From 86536e452e6248056666c750668334c7da87202e Mon Sep 17 00:00:00 2001
From: Felipe Pena <felipensp@gmail.com>
Date: Sun, 30 Mar 2025 20:16:16 -0300
Subject: [PATCH] checker: fix check for pushing on an unwrapped option array
 (fix #24073) (#24093)

---
 vlib/v/checker/infix.v                         |  3 +++
 vlib/v/checker/tests/option_array_push.out     |  7 +++++++
 vlib/v/checker/tests/option_array_push.vv      | 18 ++++++++++++++++++
 .../tests/wrong_shift_left_option_err.out      | 14 ++++++++++++++
 4 files changed, 42 insertions(+)
 create mode 100644 vlib/v/checker/tests/option_array_push.out
 create mode 100644 vlib/v/checker/tests/option_array_push.vv

diff --git a/vlib/v/checker/infix.v b/vlib/v/checker/infix.v
index de8f02c36..d69a8d9c3 100644
--- a/vlib/v/checker/infix.v
+++ b/vlib/v/checker/infix.v
@@ -57,6 +57,9 @@ fn (mut c Checker) infix_expr(mut node ast.InfixExpr) ast.Type {
 	}
 	// `arr << if n > 0 { 10 } else { 11 }` set the right c.expected_type
 	if node.op == .left_shift && c.table.sym(left_type).kind == .array {
+		if left_type.has_flag(.option) {
+			c.error('cannot push to Option array that was not unwrapped first', node.left.pos())
+		}
 		c.markused_infiexpr(!c.is_builtin_mod && c.mod != 'strings')
 		if mut node.right is ast.IfExpr {
 			if node.right.is_expr && node.right.branches.len > 0 {
diff --git a/vlib/v/checker/tests/option_array_push.out b/vlib/v/checker/tests/option_array_push.out
new file mode 100644
index 000000000..4c2296d30
--- /dev/null
+++ b/vlib/v/checker/tests/option_array_push.out
@@ -0,0 +1,7 @@
+vlib/v/checker/tests/option_array_push.vv:13:5: error: cannot push to Option array that was not unwrapped first
+   11 | fn my_func(args Struct2) {
+   12 |     mut s1 := args.Struct1
+   13 |     s1.strings << ['hi']
+      |        ~~~~~~~
+   14 | }
+   15 |
diff --git a/vlib/v/checker/tests/option_array_push.vv b/vlib/v/checker/tests/option_array_push.vv
new file mode 100644
index 000000000..bd99293d3
--- /dev/null
+++ b/vlib/v/checker/tests/option_array_push.vv
@@ -0,0 +1,18 @@
+pub struct Struct1 {
+pub mut:
+	strings ?[]string
+}
+
+@[params]
+pub struct Struct2 {
+	Struct1
+}
+
+fn my_func(args Struct2) {
+	mut s1 := args.Struct1
+	s1.strings << ['hi']
+}
+
+s2 := Struct2{}
+
+my_func(s2)
diff --git a/vlib/v/checker/tests/wrong_shift_left_option_err.out b/vlib/v/checker/tests/wrong_shift_left_option_err.out
index 7f6595d2b..abd9f813d 100644
--- a/vlib/v/checker/tests/wrong_shift_left_option_err.out
+++ b/vlib/v/checker/tests/wrong_shift_left_option_err.out
@@ -1,3 +1,10 @@
+vlib/v/checker/tests/wrong_shift_left_option_err.vv:7:2: error: cannot push to Option array that was not unwrapped first
+    5 | fn main() {
+    6 |     mut a := ?[]SomeStruct([SomeStruct{}, SomeStruct{}]) // struct type
+    7 |     a << []SomeStruct{len: 20}
+      |     ^
+    8 |     mut b := ?[]int([2, 8]) // primitive type
+    9 |     b << [1, 3, 4]
 vlib/v/checker/tests/wrong_shift_left_option_err.vv:7:4: error: unwrapped Option cannot be used in an infix expression
     5 | fn main() {
     6 |     mut a := ?[]SomeStruct([SomeStruct{}, SomeStruct{}]) // struct type
@@ -5,6 +12,13 @@ vlib/v/checker/tests/wrong_shift_left_option_err.vv:7:4: error: unwrapped Option
       |       ~~
     8 |     mut b := ?[]int([2, 8]) // primitive type
     9 |     b << [1, 3, 4]
+vlib/v/checker/tests/wrong_shift_left_option_err.vv:9:2: error: cannot push to Option array that was not unwrapped first
+    7 |     a << []SomeStruct{len: 20}
+    8 |     mut b := ?[]int([2, 8]) // primitive type
+    9 |     b << [1, 3, 4]
+      |     ^
+   10 |     dump(a?.len)
+   11 |     dump(b)
 vlib/v/checker/tests/wrong_shift_left_option_err.vv:9:4: error: unwrapped Option cannot be used in an infix expression
     7 |     a << []SomeStruct{len: 20}
     8 |     mut b := ?[]int([2, 8]) // primitive type
-- 
2.39.5