From 0390a7a988664cd0b8e88d859dda0ec0c6903820 Mon Sep 17 00:00:00 2001
From: yuyi <yuyi98@163.com>
Date: Mon, 31 Oct 2022 02:26:33 +0800
Subject: [PATCH] cgen: fix return match expr of sumtype result (#16264)

---
 vlib/v/gen/c/cgen.v                           |  8 ++++--
 ...return_match_expr_of_sumtype_result_test.v | 25 +++++++++++++++++++
 2 files changed, 31 insertions(+), 2 deletions(-)
 create mode 100644 vlib/v/tests/return_match_expr_of_sumtype_result_test.v

diff --git a/vlib/v/gen/c/cgen.v b/vlib/v/gen/c/cgen.v
index 8b94fdb91b..762b3623b9 100644
--- a/vlib/v/gen/c/cgen.v
+++ b/vlib/v/gen/c/cgen.v
@@ -1666,8 +1666,10 @@ fn (mut g Gen) stmts_with_tmp_var(stmts []ast.Stmt, tmp_var string) bool {
 							g.expr(stmt.expr)
 							g.writeln(';')
 						} else {
+							ret_typ := g.fn_decl.return_type.clear_flag(.optional)
+							styp = g.base_type(ret_typ)
 							g.write('_option_ok(&($styp[]) { ')
-							g.expr(stmt.expr)
+							g.expr_with_cast(stmt.expr, stmt.typ, ret_typ)
 							g.writeln(' }, ($c.option_name*)(&$tmp_var), sizeof($styp));')
 						}
 					}
@@ -1696,8 +1698,10 @@ fn (mut g Gen) stmts_with_tmp_var(stmts []ast.Stmt, tmp_var string) bool {
 							g.expr(stmt.expr)
 							g.writeln(';')
 						} else {
+							ret_typ := g.fn_decl.return_type.clear_flag(.result)
+							styp = g.base_type(ret_typ)
 							g.write('_result_ok(&($styp[]) { ')
-							g.expr(stmt.expr)
+							g.expr_with_cast(stmt.expr, stmt.typ, ret_typ)
 							g.writeln(' }, ($c.result_name*)(&$tmp_var), sizeof($styp));')
 						}
 					}
diff --git a/vlib/v/tests/return_match_expr_of_sumtype_result_test.v b/vlib/v/tests/return_match_expr_of_sumtype_result_test.v
new file mode 100644
index 0000000000..dfa33e98c3
--- /dev/null
+++ b/vlib/v/tests/return_match_expr_of_sumtype_result_test.v
@@ -0,0 +1,25 @@
+type Foo = int | string
+
+fn foo1() !Foo {
+	return match true {
+		true { 1 }
+		else { '' }
+	}
+}
+
+fn foo2() ?Foo {
+	return match true {
+		true { 1 }
+		else { '' }
+	}
+}
+
+fn test_return_match_expr_of_sumtype_opt_res() {
+	ret1 := foo1() or { return }
+	println(ret1)
+	assert '$ret1' == 'Foo(1)'
+
+	ret2 := foo2() or { return }
+	println(ret2)
+	assert '$ret2' == 'Foo(1)'
+}