From 599ae8087aaa3dccf495aaea23e9bf2238de6c55 Mon Sep 17 00:00:00 2001
From: Alexander Medvednikov <alexander@medvednikov.com>
Date: Wed, 15 Apr 2026 05:13:43 +0300
Subject: [PATCH] checker: fix enum taking function as init value when cast to
 int (fixes #25908)

---
 vlib/v/checker/checker.v                        | 17 +++++++++++++++++
 .../tests/enum_non_comptime_cast_call_err.out   |  7 +++++++
 .../tests/enum_non_comptime_cast_call_err.vv    |  9 +++++++++
 .../enums/enum_with_comptime_fn_calls_test.v    | 12 ++++++++++++
 4 files changed, 45 insertions(+)
 create mode 100644 vlib/v/checker/tests/enum_non_comptime_cast_call_err.out
 create mode 100644 vlib/v/checker/tests/enum_non_comptime_cast_call_err.vv

diff --git a/vlib/v/checker/checker.v b/vlib/v/checker/checker.v
index aa6808a02..66c0e3772 100644
--- a/vlib/v/checker/checker.v
+++ b/vlib/v/checker/checker.v
@@ -3359,9 +3359,26 @@ fn (mut c Checker) enum_decl(mut node ast.EnumDecl) {
 							if field.expr.expr.val !in seen_enum_field_names {
 								c.error('`${field.expr.expr.enum_name}.${field.expr.expr.val}` should be declared before using it',
 									field.expr.pos)
+								continue
 							}
 						}
 					}
+					cast_expr := ast.Expr(field.expr)
+					if comptime_value := c.eval_comptime_const_expr(cast_expr, 0) {
+						comptime_lit := c.comptime_value_to_integer_literal(comptime_value,
+							field.expr.pos) or {
+							c.error('the default value for an enum has to be an integer',
+								field.expr.pos)
+							continue
+						}
+						c.check_enum_field_integer_literal(comptime_lit, signed,
+							node.is_multi_allowed, senum_type, field.expr.pos, mut useen,
+							enum_umin, enum_umax, mut iseen, enum_imin, enum_imax)
+						field.expr = comptime_lit
+					} else {
+						c.error('the default value for an enum has to be an integer',
+							field.expr.pos)
+					}
 				}
 				ast.CallExpr, ast.IfExpr {
 					call_ret_type := c.expr(mut field.expr)
diff --git a/vlib/v/checker/tests/enum_non_comptime_cast_call_err.out b/vlib/v/checker/tests/enum_non_comptime_cast_call_err.out
new file mode 100644
index 000000000..990637394
--- /dev/null
+++ b/vlib/v/checker/tests/enum_non_comptime_cast_call_err.out
@@ -0,0 +1,7 @@
+vlib/v/checker/tests/enum_non_comptime_cast_call_err.vv:6:8: error: the default value for an enum has to be an integer
+    4 | 
+    5 | enum Color {
+    6 |     red = int(get_value(1, 2, 3, 4))
+      |           ~~~~~~~~~~~~~~~~~~~~~~~~~~
+    7 | }
+    8 |
diff --git a/vlib/v/checker/tests/enum_non_comptime_cast_call_err.vv b/vlib/v/checker/tests/enum_non_comptime_cast_call_err.vv
new file mode 100644
index 000000000..23680d95b
--- /dev/null
+++ b/vlib/v/checker/tests/enum_non_comptime_cast_call_err.vv
@@ -0,0 +1,9 @@
+fn get_value(a u8, b u8, c u8, d u8) u32 {
+	return (u32(a) << 24) | (u32(b) << 16) | (u32(c) << 8) | u32(d)
+}
+
+enum Color {
+	red = int(get_value(1, 2, 3, 4))
+}
+
+fn main() {}
diff --git a/vlib/v/tests/enums/enum_with_comptime_fn_calls_test.v b/vlib/v/tests/enums/enum_with_comptime_fn_calls_test.v
index e015673b6..490f496f2 100644
--- a/vlib/v/tests/enums/enum_with_comptime_fn_calls_test.v
+++ b/vlib/v/tests/enums/enum_with_comptime_fn_calls_test.v
@@ -9,8 +9,20 @@ enum Colors as u32 {
 	blue  = pack_color(0, 0, 255, 255)
 }
 
+enum CastedColors {
+	red   = int(pack_color(1, 2, 3, 4))
+	green = int(pack_color(5, 6, 7, 8))
+	blue  = int(pack_color(9, 10, 11, 12))
+}
+
 fn test_enum_values_from_comptime_function_calls() {
 	assert u32(Colors.red) == u32(0xff0000ff)
 	assert u32(Colors.green) == u32(0x00ff00ff)
 	assert u32(Colors.blue) == u32(0x0000ffff)
 }
+
+fn test_enum_values_from_casted_comptime_function_calls() {
+	assert int(CastedColors.red) == 0x01020304
+	assert int(CastedColors.green) == 0x05060708
+	assert int(CastedColors.blue) == 0x090a0b0c
+}
-- 
2.39.5