[code-reflection] RFR: Support match all pattern

[Paul Sandoz]

On Mon, 16 Sep 2024 07:47:21 GMT, Mourad Abbay <mabbay at openjdk.org> wrote:

> To lower MatchAllPatternOp, we don't need to do anything, we just skip it, there are no bindings.

It's not that simple :-)

The JLS states [here](https://docs.oracle.com/javase/specs/jls/se22/html/jls-14.html#jls-14.30.1):

Let R be the type of the record pattern r, and let T be the type of the corresponding component field in R 
([§8.10.3](https://docs.oracle.com/javase/specs/jls/se22/html/jls-8.html#jls-8.10.3)). The type of the match-all 
pattern is the upward projection of T with respect to all synthetic type variables mentioned by T.


A record's component still needs to be accessed - its result is not bound to a named variable. e.g., consider:

    record R(Number s) {
        public Number s() {
            if (s instanceof Integer) {
                throw new IllegalArgumentException();
            }
            return s;
        }
    }

    R r = new R(1);
    if (r instanceof R(_)) {
        System.out.println("");
    }


The JLS states [here](https://docs.oracle.com/javase/specs/jls/se22/html/jls-14.html#jls-14.30.2):

A value v that is not the null reference matches a record pattern with type R and component pattern list L if (i) v can be 
converted by testing conversion ([§5.7](https://docs.oracle.com/javase/specs/jls/se22/html/jls-5.html#jls-5.7)) to the target 
type R without raising a ClassCastException; and (ii) each record component of v matches the corresponding component 
pattern in L; and does not match otherwise.

Each record component of v is determined by invoking the accessor method of v corresponding to that component. If 
execution of the invocation of the accessor method completes abruptly for reason S, then pattern matching completes 
abruptly by throwing a MatchException with cause S.

-------------

PR Comment: https://git.openjdk.org/babylon/pull/230#issuecomment-2353804076