From ffa9faced0348650330154da522fd95beeae9a17 Mon Sep 17 00:00:00 2001
From: Alexander Medvednikov <alexander@medvednikov.com>
Date: Tue, 21 Apr 2026 05:21:37 +0300
Subject: [PATCH] cgen: fix optional val return in map got wrong value (fixes
 #26239)

---
 vlib/v/gen/c/index.v                            | 17 ++++++++++++++++-
 .../map_value_with_option_result_test.v         | 12 ++++++++++++
 2 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/vlib/v/gen/c/index.v b/vlib/v/gen/c/index.v
index 720d64dc4..a8dbabe3d 100644
--- a/vlib/v/gen/c/index.v
+++ b/vlib/v/gen/c/index.v
@@ -802,6 +802,17 @@ fn (mut g Gen) index_of_map(node ast.IndexExpr, sym ast.TypeSymbol) {
 				}
 			}
 			if val_type.has_flag(.option) {
+				or_value_type := g.resolved_or_block_value_type(node.or_expr)
+				keep_option_result := node.is_option || (node.or_expr.kind == .block
+					&& (or_value_type in [ast.none_type, ast.none_type_idx]
+					|| or_value_type.has_flag(.option)))
+				plain_val_type := val_type.clear_option_and_result()
+				plain_val_sym := g.table.final_sym(plain_val_type)
+				plain_val_type_str := if plain_val_sym.kind == .function {
+					'voidptr'
+				} else {
+					g.styp(plain_val_type)
+				}
 				g.writeln('${val_type_str} ${tmp_opt} = {0};')
 				g.writeln('if (${tmp_opt_ptr}) {')
 				g.writeln('\t${tmp_opt} = *${tmp_opt_ptr};')
@@ -814,7 +825,11 @@ fn (mut g Gen) index_of_map(node ast.IndexExpr, sym ast.TypeSymbol) {
 				if is_gen_or_and_assign_rhs {
 					g.set_current_pos_as_last_stmt_pos()
 				}
-				g.write('\n${cur_line}${tmp_opt}')
+				if keep_option_result {
+					g.write('\n${cur_line}${tmp_opt}')
+				} else {
+					g.write('\n${cur_line}(*(${plain_val_type_str}*)${tmp_opt}.data)')
+				}
 			} else {
 				opt_val_type := g.styp(val_type.set_flag(.option))
 				g.writeln('${opt_val_type} ${tmp_opt} = {0};')
diff --git a/vlib/v/tests/builtin_maps/map_value_with_option_result_test.v b/vlib/v/tests/builtin_maps/map_value_with_option_result_test.v
index 040da247e..b6c163908 100644
--- a/vlib/v/tests/builtin_maps/map_value_with_option_result_test.v
+++ b/vlib/v/tests/builtin_maps/map_value_with_option_result_test.v
@@ -32,3 +32,15 @@ fn test_map_value_with_option_or_block() {
 	assert value == none
 	assert m['missing'] or { none } == none
 }
+
+fn test_map_value_with_option_or_block_value_fallback() {
+	mut m := map[string]?string{}
+	m['present'] = ?string('xyz')
+	m['none'] = ?string(none)
+	missing := m['missing'] or { 'abc' }
+	present := m['present'] or { 'abc' }
+	none_value := m['none'] or { 'abc' }
+	assert missing == 'abc'
+	assert present == 'xyz'
+	assert none_value == 'abc'
+}
-- 
2.39.5