From c9ecc5b0ddd6258f9aa35b23f07b98c4112df49b Mon Sep 17 00:00:00 2001
From: Felipe Pena <felipensp@gmail.com>
Date: Sun, 10 Nov 2024 15:15:01 -0300
Subject: [PATCH] v: add `typeof(expr).unaliased_typ` (#22806)

---
 vlib/v/checker/checker.v                 |  2 +-
 vlib/v/gen/c/cgen.v                      |  8 ++++++++
 vlib/v/tests/typeof_unaliased_typ_test.v | 20 ++++++++++++++++++++
 3 files changed, 29 insertions(+), 1 deletion(-)
 create mode 100644 vlib/v/tests/typeof_unaliased_typ_test.v

diff --git a/vlib/v/checker/checker.v b/vlib/v/checker/checker.v
index 573628446a..4d935fca58 100644
--- a/vlib/v/checker/checker.v
+++ b/vlib/v/checker/checker.v
@@ -1537,7 +1537,7 @@ fn (mut c Checker) selector_expr(mut node ast.SelectorExpr) ast.Type {
 			else {
 				if node.field_name == 'name' {
 					return ast.string_type
-				} else if node.field_name == 'idx' {
+				} else if node.field_name in ['idx', 'unaliased_typ'] {
 					return ast.int_type
 				} else if node.field_name == 'indirections' {
 					return ast.int_type
diff --git a/vlib/v/gen/c/cgen.v b/vlib/v/gen/c/cgen.v
index 05d7b0c8b7..59a50eb67c 100644
--- a/vlib/v/gen/c/cgen.v
+++ b/vlib/v/gen/c/cgen.v
@@ -3897,6 +3897,14 @@ fn (mut g Gen) selector_expr(node ast.SelectorExpr) {
 					// `typeof(expr).idx`
 					g.write(int(g.unwrap_generic(name_type)).str())
 					return
+				} else if node.field_name == 'unaliased_typ' {
+					mut name_type := node.name_type
+					if node.expr is ast.TypeOf {
+						name_type = g.resolve_comptime_type(node.expr.expr, name_type)
+					}
+					// `typeof(expr).unaliased_typ`
+					g.write(int(g.table.unaliased_type(g.unwrap_generic(name_type))).str())
+					return
 				} else if node.field_name == 'indirections' {
 					mut name_type := node.name_type
 					if node.expr is ast.TypeOf {
diff --git a/vlib/v/tests/typeof_unaliased_typ_test.v b/vlib/v/tests/typeof_unaliased_typ_test.v
new file mode 100644
index 0000000000..b964dd30b8
--- /dev/null
+++ b/vlib/v/tests/typeof_unaliased_typ_test.v
@@ -0,0 +1,20 @@
+struct Foo {
+	a int
+}
+
+type Bar = Foo
+
+type ArrBar = []Bar
+
+fn test_main() {
+	assert typeof[Bar]().unaliased_typ == typeof[Foo]().unaliased_typ
+	assert typeof[int]().unaliased_typ != typeof[Foo]().unaliased_typ
+	assert typeof[int]().unaliased_typ == typeof[int]().unaliased_typ
+	assert typeof[ArrBar]().unaliased_typ == typeof[[]Bar]().idx
+
+	a := Bar{}
+	assert typeof(a).unaliased_typ == typeof[Foo]().idx
+
+	b := ArrBar{}
+	assert typeof(b).unaliased_typ == typeof[[]Bar]().idx
+}