8369517: Compilation mismatch for equivalent lambda and method reference

[vicente-romero-oracle]

Given the following test case:

import java.util.function.Supplier;
interface Main {
    interface X<T> {
        X<T> self();
    }

    static X<?> makeX() {return null;}

    static <R> X<R> create(Supplier<? extends R> supplier) {return null;}

    static X<X<?>> methodRef() {
        return create(Main::makeX).self();
    }

    static X<X<?>> lambda() {
        return create(() -> makeX()).self();
    }
}

javac reports an error for the method reference but not for the lambda. There should be no difference here (error in both cases)

---

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• Commit message must refer to an issue
• Change requires CSR request JDK-8369518 to be approved

Issues

• JDK-8369517: Compilation mismatch for equivalent lambda and method reference (Bug - P4)
• JDK-8369518: Compilation mismatch for equivalent lambda and method reference (CSR)

Reviewers

• Maurizio Cimadamore (@mcimadamore - Reviewer)

Reviewing

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[vicente-romero-oracle]

/csr needed

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8369517: Compilation mismatch for equivalent lambda and method reference

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[openjdk]

@vicente-romero-oracle has indicated that a compatibility and specification (CSR) request is needed for this pull request.

@vicente-romero-oracle please create a CSR request for issue JDK-8369517 with the correct fix version. This pull request cannot be integrated until the CSR request is approved.

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[mlbridge]

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• 03: Full - Incremental (1efd9f87)
• 02: Full - Incremental (53f7d475)
• 01: Full - Incremental (41783b0f)
• 00: Full (8005b675)

[liach]

Suggested change

	var s = (String)create(Main::makeX);
	var s = (String)create(ResultTypeNotBeingCapturedTest::makeX);

Please also update the .out output, which should be more consistent after this fix.

[vicente-romero-oracle]

yep thanks I saw that too, copy paste bug :)

[mcimadamore]

The original test from Tagir was slightly different -- maybe we want to use that one instead?

I think it was return create(...).self()

[mcimadamore]

The fix looks good!

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[vicente-romero-oracle]

/integrate

[openjdk]

Going to push as commit e5a272a.
Since your change was applied there have been 15 commits pushed to the master branch:

• 1f1f7bb: 8370024: HttpClient: QUIC congestion controller doesn't implement pacing
• 400a83d: 8371625: G1: G1HeapRegion::print_on misalignment
• 76a0732: 8366691: JShell should support a more convenient completion
• ... and 12 more: https://git.openjdk.org/jdk/compare/43afce54a7ecbd124f68f1f32d718f08b24ca61a...master

Your commit was automatically rebased without conflicts.

[openjdk]

@vicente-romero-oracle Pushed as commit e5a272a.

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