RFR: 8353757: Log class should have a proper clear() method [v2]

[Maurizio Cimadamore]

On Fri, 4 Apr 2025 22:20:28 GMT, Archie Cobbs <acobbs at openjdk.org> wrote:

>> This is a simple refactoring to add a method `Log.clear()`, move `ReusableLog.clear()`'s clearing operations into it and invoke `super.clear()` instead, and add two more fields that should be included in the clear operation but were not because they were added to `Log` after `ReusableLog.clear()` was added and were missed.
>> 
>> A natural question: Are there any other fields in `Log` that should be cleared in `Log.clear()`? The two I've added (`nsuppressederrors` and `nsuppressedwarns`) are the only two that weren't there when `ReusableLog` as added, so presumably not, but it's possible.
>
> Archie Cobbs has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Invoke Log.useSource() before recursing into attribution.

src/jdk.compiler/share/classes/com/sun/tools/javac/util/Log.java line 696:

> 694:      */
> 695:     public void clear() {
> 696:         recorded.clear();

I think the list here is good. There is more state in Log -- but that state seems to be set at creation (e.g. diag listener, writers), while the goal here is to clear up state that "accumulates" from a compilation task.

The thing I'm unsure about is the `diagnosticHandler` field. I suppose we always call "clear" from a context where we already have popped all the installed alternate handlers -- but if not we should reset that too?

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PR Review Comment: https://git.openjdk.org/jdk/pull/24460#discussion_r2030783042