preproc: smacro argument lists can't be preceded by space

The smacro argument list cannot be preceded by whitespace, or we
wouldn't be able to define no-argument smacros the expansion of which
starts with (.

Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>

1 files changed, 8 insertions, 4 deletions

diff --git a/asm/preproc.c b/asm/preproc.c
index 125fa100..a3f8b7de 100644
--- a/asm/preproc.c
+++ b/asm/preproc.c
@@ -2320,10 +2320,14 @@ static int parse_smacro_template(Token ***tpp, SMacro *tmpl)
     Token *t = *tn;
     Token *name;
 
-    while (t && t->type == TOK_WHITESPACE) {
-        tn = &t->next;
-        t = *tn;
-    }
+    /*
+     * DO NOT skip whitespace here, or we won't be able to distinguish:
+     *
+     * %define foo (a,b)		; no arguments, (a,b) is the expansion
+     * %define bar(a,b)			; two arguments, empty expansion
+     *
+     * This ambiguity was inherited from C.
+     */
 
     if (!tok_is_(t, "("))
         goto finish;