checker: fix check for pushing on an unwrapped option array (fix #24073) (#24093)

Author: felipensp

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 {

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 |

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)

vlib/v/checker/tests/wrong_shift_left_option_err.out

@@ -1,10 +1,24 @@
+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
     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: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