ast: make is_int() work with aliases

vlib/v/ast/types.v

@@ -635,7 +635,11 @@ pub fn (t &TypeSymbol) is_pointer() bool {
 
 [inline]
 pub fn (t &TypeSymbol) is_int() bool {
-	return t.kind in [.i8, .i16, .int, .i64, .byte, .u16, .u32, .u64, .int_literal, .rune]
+	res := t.kind in [.i8, .i16, .int, .i64, .byte, .u16, .u32, .u64, .int_literal, .rune]
+	if !res && t.kind == .alias {
+		return (t.info as Alias).parent_type.is_number()
+	}
+	return res
 }
 
 [inline]

vlib/v/checker/checker.v

@@ -3432,7 +3432,7 @@ pub fn (mut c Checker) assign_stmt(mut node ast.AssignStmt) {
 			ast.PrefixExpr {
 				// Do now allow `*x = y` outside `unsafe`
 				if left.op == .mul {
-					if !c.inside_unsafe {
+					if !c.inside_unsafe && !c.pref.translated {
 						c.error('modifying variables via dereferencing can only be done in `unsafe` blocks',
 							node.pos)
 					} else {

vlib/v/tests/type_alias_test.v

@@ -22,6 +22,10 @@ fn test_type_alias_v2() {
 	assert f + f32(0.6) == f32(8.0)
 	g := Myf64_2(10.4)
 	assert g + 0.5 == 10.9
+	// test ++ on an alias
+	mut x := Myint(10)
+	x++
+	assert x == 11
 }
 
 struct Mystruct {