On Fri, 6 May 2022 15:44:22 GMT, Gavin Bierman <gbier...@openjdk.org> wrote:
> > From the JLS specdiff
> > > If the type R names a generic record class then it is a compile-time
> > > error if R is not a parameterized type.
> >
> >
> > The following snippet raises a `MatchException`. Shouldn't it be a
> > compile-time error?
> > ```
> > Box<String> r = new Box<>(null);
> >
> > switch (r) {
> > case Box(String s):
> > System.out.println("match");
> > }
> > ```
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > If this is Ok and my understanding is wrong, then why that raises an
> > exception at all? I can make it work (as an unconditional) if I define the
> > Box as `record Box<T extends String>` and now I am confused...
> > ping @GavinBierman @lahodaj
>
> A couple of issues here. (1) This should be a compile-time error. (2) upon
> investigation I think there is a bug with the pattern matching code, because
> the compiler is currently saying that the pattern match here: `Box<String> bs
> = new Box<>(null); if (bs instanceof Box<String>(String s)) {
> System.out.println("match!"); }` does not succeed. (It should do). The
> `MatchException` you are seeing is that the exhaustive pattern switch has no
> matching label (if you put in a default, you don't get the exception).
Right. Will fix. Sorry for that.
-------------
PR: https://git.openjdk.java.net/jdk/pull/8516
