From 877149b8e0150c88645d260ba500a607f4013e87 Mon Sep 17 00:00:00 2001
From: Alexander Medvednikov <alexander@medvednikov.com>
Date: Thu, 26 Mar 2026 00:09:58 +0300
Subject: [PATCH] cgen: fix error for value := &(m[key]) with map values (fixes
 #15115)

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

diff --git a/vlib/v/gen/c/index.v b/vlib/v/gen/c/index.v
index 9a94a7514..a6f688f9d 100644
--- a/vlib/v/gen/c/index.v
+++ b/vlib/v/gen/c/index.v
@@ -574,6 +574,12 @@ fn (mut g Gen) index_of_map(node ast.IndexExpr, sym ast.TypeSymbol) {
 		}
 		if gen_or {
 			g.writeln(';')
+			// The surrounding expression may already carry a pointer prefix placeholder.
+			direct_ptr_cur_line := if cur_line.ends_with('&') || cur_line.ends_with('H') {
+				cur_line[..cur_line.len - 1]
+			} else {
+				cur_line
+			}
 			if g.unsafe_level > 0 && !node.is_option && !node.is_setter
 				&& node.or_expr.kind == .block && node.or_expr.stmts.len == 1 {
 				last_stmt := node.or_expr.stmts[0]
@@ -582,7 +588,11 @@ fn (mut g Gen) index_of_map(node ast.IndexExpr, sym ast.TypeSymbol) {
 					g.write('if (!${tmp_opt_ptr}) { ${tmp_opt_ptr} = ')
 					g.expr(last_stmt.expr)
 					g.write('; }')
-					g.write('\n${cur_line}(*${tmp_opt_ptr})')
+					if cur_line.ends_with('&') || cur_line.ends_with('H') {
+						g.write('\n${direct_ptr_cur_line}${tmp_opt_ptr}')
+					} else {
+						g.write('\n${cur_line}(*${tmp_opt_ptr})')
+					}
 					return
 				}
 			}
diff --git a/vlib/v/tests/builtin_maps/unsafe_pointers_to_map_values_test.v b/vlib/v/tests/builtin_maps/unsafe_pointers_to_map_values_test.v
index d5df26101..9d38870c9 100644
--- a/vlib/v/tests/builtin_maps/unsafe_pointers_to_map_values_test.v
+++ b/vlib/v/tests/builtin_maps/unsafe_pointers_to_map_values_test.v
@@ -9,6 +9,11 @@ mut:
 	mymap map[string]MyObject
 }
 
+struct ArrayDefaultObject {
+mut:
+	xs []u8 = []u8{len: 12, init: 0}
+}
+
 fn test_codegen_for_unsafe_pointers_to_map_values() {
 	mut inst := Abc{}
 	inst.mymap['abc'] = MyObject{123, 'abc'}
@@ -39,3 +44,15 @@ fn test_codegen_for_unsafe_pointers_to_map_values() {
 	assert inst.mymap['abc'].x == 999
 	assert inst.mymap['abc'].s == 'xyz'
 }
+
+fn test_codegen_for_unsafe_pointers_to_map_values_with_array_defaults() {
+	mut values := map[string]ArrayDefaultObject{}
+	mut missing := unsafe { &values['missing'] or { nil } }
+	assert missing == unsafe { nil }
+	values['abc'] = ArrayDefaultObject{}
+	mut value := unsafe { &values['abc'] or { nil } }
+	assert value != unsafe { nil }
+	assert value.xs.len == 12
+	value.xs[0] = 7
+	assert values['abc'].xs[0] == 7
+}
-- 
2.39.5