RFR: Classfile signature bang support [v2]

[Maurizio Cimadamore]

On Tue, 20 Jan 2026 21:23:41 GMT, Chen Liang <liach at openjdk.org> wrote:

>> Support parsing ! signatures in ClassFile API.
>
> Chen Liang has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains three additional commits since the last revision:
> 
>  - Review, various cleanup
>  - Merge branch 'bworld' of https://github.com/openjdk/valhalla into feature/cf-bang-sig
>  - Classfile signature bang support

Looks good - I've left some doc notes and some test comments

src/java.base/share/classes/java/lang/classfile/Signature.java line 295:

> 293: 
> 294:         /**
> 295:          * {@return a class or interface signature without an outer type}

Maybe we should say that, by default, the returned signature is NOT null marked?

src/java.base/share/classes/jdk/internal/classfile/impl/SignaturesImpl.java line 212:

> 210:             boolean end = match(';');
> 211:             if (end || match('.')) {
> 212:                 t = new ClassTypeSigImpl(RefTypeSig.NullMarker.UNSPECIFIED, Optional.ofNullable(t), className, null2Empty(argTypes));

Why not going through the `of` factory?

test/jdk/jdk/classfile/SignaturesTest.java line 409:

> 407:                 <:Ljava/lang/Object;>Ljava/lang/Object;
> 408:                 <>Ljava/lang/Object;
> 409:                 !Ljava/lang/Object;

Why is this "bad" ?

test/jdk/jdk/classfile/SignaturesTest.java line 411:

> 409:                 !Ljava/lang/Object;
> 410:                 Ljava/lang/Object;!Ljava/lang/Runnable;
> 411:                 <>Ljava/lang/Object;

This test line seems repeated? Or did you want to add a `!` here?

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Marked as reviewed by mcimadamore (Committer).

PR Review: https://git.openjdk.org/valhalla/pull/1933#pullrequestreview-3688086862
PR Review Comment: https://git.openjdk.org/valhalla/pull/1933#discussion_r2713246252
PR Review Comment: https://git.openjdk.org/valhalla/pull/1933#discussion_r2713269249
PR Review Comment: https://git.openjdk.org/valhalla/pull/1933#discussion_r2713278798
PR Review Comment: https://git.openjdk.org/valhalla/pull/1933#discussion_r2713275824