Regression: accessing a private method through a type variable

[Vicente Romero]

Thanks for the report, we have created [1]. I'm taking a look at it,

Vicente

[1] https://bugs.openjdk.org/browse/JDK-8318160

On 10/16/23 07:15, Maurizio Cimadamore wrote:
>
> I recall fixing this a long time ago:
>
>
> https://bugs.openjdk.org/browse/JDK-6711619
>
>
> Now, the test case mentioned in that bug is still correctly rejected 
> by javac. Furhermore, a similar test:
>
>
> ```
> class X<E extends X<E>> {
>              private static int m() { return 1; }
>              int f() {
>                      return E.m();
>              }
>     }
> ```
>
>
> Also fails to compile with 21/22.
>
>
> ```
> Test.java:5: error: m() has private access in X
>                      return E.m();
>                              ^
> 1 error
>
> ```
>
>
> Trying to manipulate Remi's example, it seems the regression only has 
> to do with method refreences whose receiver is a type variable.
>
>
> Here's a minimal reproducer:
>
>
> ```
> import java.util.function.*;
>
> class Test {
>   private String asString() {
>     return "bar";
>   }
>
>   static <T extends Test> Function<T, String> foo() {
>     return T::asString;
>   }
> }
> ```
>
> I filed a bug:
>
>
> https://bugs.openjdk.org/browse/JDK-6711619
>
>
> Thanks
> Maurizio
>
>
> On 16/10/2023 10:40, Sundararajan Athijegannathan wrote:
>> fwiw, this compile from at least JDK 11 onwards:
>>
>> import java.util.*;
>> import java.util.stream.*;
>>
>> public class TDotToString {
>>   class Bar {
>>     private String asString() {
>>       return "bar";
>>     }
>>   }
>>
>>   static <T extends Bar> String foo(List<T> list) {
>>     return list.stream().map(T::asString).collect(Collectors.joining());
>>   }
>> }
>>
>> javac from 1.8.0 does issue error as mentioned by Remi.
>>
>>
>> -Sundar
>> ------------------------------------------------------------------------
>> *From:* compiler-dev <compiler-dev-retn at openjdk.org> on behalf of 
>> Remi Forax <forax at univ-mlv.fr>
>> *Sent:* 16 October 2023 13:57
>> *To:* compiler-dev <compiler-dev at openjdk.org>
>> *Subject:* Regression: accessing a private method through a type 
>> variable
>> Hello,
>> There is a regression in recent versions of javac.
>> javac 21 allows to access a private method through a type variable, 
>> here T::asString.
>>
>> public class TDotToString {
>>   class Bar() {
>>     private String asString() {
>>       return "bar";
>>     }
>>   }
>>
>>   static <T extends Bar> String foo(List<T> list) {
>>     return list.stream().map(T::asString).collect(Collectors.joining());
>>   }
>> }
>>
>> Both IntelliJ and Eclipse emit an error in this case.
>>
>> And javac 8 emits
>>   TDotToString.java:12: error: invalid method reference
>>     return list.stream().map(T::asString).collect(Collectors.joining());
>>                              ^
>>   cannot find symbol
>>     symbol:   method asString()
>>     location: bound of type variable T
>>   where T is a type-variable:
>>     T extends TDotToString.Bar declared in method <T>foo(List<T>)
>> 1 error
>>
>> regards,
>> Rémi
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