RFR: 8338910: [lw5] enhance the Signature attribute to represent nullability [v2]

[Maurizio Cimadamore]

On Sun, 25 Aug 2024 19:54:44 GMT, Vicente Romero <vromero at openjdk.org> wrote:

>> Enhance the Signature attribute so that we can represent nullability and null restrictions
>
> Vicente Romero has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains two commits:
> 
>  - merge with lw5
>  - 8338910: [lw5] enhance the Signature attribute to represent nullability

src/jdk.compiler/share/classes/com/sun/tools/javac/code/Types.java line 5314:

> 5312:                     append('T');
> 5313:                     append(type.tsym.name);
> 5314:                     NullMarker nullMarker = type.getNullMarker();

Better to use the predicates in `Types` which take into account the command line options (e.g. whether to treat type-variables as `*` or not) ?

src/jdk.compiler/share/classes/com/sun/tools/javac/jvm/ClassReader.java line 599:

> 597:                         ClassType res = new ClassType(et.getEnclosingType(), List.nil(), et.tsym, et.getMetadata());
> 598:                         if (nm != NullMarker.UNSPECIFIED) {
> 599:                             res = (ClassType) res.addMetadata(new TypeMetadata.NullMarker(nm));

We have an `asNullMarked` to create nullness-marked types

test/langtools/tools/javac/nullability/NullabilitySignatureAttrTests.java line 91:

> 89:                     }
> 90:                     """,
> 91:                     "LTest!;"

My feeling is that the `!`/`?` should go _before_ the type in the sig attribute, similar to what we do for arrays and wildcards. Otherwise parsing becomes more complex.

test/langtools/tools/javac/nullability/NullabilitySignatureAttrTests.java line 156:

> 154: 
> 155:     /*@Test
> 156:     void testCheckFieldSignature() throws Exception {

This should be uncommented?

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PR Review Comment: https://git.openjdk.org/valhalla/pull/1223#discussion_r1731050961
PR Review Comment: https://git.openjdk.org/valhalla/pull/1223#discussion_r1731053700
PR Review Comment: https://git.openjdk.org/valhalla/pull/1223#discussion_r1731057487
PR Review Comment: https://git.openjdk.org/valhalla/pull/1223#discussion_r1731056375