From 752e4c2e4782e6feeaa9cff1f65414daab01cfdd Mon Sep 17 00:00:00 2001
From: Felipe Pena <felipensp@gmail.com>
Date: Sat, 24 Jun 2023 14:54:49 -0300
Subject: [PATCH] cgen, checker: allow `a << none`, where `a` is `[]?&int`
 (#18539)

---
 vlib/v/checker/infix.v                 |  3 +++
 vlib/v/gen/c/auto_str_methods.v        | 16 ++++++++++++----
 vlib/v/gen/c/infix.v                   |  2 +-
 vlib/v/tests/option_assign_none_test.v | 11 +++++++++++
 4 files changed, 27 insertions(+), 5 deletions(-)
 create mode 100644 vlib/v/tests/option_assign_none_test.v

diff --git a/vlib/v/checker/infix.v b/vlib/v/checker/infix.v
index d8e6dad130..a1e05ac112 100644
--- a/vlib/v/checker/infix.v
+++ b/vlib/v/checker/infix.v
@@ -522,6 +522,9 @@ fn (mut c Checker) infix_expr(mut node ast.InfixExpr) ast.Type {
 				} else if c.check_types(unwrapped_right_type, c.unwrap_generic(left_type)) {
 					return ast.void_type
 				}
+				if left_value_type.has_flag(.option) && right_type == ast.none_type {
+					return ast.void_type
+				}
 				c.error('cannot append `${right_sym.name}` to `${left_sym.name}`', right_pos)
 				return ast.void_type
 			} else {
diff --git a/vlib/v/gen/c/auto_str_methods.v b/vlib/v/gen/c/auto_str_methods.v
index 4c176d9dba..6eb43438a5 100644
--- a/vlib/v/gen/c/auto_str_methods.v
+++ b/vlib/v/gen/c/auto_str_methods.v
@@ -578,10 +578,14 @@ fn (mut g Gen) gen_str_for_array(info ast.Array, styp string, str_fn_name string
 				deref, deref_label := deref_kind(str_method_expects_ptr, is_elem_ptr,
 					typ)
 				g.auto_str_funcs.writeln('\t\tstring x = _SLIT("nil");')
-				g.auto_str_funcs.writeln('\t\tif (it != 0) {')
+				if !typ.has_flag(.option) {
+					g.auto_str_funcs.writeln('\t\tif (it != 0) {')
+				}
 				g.auto_str_funcs.writeln('\t\t\tstrings__Builder_write_string(&sb, _SLIT("${deref_label}"));')
 				g.auto_str_funcs.writeln('\t\t\tx = ${elem_str_fn_name}(${deref}it);')
-				g.auto_str_funcs.writeln('\t\t}')
+				if !typ.has_flag(.option) {
+					g.auto_str_funcs.writeln('\t\t}')
+				}
 			} else {
 				g.auto_str_funcs.writeln('\t\tstring x = indent_${elem_str_fn_name}(it, indent_count);')
 			}
@@ -610,10 +614,14 @@ fn (mut g Gen) gen_str_for_array(info ast.Array, styp string, str_fn_name string
 			deref, deref_label := deref_kind(str_method_expects_ptr, is_elem_ptr, typ)
 			if is_elem_ptr {
 				g.auto_str_funcs.writeln('\t\tstring x = _SLIT("nil");')
-				g.auto_str_funcs.writeln('\t\tif (it != 0) {')
+				if !typ.has_flag(.option) {
+					g.auto_str_funcs.writeln('\t\tif (it != 0) {')
+				}
 				g.auto_str_funcs.writeln('\t\t\tstrings__Builder_write_string(&sb, _SLIT("${deref_label}"));')
 				g.auto_str_funcs.writeln('\t\t\tx = ${elem_str_fn_name}(${deref}it);')
-				g.auto_str_funcs.writeln('\t\t}')
+				if !typ.has_flag(.option) {
+					g.auto_str_funcs.writeln('\t\t}')
+				}
 			} else {
 				g.auto_str_funcs.writeln('\t\tstrings__Builder_write_string(&sb, _SLIT("${deref_label}"));')
 				g.auto_str_funcs.writeln('\t\tstring x = ${elem_str_fn_name}(${deref}it);')
diff --git a/vlib/v/gen/c/infix.v b/vlib/v/gen/c/infix.v
index 7cc8a50f76..043b83b415 100644
--- a/vlib/v/gen/c/infix.v
+++ b/vlib/v/gen/c/infix.v
@@ -990,7 +990,7 @@ fn (mut g Gen) infix_expr_and_or_op(node ast.InfixExpr) {
 }
 
 fn (mut g Gen) gen_is_none_check(node ast.InfixExpr) {
-	if node.left in [ast.Ident, ast.SelectorExpr] {
+	if node.left in [ast.Ident, ast.SelectorExpr, ast.IndexExpr] {
 		old_inside_opt_or_res := g.inside_opt_or_res
 		g.inside_opt_or_res = true
 		g.expr(node.left)
diff --git a/vlib/v/tests/option_assign_none_test.v b/vlib/v/tests/option_assign_none_test.v
new file mode 100644
index 0000000000..1ed324c7b9
--- /dev/null
+++ b/vlib/v/tests/option_assign_none_test.v
@@ -0,0 +1,11 @@
+fn test_main() {
+	mut a := []?&int{}
+	a << ?&int(none)
+	a << none
+	dump(a[0])
+	dump(a[1])
+	println(a)
+
+	assert a[0] == none
+	assert a[1] == none
+}