checker: check using literal argument as reference parameter (#14674)

vlib/v/checker/fn.v

@@ -897,6 +897,11 @@ pub fn (mut c Checker) fn_call(mut node ast.CallExpr, mut continue_check &bool)
 			}
 			continue
 		}
+		if param.typ.is_ptr() && !param.is_mut && !call_arg.typ.is_real_pointer()
+			&& call_arg.expr.is_literal() && func.language == .v {
+			c.error('literal argument cannot be passed as reference parameter `${c.table.type_to_str(param.typ)}`',
+				call_arg.pos)
+		}
 		c.check_expected_call_arg(arg_typ, c.unwrap_generic(param.typ), node.language,
 			call_arg) or {
 			if param.typ.has_flag(.generic) {
@@ -1433,6 +1438,10 @@ pub fn (mut c Checker) method_call(mut node ast.CallExpr) ast.Type {
 				}
 				continue
 			}
+			if param.typ.is_ptr() && !arg.typ.is_real_pointer() && arg.expr.is_literal() {
+				c.error('literal argument cannot be passed as reference parameter `${c.table.type_to_str(param.typ)}`',
+					arg.pos)
+			}
 			c.check_expected_call_arg(got_arg_typ, exp_arg_typ, node.language, arg) or {
 				// str method, allow type with str method if fn arg is string
 				// Passing an int or a string array produces a c error here

vlib/v/checker/tests/fn_ref_arg_mismatch_err.out

@@ -0,0 +1,13 @@
+vlib/v/checker/tests/fn_ref_arg_mismatch_err.vv:15:10: error: literal argument cannot be passed as reference parameter `&T`
+   13 | fn main() {
+   14 |     foo := Foo<int>{}
+   15 |     foo.foo(12)
+      |             ~~
+   16 |
+   17 |     bar<int>(12)
+vlib/v/checker/tests/fn_ref_arg_mismatch_err.vv:17:11: error: literal argument cannot be passed as reference parameter `&T`
+   15 |     foo.foo(12)
+   16 |
+   17 |     bar<int>(12)
+      |              ~~
+   18 | }

vlib/v/checker/tests/fn_ref_arg_mismatch_err.vv

@@ -0,0 +1,18 @@
+module main
+
+struct Foo<T> { }
+
+fn (f &Foo<T>) foo(a &T) {
+	println(a)
+}
+
+fn bar<T>(a &T) {
+	println(a)
+}
+
+fn main() {
+	foo := Foo<int>{}
+	foo.foo(12)
+
+	bar<int>(12)
+}