RFR: JDK-8303689: javac -Xlint could/should report on "dangling" doc comments

[Magnus Ihse Bursie]

On Wed, 27 Mar 2024 22:04:30 GMT, Jonathan Gibbons <jjg at openjdk.org> wrote:

> Please review the updates to support a proposed new `-Xlint:dangling-doc-comments` option.
> 
> The work can be thought of as in 3 parts:
> 
> 1. An update to the `javac` internal class `DeferredLintHandler` so that it is possible to specify the appropriately configured `Lint` object when it is time to consider whether to generate the diagnostic or not.
> 
> 2. Updates to the `javac` front end to record "dangling docs comments" found near the beginning of a declaration, and to report them using an instance of `DeferredLintHandler`. This allows the warnings to be enabled or disabled using the standard mechanisms for `-Xlint` and `@SuppressWarnings`.  The procedure for handling dangling doc comments is described in this comment in `JavacParser`.
> 
>      *  Dangling documentation comments are handled as follows.
>      *  1. {@code Scanner} adds all doc comments to a queue of
>      *     recent doc comments. The queue is flushed whenever
>      *     it is known that the recent doc comments should be
>      *     ignored and should not cause any warnings.
>      *  2. The primary documentation comment is the one obtained
>      *     from the first token of any declaration.
>      *     (using {@code token.getDocComment()}.
>      *  3. At the end of the "signature" of the declaration
>      *     (that is, before any initialization or body for the
>      *     declaration) any other "recent" comments are saved
>      *     in a map using the primary comment as a key,
>      *     using this method, {@code saveDanglingComments}.
>      *  4. When the tree node for the declaration is finally
>      *     available, and the primary comment, if any,
>      *     is "attached", (in {@link #attach}) any related
>      *     dangling comments are also attached to the tree node
>      *     by registering them using the {@link #deferredLintHandler}.
>      *  5. (Later) Warnings may be genereated for the dangling
>      *     comments, subject to the {@code -Xlint} and
>      *     {@code @SuppressWarnings}.
> 
> 
> 3.  Updates to the make files to disable the warnings in modules for which the 
> warning is generated.  This is often because of the confusing use of `/**` to
> create box or other standout comments.

The build changes look okay. 

Do you have any plan of going through all the Java modules and fixing the issues, or opening JBS issues to have them fixed? Or will these lint warnings remain disabled for the foreseeable future?

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Marked as reviewed by ihse (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/18527#pullrequestreview-1976255818