From 9c4dfd3848089a2a003a2391ea4a78367c941d0f Mon Sep 17 00:00:00 2001
From: Felipe Pena <felipensp@gmail.com>
Date: Mon, 22 Sep 2025 05:31:29 -0300
Subject: [PATCH] cgen: fix option unwrap with string interpolation (fix
 #25337) (#25367)

---
 vlib/v/gen/c/str_intp.v                       |  3 +++
 vlib/v/markused/walker.v                      |  3 +++
 .../v/tests/options/option_unwrap_none_test.v | 19 +++++++++++++++++++
 3 files changed, 25 insertions(+)
 create mode 100644 vlib/v/tests/options/option_unwrap_none_test.v

diff --git a/vlib/v/gen/c/str_intp.v b/vlib/v/gen/c/str_intp.v
index 609b5b9f4..4dfaa70a4 100644
--- a/vlib/v/gen/c/str_intp.v
+++ b/vlib/v/gen/c/str_intp.v
@@ -225,6 +225,9 @@ fn (mut g Gen) str_val(node ast.StringInterLiteral, i int, fmts []u8) {
 					if cast_sym.info is ast.Aggregate {
 						exp_typ = cast_sym.info.types[g.aggregate_type_idx]
 					}
+					if exp_typ.has_flag(.option) && expr.obj.is_unwrapped {
+						exp_typ = exp_typ.clear_flag(.option)
+					}
 				}
 			}
 		}
diff --git a/vlib/v/markused/walker.v b/vlib/v/markused/walker.v
index 6b7bfc48f..f45adbef9 100644
--- a/vlib/v/markused/walker.v
+++ b/vlib/v/markused/walker.v
@@ -716,6 +716,9 @@ fn (mut w Walker) expr(node_ ast.Expr) {
 					}
 				}
 			}
+			if node.obj is ast.Var && node.obj.is_unwrapped {
+				w.used_option++
+			}
 			w.or_block(node.or_expr)
 		}
 		ast.LambdaExpr {
diff --git a/vlib/v/tests/options/option_unwrap_none_test.v b/vlib/v/tests/options/option_unwrap_none_test.v
new file mode 100644
index 000000000..fca85a62c
--- /dev/null
+++ b/vlib/v/tests/options/option_unwrap_none_test.v
@@ -0,0 +1,19 @@
+fn fake_prompt[T](msg string, default ?T) string {
+	return build_prompt(msg, default)
+}
+
+fn build_prompt[T](msg string, default ?T) string {
+	mut s := msg
+	if default != none {
+		s += ' [${default}]'
+	}
+	s += ': '
+	return s
+}
+
+fn test_main() {
+	p1 := fake_prompt[string]('hello', none)
+	p2 := fake_prompt[string]('hello', 'world')
+	assert p1 == 'hello: '
+	assert p2 == 'hello [world]: '
+}
-- 
2.39.5