Handle struct designator for anonymous struct member

parse.c

@@ -149,6 +149,7 @@ static Node *new_add(Node *lhs, Node *rhs, Token *tok);
 static Node *new_sub(Node *lhs, Node *rhs, Token *tok);
 static Node *mul(Token **rest, Token *tok);
 static Node *cast(Token **rest, Token *tok);
+static Member *get_struct_member(Type *ty, Token *tok);
 static Type *struct_decl(Token **rest, Token *tok);
 static Type *union_decl(Token **rest, Token *tok);
 static Node *postfix(Token **rest, Token *tok);
@@ -888,11 +889,22 @@ static int array_designator(Token **rest, Token *tok, Type *ty) {
 
 // struct-designator = "." ident
 static Member *struct_designator(Token **rest, Token *tok, Type *ty) {
+  Token *start = tok;
   tok = skip(tok, ".");
   if (tok->kind != TK_IDENT)
     error_tok(tok, "expected a field designator");
 
   for (Member *mem = ty->members; mem; mem = mem->next) {
+    // Anonymous struct member
+    if (mem->ty->kind == TY_STRUCT && !mem->name) {
+      if (get_struct_member(mem->ty, tok)) {
+        *rest = start;
+        return mem;
+      }
+      continue;
+    }
+
+    // Regular struct member
     if (mem->name->len == tok->len && !strncmp(mem->name->loc, tok->loc, tok->len)) {
       *rest = tok->next;
       return mem;

test/initializer.c

@@ -255,6 +255,10 @@ int main() {
   ASSERT(0, g51[0].a);
   ASSERT(0, g51[1].a);
 
+  ASSERT(1, ({ struct { struct { int a; struct { int b; }; }; int c; } x={1,2,3,.b=4,5}; x.a; }));
+  ASSERT(4, ({ struct { struct { int a; struct { int b; }; }; int c; } x={1,2,3,.b=4,5}; x.b; }));
+  ASSERT(5, ({ struct { struct { int a; struct { int b; }; }; int c; } x={1,2,3,.b=4,5}; x.c; }));
+
   printf("OK\n");
   return 0;
 }