scc

commit b8ad553523ba96ddf4c363befb1a5397b18af440
parent 7dbb2d53125f9592cf579c0e948c56eb886a8a3c
Author: Roberto E. Vargas Caballero <k0ga@shike2.net>
Date:   Thu, 29 Jan 2026 20:53:34 +0100

cc1: Fold correctly unary in sizeof

When a parenthesis happens after a sizeof it can mean a type name or
an unary expression. The code was correctly detecting the type name
case, but in the unary case it assumed that the unary expresion was
equal to ( expr ) but unary can be also ( expr ) postfix, failling
in cases like:

	sizeof(array)[0]

Diffstat:
M
src/cmd/scc-cc/cc1/expr.c
 | 
47
+++++++++++++++++++++++++----------------------
A
tests/cc/execute/0236-sizeof.c
 | 
8
++++++++
M
tests/cc/execute/scc-tests.lst
 | 
1
+

3 files changed, 34 insertions(+), 22 deletions(-)
diff --git a/src/cmd/scc-cc/cc1/expr.c b/src/cmd/scc-cc/cc1/expr.c
@@ -851,28 +851,6 @@ typeof(Node *np)
 
 static Node *unary(void);
 
-static Type *
-sizeexp(void)
-{
-	Type *tp;
-
-	if (!accept('('))
-		return typeof(unary());
-
-	switch (yytoken) {
-	case TYPE:
-	case TYPEIDEN:
-		tp = typename();
-		break;
-	default:
-		tp = typeof(expr());
-		break;
-	}
-	expect(')');
-
-	return tp;
-}
-
 static Node *
 postfix(Node *lp)
 {
@@ -909,6 +887,31 @@ postfix(Node *lp)
 	}
 }
 
+static Type *
+sizeexp(void)
+{
+	Node *np;
+	Type *tp;
+
+	if (!accept('('))
+		return typeof(unary());
+
+	switch (yytoken) {
+	case TYPE:
+	case TYPEIDEN:
+		tp = typename();
+		expect(')');
+		break;
+	default:
+		np = expr();
+		expect(')');
+		tp = typeof(postfix(np));
+		break;
+	}
+
+	return tp;
+}
+
 static Node *cast(void);
 
 static Node *
diff --git a/tests/cc/execute/0236-sizeof.c b/tests/cc/execute/0236-sizeof.c
@@ -0,0 +1,8 @@
+
+int
+main(void)
+{
+	int nomatches[128];
+
+	return sizeof(nomatches)[0] - sizeof(int);
+}
diff --git a/tests/cc/execute/scc-tests.lst b/tests/cc/execute/scc-tests.lst
@@ -226,3 +226,4 @@
 0233-ifelif.c
 0234-macro.c
 0235-comment.c
+0236-sizeof.c