 
+struct symbol *lookup_macro(struct ident *ident)
+{
+	struct symbol *sym = lookup_symbol(ident, NS_MACRO | NS_INVISIBLEMACRO);
+	if (sym && sym->namespace != NS_MACRO)
+		sym = NULL;
+	return sym;
+}
+
 static int token_defined(struct token *token)
 {
 	if (token_type(token) == TOKEN_IDENT) {
-		struct symbol *sym = lookup_symbol(token->ident, NS_MACRO);
+		struct symbol *sym = lookup_macro(token->ident);
 		if (sym) {
 			sym->weak = 0;
 			return 1;
@@ -125,7 +134,7 @@ static int expand_one_symbol(struct token **list)
 	if (token->pos.noexpand)
 		return 1;
 
-	sym = lookup_symbol(token->ident, NS_MACRO);
+	sym = lookup_macro(token->ident);
 	if (sym) {
 		sym->weak = 0;
 		return expand(list, sym);
@@ -607,7 +616,7 @@ static int already_tokenized(const char *path)
 			continue;
 		if (strcmp(path, s->name))
 			continue;
-		if (!lookup_symbol(s->protect, NS_MACRO))
+		if (!lookup_macro(s->protect))
 			continue;
 		return 1;
 	}
@@ -1080,7 +1089,7 @@ static int do_handle_define(struct stream *stream, struct token **line, struct t
 	if (!expansion)
 		return 1;
 
-	sym = lookup_symbol(name, NS_MACRO);
+	sym = lookup_macro(name);
 	if (sym) {
 		if (token_list_different(sym->expansion, expansion) || 
 		    token_list_different(sym->arglist, arglist)) {
@@ -1091,11 +1100,16 @@ static int do_handle_define(struct stream *stream, struct token **line, struct t
 			warning(left->pos, "preprocessor token %.*s redefined",
 					name->len, name->name);
 			info(sym->pos, "this was the original definition");
+
+			/* Don't overwrite global defs */
+			if (sym->scope != file_scope)
+				goto allocate_new;
 			sym->expansion = expansion;
 			sym->arglist = arglist;
 		}
 		return 1;
 	}
+allocate_new:
 	sym = alloc_symbol(left->pos, SYM_NODE);
 	bind_symbol(sym, name, NS_MACRO);
 
@@ -1134,7 +1148,7 @@ static int handle_undef(struct stream *stream, struct token **line, struct token
 	sym = &left->ident->symbols;
 	while (*sym) {
 		struct symbol *t = *sym;
-		if (t->namespace == NS_MACRO) {
+		if (t->namespace & (NS_MACRO | NS_INVISIBLEMACRO)) {
 			t->namespace = NS_INVISIBLEMACRO;
 			return 1;
 		}