checker, cgen: fix type alias of pointer (#17904)

vlib/v/checker/return.v

@@ -219,8 +219,9 @@ fn (mut c Checker) return_stmt(mut node ast.Return) {
 					pos)
 			}
 		}
-		if (got_typ.is_ptr() || got_typ.is_pointer())
-			&& (!exp_type.is_ptr() && !exp_type.is_pointer()) {
+		unaliased_exp_typ := c.table.unaliased_type(exp_type)
+		if got_typ.is_real_pointer() && !exp_type.is_real_pointer()
+			&& !unaliased_exp_typ.is_real_pointer() {
 			pos := node.exprs[expr_idxs[i]].pos()
 			if node.exprs[expr_idxs[i]].is_auto_deref_var() {
 				continue
@@ -230,7 +231,7 @@ fn (mut c Checker) return_stmt(mut node ast.Return) {
 				pos)
 		}
 		unaliased_got_typ := c.table.unaliased_type(got_typ)
-		if (exp_type.is_ptr() || exp_type.is_pointer()) && !got_typ.is_real_pointer()
+		if exp_type.is_real_pointer() && !got_typ.is_real_pointer()
 			&& !unaliased_got_typ.is_real_pointer() && got_typ != ast.int_literal_type
 			&& !c.pref.translated && !c.file.is_translated {
 			pos := node.exprs[expr_idxs[i]].pos()

vlib/v/gen/c/fn.v

@@ -2351,8 +2351,8 @@ fn (mut g Gen) keep_alive_call_postgen(node ast.CallExpr, tmp_cnt_save int) {
 fn (mut g Gen) ref_or_deref_arg(arg ast.CallArg, expected_type ast.Type, lang ast.Language) {
 	arg_typ := g.unwrap_generic(arg.typ)
 	arg_sym := g.table.sym(arg_typ)
-	exp_is_ptr := expected_type.is_ptr() || expected_type.idx() in ast.pointer_type_idxs
-	arg_is_ptr := arg_typ.is_ptr() || arg_typ.idx() in ast.pointer_type_idxs
+	exp_is_ptr := expected_type.is_real_pointer()
+	arg_is_ptr := arg_typ.is_real_pointer()
 	if expected_type == 0 {
 		g.checker_bug('ref_or_deref_arg expected_type is 0', arg.pos)
 	}
@@ -2360,7 +2360,8 @@ fn (mut g Gen) ref_or_deref_arg(arg ast.CallArg, expected_type ast.Type, lang as
 	mut needs_closing := false
 	if arg.is_mut && !exp_is_ptr {
 		g.write('&/*mut*/')
-	} else if exp_is_ptr && !arg_is_ptr {
+	} else if exp_is_ptr && !arg_is_ptr && !(arg_sym.kind == .alias
+		&& g.table.unaliased_type(arg_typ).is_pointer() && expected_type.is_pointer()) {
 		if arg.is_mut {
 			if exp_sym.kind == .array {
 				if (arg.expr is ast.Ident && (arg.expr as ast.Ident).kind == .variable)

vlib/v/tests/type_alias_of_pointer_types_test.v

@@ -72,3 +72,24 @@ fn mut_alias(mut ps PZZMyStructInt) int {
 	//	dump(ptr_str(voidptr(ps)))
 	return 123
 }
+
+type HANDLE = voidptr
+
+fn example(arg voidptr) {
+	println('Handle value in function is: ${arg}')
+	assert '${arg}' == '0'
+}
+
+fn test_alias_of_pointer() {
+	handle := get_handle()
+
+	println('Actual handle value is: ${handle}')
+	println('Memory address of handle is: ${&handle}')
+
+	example(handle)
+	assert '${handle}' == '0'
+}
+
+fn get_handle() HANDLE {
+	return unsafe { nil }
+}