checker: disallow invalid ptr operations (#21515)

Author: Delta456

vlib/v/checker/infix.v

@@ -331,6 +331,12 @@ fn (mut c Checker) infix_expr(mut node ast.InfixExpr) ast.Type {
 				}
 			}
 
+			if ((unwrapped_left_type.is_ptr() && !node.left.is_auto_deref_var())
+				|| (unwrapped_right_type.is_ptr() && !node.right.is_auto_deref_var()))
+				&& node.op !in [.plus, .minus] {
+				c.error('infix `${node.op}` is not defined for pointer values', left_right_pos)
+			}
+
 			if !c.pref.translated && left_sym.kind in [.array, .array_fixed, .map, .struct_] {
 				if left_sym.has_method_with_generic_parent(node.op.str()) {
 					if method := left_sym.find_method_with_generic_parent(node.op.str()) {

vlib/v/checker/tests/disallow_pointer_arithmetic_err.out

@@ -25,10 +25,24 @@ vlib/v/checker/tests/disallow_pointer_arithmetic_err.vv:5:7: error: invalid oper
       |          ~~~~~
     6 |     _ := p * 2 //should be error
     7 |     _ := p + 5 //OK but only in unsafe block, r is *int
+vlib/v/checker/tests/disallow_pointer_arithmetic_err.vv:5:7: error: infix `*` is not defined for pointer values
+    3 |     p := &x
+    4 |     _ := p + p //should be error
+    5 |     _ := p * p //should be error
+      |          ~~~~~
+    6 |     _ := p * 2 //should be error
+    7 |     _ := p + 5 //OK but only in unsafe block, r is *int
 vlib/v/checker/tests/disallow_pointer_arithmetic_err.vv:6:7: error: invalid operator `*` to `&int` and `int literal`
     4 |     _ := p + p //should be error
     5 |     _ := p * p //should be error
     6 |     _ := p * 2 //should be error
       |          ~~~~~
     7 |     _ := p + 5 //OK but only in unsafe block, r is *int
     8 |     _ := p - p //OK even in safe code, but n should be isize
+vlib/v/checker/tests/disallow_pointer_arithmetic_err.vv:6:7: error: infix `*` is not defined for pointer values
+    4 |     _ := p + p //should be error
+    5 |     _ := p * p //should be error
+    6 |     _ := p * 2 //should be error
+      |          ~~~~~
+    7 |     _ := p + 5 //OK but only in unsafe block, r is *int
+    8 |     _ := p - p //OK even in safe code, but n should be isize

vlib/v/checker/tests/invalid_op_ptr_err.out

@@ -0,0 +1,14 @@
+vlib/v/checker/tests/invalid_op_ptr_err.vv:3:6: error: infix `*` is not defined for pointer values
+    1 | num := 10
+    2 | p := &num
+    3 | x := 5 * p
+      |      ~~~~~
+    4 | y := 5 / p
+    5 | dump(x)
+vlib/v/checker/tests/invalid_op_ptr_err.vv:4:6: error: infix `/` is not defined for pointer values
+    2 | p := &num
+    3 | x := 5 * p
+    4 | y := 5 / p
+      |      ~~~~~
+    5 | dump(x)
+    6 | dump(p)

vlib/v/checker/tests/invalid_op_ptr_err.vv

@@ -0,0 +1,7 @@
+num := 10
+p := &num
+x := 5 * p
+y := 5 / p
+dump(x)
+dump(p)
+dump(y)

vlib/v/checker/tests/pointer_ops.out

@@ -54,6 +54,13 @@ vlib/v/checker/tests/pointer_ops.vv:15:3: error: invalid operator `%` to `&Foo`
       |         ~~~~~~~
    16 |     }
    17 | }
+vlib/v/checker/tests/pointer_ops.vv:15:3: error: infix `%` is not defined for pointer values
+   13 |         _ = p[3]
+   14 |         mut foo := &Foo{}
+   15 |         foo % 3
+      |         ~~~~~~~
+   16 |     }
+   17 | }
 vlib/v/checker/tests/pointer_ops.vv:15:3: error: mismatched types `&Foo` and `int literal`
    13 |         _ = p[3]
    14 |         mut foo := &Foo{}
@@ -117,6 +124,13 @@ vlib/v/checker/tests/pointer_ops.vv:30:3: error: invalid operator `%` to `&Foo`
       |         ~~~~~~~
    31 |     }
    32 | }
+vlib/v/checker/tests/pointer_ops.vv:30:3: error: infix `%` is not defined for pointer values
+   28 |         _ = p[3]
+   29 |         mut foo := &Foo{}
+   30 |         foo % 3
+      |         ~~~~~~~
+   31 |     }
+   32 | }
 vlib/v/checker/tests/pointer_ops.vv:30:3: error: mismatched types `&Foo` and `int literal`
    28 |         _ = p[3]
    29 |         mut foo := &Foo{}