From 697cfa701fd8788ea202ceaaa3c6c0e7120e7807 Mon Sep 17 00:00:00 2001
From: Delyan Angelov <delian66@gmail.com>
Date: Thu, 14 Aug 2025 17:11:53 +0300
Subject: [PATCH] ast: allow using aliased types in interface method
 implementations (provide backwards compatibility to `ui`, during the
 migration of code from `gx` to `gg`) (#25106)

---
 vlib/v/ast/table.v                            |  3 +-
 vlib/v/pref/pref.v                            |  2 +-
 ...mplemented_with_type_aliased_params_test.v | 52 +++++++++++++++++++
 3 files changed, 55 insertions(+), 2 deletions(-)
 create mode 100644 vlib/v/tests/interfaces/interface_method_with_params_implemented_with_type_aliased_params_test.v

diff --git a/vlib/v/ast/table.v b/vlib/v/ast/table.v
index 9ec37ca58..05bf379a6 100644
--- a/vlib/v/ast/table.v
+++ b/vlib/v/ast/table.v
@@ -218,7 +218,8 @@ pub fn (t &Table) is_same_method(f &Fn, func &Fn) string {
 
 	for i in 0 .. f.params.len {
 		// don't check receiver for `.typ`
-		has_unexpected_type := i > 0 && f.params[i].typ != func.params[i].typ
+		has_unexpected_type := i > 0
+			&& t.unaliased_type(f.params[i].typ) != t.unaliased_type(func.params[i].typ)
 		// temporary hack for JS ifaces
 		lsym := t.sym(f.params[i].typ)
 		rsym := t.sym(func.params[i].typ)
diff --git a/vlib/v/pref/pref.v b/vlib/v/pref/pref.v
index 1d2dbd938..83320e4a4 100644
--- a/vlib/v/pref/pref.v
+++ b/vlib/v/pref/pref.v
@@ -239,7 +239,7 @@ pub mut:
 	cache_manager       vcache.CacheManager
 	gc_mode             GarbageCollectionMode = .unknown // .no_gc, .boehm, .boehm_leak, ...
 	assert_failure_mode AssertFailureMode // whether to call abort() or print_backtrace() after an assertion failure
-	message_limit       int = 150 // the maximum amount of warnings/errors/notices that will be accumulated
+	message_limit       int = 200 // the maximum amount of warnings/errors/notices that will be accumulated
 	nofloat             bool // for low level code, like kernels: replaces f32 with u32 and f64 with u64
 	use_coroutines      bool // experimental coroutines
 	fast_math           bool // -fast-math will pass either -ffast-math or /fp:fast (for msvc) to the C backend
diff --git a/vlib/v/tests/interfaces/interface_method_with_params_implemented_with_type_aliased_params_test.v b/vlib/v/tests/interfaces/interface_method_with_params_implemented_with_type_aliased_params_test.v
new file mode 100644
index 000000000..8cca66307
--- /dev/null
+++ b/vlib/v/tests/interfaces/interface_method_with_params_implemented_with_type_aliased_params_test.v
@@ -0,0 +1,52 @@
+// This tests, whether type aliased values, can be used in place of their non aliased versions,
+// when implementing interfaces. This is important for allowing type aliases in one module,
+// to be used as substitutes to keep backwards compatibility, when migrating functionality
+// from one module to another, which was the case, when deprecating `gx` in favor of moving
+// its functionality into `gg`, while still keeping old code using `gx` compilable for a while,
+// by making `gx` import `gg` and declare a few shallow type aliases to the new `gg` types,
+// so that older `gx` importers and their CIs (like the `ui` module), can continue to work
+// (with just deprecation notices), without forcing an immediate change.
+struct Param1 {
+	x int
+}
+
+struct Param2 {
+	y f32
+}
+
+type AliasParam1 = Param1
+type AliasParam2 = Param2
+
+interface MyInterface {
+	method1(p1 Param1, p2 Param2) f32
+}
+
+struct ImplDirect {
+	v int
+}
+
+fn (i ImplDirect) method1(p1 Param1, p2 Param2) f32 {
+	println(i)
+	println(p1)
+	println(p2)
+	return i.v + p1.x + p2.y
+}
+
+struct ImplWithAliasedParams {
+	v int
+}
+
+fn (i ImplWithAliasedParams) method1(p1 AliasParam1, p2 AliasParam2) f32 {
+	println(i)
+	println(p1)
+	println(p2)
+	return i.v + p1.x + p2.y
+}
+
+fn test_interface_method_can_be_called_with_aliased_type_values() {
+	isdirect := MyInterface(ImplDirect{1000})
+	isalias := MyInterface(ImplWithAliasedParams{2000})
+
+	assert isdirect.method1(AliasParam1{123}, AliasParam2{1.1}) == 1124.1
+	assert isalias.method1(AliasParam1{456}, AliasParam2{2.2}) == 2458.2
+}
-- 
2.39.5