wcc: Hare-style struct embedding (anon + bare-name)

Struct members can be `struct { ... }` (anonymous nested) or a bare
named type, in addition to `name: type`. The inner struct's fields
are promoted to the outer scope with offsets shifted by the embed
base; codegen already keys off Tfield.offset so cgen needs no change.
Errors on non-struct embed or name collision.

cmd/wcc/parse.c

@@ -191,9 +191,21 @@ parsetype(Parser *p)
 		while (p->cur.kind != TK_RBRACE && p->cur.kind != TK_EOF) {
 			Pos fp = p->cur.pos;
 			Node *f = newnode(p->a, N_TFIELD, fp);
-			f->str = expectident(p);
-			expect(p, TK_COLON);
-			f->lhs = parsetype(p);
+			/* Three member forms:
+			 *   name: type       — regular field
+			 *   struct { ... }   — anonymous embedded struct
+			 *   Identifier       — bare-name embedded type
+			 * Embeds carry f->str == NULL and the type in f->lhs. */
+			if (p->cur.kind == TK_STRUCT) {
+				f->lhs = parsetype(p);
+			} else if (p->cur.kind == TK_IDENT
+			    && peek(p).kind != TK_COLON) {
+				f->lhs = parsetype(p);
+			} else {
+				f->str = expectident(p);
+				expect(p, TK_COLON);
+				f->lhs = parsetype(p);
+			}
 			if (head == NULL) head = f;
 			else tail->next = f;
 			tail = f;