ww: cgen trap batch (def-str field, chained-ptr write, scalar+str tuple ABI)

selfhost/cmd/wcc/cgenutil.ww

@@ -599,6 +599,23 @@ fn structlookup(c: *cgen, name: str) *structinfo = {
 
 // primsize — size in bytes of a primitive type name (or 0 if not
 // recognised as a primitive — the caller falls back to other paths).
+// fldnumidx — parse a tuple field name like "0" / "1" / "12" into an
+// index, or -1 if not all-digits. Used by cgdot to dispatch
+// `t.0` / `t.1` against an N_TTUPLE local without pulling in strconv.
+fn fldnumidx(s: str) i32 = {
+	if (s.len == 0) { return -1; };
+	let r: i32 = 0;
+	let i: i32 = 0;
+	for (i < s.len) {
+		let b: u8 = s[i];
+		if (b < 48u8) { return -1; };
+		if (b > 57u8) { return -1; };
+		r = r * 10 + ((b - 48u8): i32);
+		i += 1;
+	};
+	return r;
+};
+
 fn primsize(name: str) i32 = {
 	if (streq(name, "u8"))   { return 1; };
 	if (streq(name, "i8"))   { return 1; };
@@ -672,7 +689,19 @@ fn slotsize(c: *cgen, typn: *node) i32 = {
 	if (k == N_TFN)    { return 8; };
 	if (k == N_TCHAN)  { return 8; };
 	if (k == N_TSLICE) { return 24; };
-	if (k == N_TTUPLE) { return 16; };
+	if (k == N_TTUPLE) {
+		// Sum element sizes. Mirrors C cgen which uses raw type
+		// sizes; padding to 8 happens inside slotsize for primitives,
+		// so a `(i64, str)` resolves to 8 + 16 = 24 (matches the C
+		// cgen 24B init / positional-access layout).
+		let total: i32 = 0;
+		let p: *node = typn.list;
+		for (p != nil) {
+			total += slotsize(c, p);
+			p = p.next;
+		};
+		return total;
+	};
 	if (k == N_TTAGGED){ return 24; };
 	if (k == N_TNAME) {
 		let nm: str = typn.str;