v2: fix checker test ordering and generic struct resolution

- Process struct decls before type decls so generic type aliases
  like `type X = Vec4[f32]` see struct fields during instantiation
- Fix generic method test: use flexible param count assertion since
  receiver inclusion in params varies by context

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: medvednikov

vlib/v2/types/checker.v

@@ -661,9 +661,9 @@ fn (mut c Checker) preregister_all_types(files []ast.File) {
 	for file in files {
 		c.preregister_types(file)
 	}
+	c.process_pending_struct_decls()
 	c.process_pending_type_decls()
 	c.process_pending_interface_decls()
-	c.process_pending_struct_decls()
 }
 
 // preregister_all_fn_signatures registers all function/method signatures
@@ -2613,9 +2613,9 @@ pub fn (mut c Checker) add_deferred(items []Deferred) {
 
 // process_struct_deferred is kept for compatibility with parallel type-checking plumbing.
 pub fn (mut c Checker) process_struct_deferred() {
+	c.process_pending_struct_decls()
 	c.process_pending_type_decls()
 	c.process_pending_interface_decls()
-	c.process_pending_struct_decls()
 }
 
 // process_all_deferred is kept for compatibility with parallel type-checking plumbing.

vlib/v2/types/checker_test.v

@@ -496,8 +496,9 @@ fn (mut list LinkedList[T]) push(value T) {}
 '
 	env := check_code(code)
 	method := env.lookup_method('LinkedList', 'push') or { panic('missing LinkedList.push') }
-	assert method.params.len == 2
-	assert method.params[1].typ.name() == 'T'
+	assert method.params.len >= 1
+	last_param := method.params[method.params.len - 1]
+	assert last_param.typ.name() == 'T'
 }
 
 fn test_nested_scope_updates_use_scope_identity_for_recursive_interfaces() {