From 537605a058f5041d751765123aad6d9404b87516 Mon Sep 17 00:00:00 2001
From: Felipe Pena <felipensp@gmail.com>
Date: Tue, 25 Feb 2025 11:42:23 -0300
Subject: [PATCH] checker: fix map when casting to interface (fix #23790)
 (#23799)

---
 vlib/v/gen/c/array.v                          | 40 +++++++++++++++----
 .../array_map_cast_interface_test.v           | 34 ++++++++++++++++
 2 files changed, 66 insertions(+), 8 deletions(-)
 create mode 100644 vlib/v/tests/builtin_arrays/array_map_cast_interface_test.v

diff --git a/vlib/v/gen/c/array.v b/vlib/v/gen/c/array.v
index 710306695..35997fada 100644
--- a/vlib/v/gen/c/array.v
+++ b/vlib/v/gen/c/array.v
@@ -560,7 +560,9 @@ fn (mut g Gen) gen_array_map(node ast.CallExpr) {
 	g.writeln('for (int ${i} = 0; ${i} < ${past.tmp_var}_len; ++${i}) {')
 	g.indent++
 	var_name := g.get_array_expr_param_name(mut expr)
-	g.write_prepared_var(var_name, inp_elem_type, inp_elem_styp, past.tmp_var, i, left_is_array)
+	is_auto_heap := expr is ast.CastExpr && (expr.expr is ast.Ident && expr.expr.is_auto_heap())
+	g.write_prepared_var(var_name, inp_elem_type, inp_elem_styp, past.tmp_var, i, left_is_array,
+		is_auto_heap)
 	g.set_current_pos_as_last_stmt_pos()
 	mut is_embed_map_filter := false
 	match mut expr {
@@ -976,7 +978,8 @@ fn (mut g Gen) gen_array_filter(node ast.CallExpr) {
 	i := g.new_tmp_var()
 	g.writeln('for (int ${i} = 0; ${i} < ${past.tmp_var}_len; ++${i}) {')
 	g.indent++
-	g.write_prepared_var(var_name, info.elem_type, elem_type_str, past.tmp_var, i, true)
+	g.write_prepared_var(var_name, info.elem_type, elem_type_str, past.tmp_var, i, true,
+		false)
 	g.set_current_pos_as_last_stmt_pos()
 	mut is_embed_map_filter := false
 	match mut expr {
@@ -1477,7 +1480,8 @@ fn (mut g Gen) gen_array_any(node ast.CallExpr) {
 	g.writeln('for (int ${i} = 0; ${i} < ${past.tmp_var}_len; ++${i}) {')
 	g.indent++
 
-	g.write_prepared_var(var_name, elem_type, elem_type_str, past.tmp_var, i, left_is_array)
+	g.write_prepared_var(var_name, elem_type, elem_type_str, past.tmp_var, i, left_is_array,
+		false)
 	g.set_current_pos_as_last_stmt_pos()
 	mut is_embed_map_filter := false
 	match mut expr {
@@ -1567,7 +1571,8 @@ fn (mut g Gen) gen_array_count(node ast.CallExpr) {
 	g.writeln('for (int ${i} = 0; ${i} < ${past.tmp_var}_len; ++${i}) {')
 	g.indent++
 
-	g.write_prepared_var(var_name, elem_type, elem_type_str, past.tmp_var, i, left_is_array)
+	g.write_prepared_var(var_name, elem_type, elem_type_str, past.tmp_var, i, left_is_array,
+		false)
 	g.set_current_pos_as_last_stmt_pos()
 	mut is_embed_map_filter := false
 	match mut expr {
@@ -1659,7 +1664,8 @@ fn (mut g Gen) gen_array_all(node ast.CallExpr) {
 
 	g.writeln('for (int ${i} = 0; ${i} < ${past.tmp_var}_len; ++${i}) {')
 	g.indent++
-	g.write_prepared_var(var_name, elem_type, elem_type_str, past.tmp_var, i, left_is_array)
+	g.write_prepared_var(var_name, elem_type, elem_type_str, past.tmp_var, i, left_is_array,
+		false)
 	g.empty_line = true
 	g.set_current_pos_as_last_stmt_pos()
 	mut is_embed_map_filter := false
@@ -1770,7 +1776,7 @@ fn (mut g Gen) write_prepared_tmp_value(tmp string, node &ast.CallExpr, tmp_styp
 }
 
 fn (mut g Gen) write_prepared_var(var_name string, elem_type ast.Type, inp_elem_type string, tmp string,
-	i string, is_array bool) {
+	i string, is_array bool, auto_heap bool) {
 	elem_sym := g.table.sym(elem_type)
 	if is_array {
 		if elem_sym.kind == .array_fixed {
@@ -1779,16 +1785,34 @@ fn (mut g Gen) write_prepared_var(var_name string, elem_type ast.Type, inp_elem_
 		} else if elem_sym.kind == .function {
 			g.writeln('voidptr ${var_name} = ((${inp_elem_type}*) ${tmp}_orig.data)[${i}];')
 		} else {
-			g.writeln('${inp_elem_type} ${var_name} = ((${inp_elem_type}*) ${tmp}_orig.data)[${i}];')
+			g.write('${inp_elem_type} ')
+			if auto_heap {
+				g.write('*')
+			}
+			g.write('${var_name} = ')
+			if auto_heap {
+				g.write('&')
+			}
+			g.writeln('((${inp_elem_type}*) ${tmp}_orig.data)[${i}];')
 		}
 	} else {
 		if elem_sym.kind == .array_fixed {
 			g.writeln('${inp_elem_type} ${var_name};')
 			g.writeln('memcpy(&${var_name}, &${tmp}_orig[${i}], sizeof(${inp_elem_type}));')
+		} else if auto_heap {
+			g.writeln('${inp_elem_type} *${var_name} = &${tmp}_orig[${i}];')
 		} else if elem_sym.kind == .function {
 			g.writeln('voidptr ${var_name} = (voidptr)${tmp}_orig[${i}];')
 		} else {
-			g.writeln('${inp_elem_type} ${var_name} = ${tmp}_orig[${i}];')
+			g.write('${inp_elem_type} ')
+			if auto_heap {
+				g.write('*')
+			}
+			g.write('${var_name} = ')
+			if auto_heap {
+				g.write('&')
+			}
+			g.writeln('${tmp}_orig[${i}];')
 		}
 	}
 }
diff --git a/vlib/v/tests/builtin_arrays/array_map_cast_interface_test.v b/vlib/v/tests/builtin_arrays/array_map_cast_interface_test.v
new file mode 100644
index 000000000..58798f19b
--- /dev/null
+++ b/vlib/v/tests/builtin_arrays/array_map_cast_interface_test.v
@@ -0,0 +1,34 @@
+interface Rect {
+	width  u32
+	height u32
+}
+
+struct Square {
+	side   u32
+	width  u32
+	height u32
+}
+
+fn test_main() {
+	squares := [Square{
+		side:   5
+		width:  5
+		height: 5
+	}]
+	rects := squares.map(Rect(it))
+
+	assert rects.str() == '[Rect(Square{
+    side: 5
+    width: 5
+    height: 5
+})]'
+}
+
+fn test_fixed_array() {
+	squares := [Square{
+		side:   5
+		width:  5
+		height: 5
+	}]!
+	rects := squares.map(Rect(it))
+}
-- 
2.39.5