Decay an array to a pointer in the func param context

parse.c

@@ -380,9 +380,19 @@ static Type *func_params(Token **rest, Token *tok, Type *ty) {
   while (!equal(tok, ")")) {
     if (cur != &head)
       tok = skip(tok, ",");
-    Type *basety = declspec(&tok, tok, NULL);
-    Type *ty = declarator(&tok, tok, basety);
-    cur = cur->next = copy_type(ty);
+
+    Type *ty2 = declspec(&tok, tok, NULL);
+    ty2 = declarator(&tok, tok, ty2);
+
+    // "array of T" is converted to "pointer to T" only in the parameter
+    // context. For example, *argv[] is converted to **argv by this.
+    if (ty2->kind == TY_ARRAY) {
+      Token *name = ty2->name;
+      ty2 = pointer_to(ty2->base);
+      ty2->name = name;
+    }
+
+    cur = cur->next = copy_type(ty2);
   }
 
   ty = func_type(ty);

test/function.c

@@ -53,6 +53,8 @@ _Bool bool_fn_sub(_Bool x) { return x - 1; }
 
 static int static_fn() { return 3; }
 
+int param_decay(int x[]) { return x[0]; }
+
 int main() {
   ASSERT(3, ret3());
   ASSERT(8, add2(3, 5));
@@ -86,6 +88,8 @@ int main() {
 
   ASSERT(3, static_fn());
 
+  ASSERT(3, ({ int x[2]; x[0]=3; param_decay(x); }));
+
   printf("OK\n");
   return 0;
 }