checker: check array sort_with_compare callback function parameters (#13511)

vlib/v/checker/fn.v

@@ -1313,6 +1313,28 @@ pub fn (mut c Checker) method_call(mut node ast.CallExpr) ast.Type {
 					c.fail_if_unreadable(arg.expr, got_arg_typ, 'argument')
 				}
 			}
+			if left_sym.kind == .array && method_name == 'sort_with_compare' {
+				array_info := left_sym.info as ast.Array
+				elem_typ := array_info.elem_type
+				arg_sym := c.table.sym(arg.typ)
+				if arg_sym.kind == .function {
+					func_info := arg_sym.info as ast.FnType
+					if func_info.func.params.len == 2 {
+						if func_info.func.params[0].typ.nr_muls() != elem_typ.nr_muls() + 1 {
+							arg_typ_str := c.table.type_to_str(func_info.func.params[0].typ)
+							expected_typ_str := c.table.type_to_str(elem_typ.ref())
+							c.error('sort_with_compare callback function parameter `${func_info.func.params[0].name}` with type `$arg_typ_str` should be `$expected_typ_str`',
+								func_info.func.params[0].type_pos)
+						}
+						if func_info.func.params[1].typ.nr_muls() != elem_typ.nr_muls() + 1 {
+							arg_typ_str := c.table.type_to_str(func_info.func.params[1].typ)
+							expected_typ_str := c.table.type_to_str(elem_typ.ref())
+							c.error('sort_with_compare callback function parameter `${func_info.func.params[1].name}` with type `$arg_typ_str` should be `$expected_typ_str`',
+								func_info.func.params[1].type_pos)
+						}
+					}
+				}
+			}
 			// Handle expected interface
 			if final_arg_sym.kind == .interface_ {
 				if c.type_implements(got_arg_typ, final_arg_typ, arg.expr.pos()) {

vlib/v/checker/tests/array_sort_with_compare_err.out

@@ -1,3 +1,10 @@
+vlib/v/checker/tests/array_sort_with_compare_err.vv:11:24: error: sort_with_compare callback function parameter `a` with type `string` should be `&string`
+    9 | }
+   10 |
+   11 | fn sort_by_file_base(a string, b string) int {
+      |                        ~~~~~~
+   12 |     return int(a > b)
+   13 | }
 vlib/v/checker/tests/array_sort_with_compare_err.vv:4:26: error: cannot use `fn (string, string) int` as `fn (voidptr, voidptr) int` in argument 1 to `[]string.sort_with_compare`
     2 |     mut names := ['aaa', 'bbb', 'ccc']
     3 |

vlib/v/checker/tests/array_sort_with_compare_ref_elem_err.out

@@ -0,0 +1,7 @@
+vlib/v/checker/tests/array_sort_with_compare_ref_elem_err.vv:21:23: error: sort_with_compare callback function parameter `a` with type `&Cell` should be `&&Cell`
+   19 | }
+   20 |
+   21 | fn sort_cells_by_yx(a &Cell, b &Cell) int {
+      |                       ^
+   22 |     if a.pos.y == b.pos.y {
+   23 |         if a.pos.x < b.pos.x {

vlib/v/checker/tests/array_sort_with_compare_ref_elem_err.vv

@@ -0,0 +1,54 @@
+struct Vec2 {
+	x f32
+	y f32
+}
+
+interface Cell {
+mut:
+	pos Vec2
+}
+
+struct GridCell {
+mut:
+	pos Vec2
+}
+
+pub struct Grid2D {
+mut:
+	cells []&Cell
+}
+
+fn sort_cells_by_yx(a &Cell, b &Cell) int {
+	if a.pos.y == b.pos.y {
+		if a.pos.x < b.pos.x {
+			return -1
+		} else {
+			return 1
+		}
+	} else {
+		if a.pos.y < b.pos.y {
+			return -1
+		} else {
+			return 1
+		}
+	}
+}
+
+fn (mut g Grid2D) sort_cells() {
+	g.cells.sort_with_compare(sort_cells_by_yx)
+}
+
+fn main() {
+	mut grid := Grid2D{}
+	grid.cells << GridCell{
+		pos: Vec2{0, 0}
+	}
+	grid.cells << GridCell{
+		pos: Vec2{1, 0}
+	}
+	grid.cells << GridCell{
+		pos: Vec2{1, 2}
+	}
+	grid.sort_cells()
+	println(grid)
+}