From 497d05f93e6fb011eb904e3fbccf1fa44532783c Mon Sep 17 00:00:00 2001
From: Alexander Medvednikov <alexander@medvednikov.com>
Date: Wed, 11 Mar 2026 15:39:50 +0300
Subject: [PATCH] checker: generics compile failure (fixes #24471)

---
 vlib/v/checker/checker.v                      | 12 ++---
 ...ime_if_generic_struct_init_selector_test.v | 47 +++++++++++++++++++
 2 files changed, 53 insertions(+), 6 deletions(-)
 create mode 100644 vlib/v/tests/comptime/comptime_if_generic_struct_init_selector_test.v

diff --git a/vlib/v/checker/checker.v b/vlib/v/checker/checker.v
index 6931a1aee..050c1c585 100644
--- a/vlib/v/checker/checker.v
+++ b/vlib/v/checker/checker.v
@@ -3488,12 +3488,6 @@ fn (mut c Checker) stmts_ending_with_expression(mut stmts []ast.Stmt, expected_o
 
 fn (mut c Checker) unwrap_generic(typ ast.Type) ast.Type {
 	if typ.has_flag(.generic) {
-		if c.inside_generic_struct_init {
-			generic_names := c.cur_struct_generic_types.map(c.table.sym(it).name)
-			if t_typ := c.table.convert_generic_type(typ, generic_names, c.cur_struct_concrete_types) {
-				return t_typ
-			}
-		}
 		if c.table.cur_fn != unsafe { nil } {
 			if t_typ := c.table.convert_generic_type(typ, c.table.cur_fn.generic_names,
 				c.table.cur_concrete_types)
@@ -3508,6 +3502,12 @@ fn (mut c Checker) unwrap_generic(typ ast.Type) ast.Type {
 				}
 			}
 		}
+		if c.inside_generic_struct_init {
+			generic_names := c.cur_struct_generic_types.map(c.table.sym(it).name)
+			if t_typ := c.table.convert_generic_type(typ, generic_names, c.cur_struct_concrete_types) {
+				return t_typ
+			}
+		}
 	}
 	return typ
 }
diff --git a/vlib/v/tests/comptime/comptime_if_generic_struct_init_selector_test.v b/vlib/v/tests/comptime/comptime_if_generic_struct_init_selector_test.v
new file mode 100644
index 000000000..f99f5780e
--- /dev/null
+++ b/vlib/v/tests/comptime/comptime_if_generic_struct_init_selector_test.v
@@ -0,0 +1,47 @@
+struct CtType1 {
+	item f32
+}
+
+struct CtType2 {
+	item int
+}
+
+struct CtGenericThing[T] {
+	part1 T
+	part2 T
+}
+
+struct CtAnotherGenericThing[T] {
+	part3 T
+}
+
+fn (thing CtGenericThing[T]) inline_weird() CtAnotherGenericThing[int] {
+	$if T is CtType2 {
+		return CtAnotherGenericThing[int]{thing.part1.item + thing.part2.item}
+	} $else $if T is CtType1 {
+		return CtAnotherGenericThing[int]{int(thing.part1.item + thing.part2.item)}
+	} $else {
+		$compile_error('unrecognised type')
+	}
+}
+
+fn (thing CtGenericThing[T]) temp_var_weird() CtAnotherGenericThing[int] {
+	result := thing.part1.item + thing.part2.item
+	$if T is CtType2 {
+		return CtAnotherGenericThing[int]{result}
+	} $else $if T is CtType1 {
+		return CtAnotherGenericThing[int]{int(result)}
+	} $else {
+		$compile_error('unrecognised type')
+	}
+}
+
+fn test_comptime_if_generic_struct_init_selector() {
+	thing1 := CtGenericThing{CtType1{1}, CtType1{2}}
+	assert thing1.inline_weird().part3 == 3
+	assert thing1.temp_var_weird().part3 == 3
+
+	thing2 := CtGenericThing{CtType2{1}, CtType2{2}}
+	assert thing2.inline_weird().part3 == 3
+	assert thing2.temp_var_weird().part3 == 3
+}
-- 
2.39.5