RFR: 8291643: Consider omitting type annotations from type error diagnostics [v3]

[Vicente Romero]

On Tue, 4 Jun 2024 18:03:44 GMT, Liam Miller-Cushon <cushon at openjdk.org> wrote:

>> Hi,
>> 
>> Please consider this fix for [JDK-8291643](https://bugs.openjdk.org/browse/JDK-8291643), which causes javac to remove type-use annotations when formatting types in diagnostics.
>> 
>> For the example like the one in the bug, this change causes javac to emit the diagnostic like `incompatible types: List<String> cannot be converted to List<Number>` rather than `incompatible types: List<String> cannot be converted to List<@Nullable Number>`. Including the type annotations can be confusing, because they do not impact the type checking done by the compiler.
>> 
>> An alternative I considered was to remove type annotations from types for specific diagnostics, instead of doing it unconditionally in diagnostic formatting. I can revisit that if the current approach seems too broad.
>> 
>> The test update to `test/langtools/tools/javac/lambda/LambdaConv25.out` is because a `ForAll` is being formatted, and `stripMetadata()` uses a `StructuralTypeMapping` which rewrites away the `ForAll`.
>
> Liam Miller-Cushon 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 seven additional commits since the last revision:
> 
>  - Update after merge of JDK-8043226
>  - Merge remote-tracking branch 'origin/master' into JDK-8291643
>  - Merge branch 'master' into JDK-8291643
>  - Use Type stripping logic added for JDK-8042981
>  - Merge branch 'master' into JDK-8291643
>  - Updates based on review thread
>    
>    * Support optionally printing types with type annotations
>    * Move handling of types in AbstractDiagnosticFormatter
>    * Make annotation removal more robust, don't rely on stripMetadata
>  - 8291643: Consider omitting type annotations from type error diagnostics

lgtm

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Marked as reviewed by vromero (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/16578#pullrequestreview-2097447990