From 6df25afe0615c430e0e1ffc99fe11c8a27252d57 Mon Sep 17 00:00:00 2001
From: Felipe Pena <felipensp@gmail.com>
Date: Sat, 7 Dec 2024 23:03:38 -0300
Subject: [PATCH] cgen: fix option codegen for accept IError value (fix #23076)
 (#23085)

---
 vlib/v/checker/check_types.v                  |  2 ++
 vlib/v/gen/c/cgen.v                           |  2 ++
 vlib/v/tests/options/option_with_error_test.v | 17 +++++++++++++++++
 3 files changed, 21 insertions(+)
 create mode 100644 vlib/v/tests/options/option_with_error_test.v

diff --git a/vlib/v/checker/check_types.v b/vlib/v/checker/check_types.v
index f0f827ab2..c5523d501 100644
--- a/vlib/v/checker/check_types.v
+++ b/vlib/v/checker/check_types.v
@@ -162,6 +162,8 @@ fn (mut c Checker) check_types(got ast.Type, expected ast.Type) bool {
 	}
 	if expected.has_option_or_result() {
 		sym := c.table.sym(got)
+		// Allow error() for Option and Result types
+		// `none` for Option only
 		if ((sym.idx == ast.error_type_idx || got in [ast.none_type, ast.error_type])
 			&& expected.has_flag(.option))
 			|| ((sym.idx == ast.error_type_idx || got == ast.error_type)
diff --git a/vlib/v/gen/c/cgen.v b/vlib/v/gen/c/cgen.v
index 1aabb8b0c..fc3d9485f 100644
--- a/vlib/v/gen/c/cgen.v
+++ b/vlib/v/gen/c/cgen.v
@@ -2079,6 +2079,8 @@ fn (mut g Gen) expr_with_tmp_var(expr ast.Expr, expr_typ ast.Type, ret_typ ast.T
 		g.write('${g.styp(ret_typ)} ${tmp_var} = ')
 		g.gen_option_error(ret_typ, expr)
 		g.writeln(';')
+	} else if expr is ast.Ident && expr_typ == ast.error_type {
+		g.writeln('${g.styp(ret_typ)} ${tmp_var} = {.state=2, .err = ${expr.name}};')
 	} else {
 		mut simple_assign := false
 		if ret_typ.has_flag(.generic) {
diff --git a/vlib/v/tests/options/option_with_error_test.v b/vlib/v/tests/options/option_with_error_test.v
new file mode 100644
index 000000000..c8d216b8f
--- /dev/null
+++ b/vlib/v/tests/options/option_with_error_test.v
@@ -0,0 +1,17 @@
+struct Struct {
+	error ?string
+}
+
+fn result_function() !Struct {
+	return error('This is an error')
+}
+
+fn test_main() {
+	some_struct := result_function() or {
+		Struct{
+			error: err
+		}
+	}
+	// some_struct.error?
+	assert some_struct.error or { '${err}' } == 'This is an error'
+}
-- 
2.39.5