checker: fix missing incompatible pushval type for chan <- operator (#21040)

vlib/v/checker/infix.v

@@ -705,7 +705,8 @@ fn (mut c Checker) infix_expr(mut node ast.InfixExpr) ast.Type {
 				chan_info := left_sym.chan_info()
 				elem_type := chan_info.elem_type
 				if !c.check_types(right_type, elem_type) {
-					c.error('cannot push `${right_sym.name}` on `${left_sym.name}`', right_pos)
+					c.error('cannot push `${c.table.type_to_str(right_type)}` on `${left_sym.name}`',
+						right_pos)
 				}
 				if chan_info.is_mut {
 					// TODO: The error message of the following could be more specific...
@@ -714,6 +715,9 @@ fn (mut c Checker) infix_expr(mut node ast.InfixExpr) ast.Type {
 				if elem_type.is_ptr() && !right_type.is_ptr() {
 					c.error('cannot push non-reference `${right_sym.name}` on `${left_sym.name}`',
 						right_pos)
+				} else if right_type.is_ptr() != elem_type.is_ptr() {
+					c.error('cannot push `${c.table.type_to_str(right_type)}` on `${left_sym.name}`',
+						right_pos)
 				}
 				c.stmts_ending_with_expression(mut node.or_block.stmts)
 			} else {

vlib/v/checker/tests/chan_incompatible_type_err.out

@@ -0,0 +1,6 @@
+vlib/v/checker/tests/chan_incompatible_type_err.vv:6:11: error: cannot push `&Foo` on `chan Foo`
+    4 |     ch := chan Foo{}
+    5 |     foo := Foo{}
+    6 |     ch <- &foo
+      |           ^
+    7 | }

vlib/v/checker/tests/chan_incompatible_type_err.vv

@@ -0,0 +1,7 @@
+struct Foo {}
+
+fn main() {
+    ch := chan Foo{}
+    foo := Foo{}
+    ch <- &foo
+}