<!DOCTYPE html><html><head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
</head>
<body>
really nice piece of work and badly needed, this area has been a
source of nasty bugs for a while now. This will be a great move to
reduce them and will add a solid base to fix future bugs in this
area,<br>
<br>
Vicente<br>
<br>
<div class="moz-cite-prefix">On 6/13/24 13:05, Maurizio Cimadamore
wrote:<br>
</div>
<blockquote type="cite" cite="mid:c99a9eb1-78a1-4b55-b07a-f74a63e62bb7@oracle.com">
<p><br>
</p>
<div class="moz-cite-prefix">On 13/06/2024 15:31, Archie Cobbs
wrote:<br>
</div>
<blockquote type="cite" cite="mid:CANSoFxuNwYO93KnEB_Jqnb7qiuPjwH3GLiVd2q3wZMfY1kM=8Q@mail.gmail.com">
<div dir="ltr">
<div>Hi Maurizio,</div>
<div><br>
</div>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Thu, Jun 13, 2024 at
5:50 AM Maurizio Cimadamore <<a href="mailto:maurizio.cimadamore@oracle.com" moz-do-not-send="true" class="moz-txt-link-freetext">maurizio.cimadamore@oracle.com</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div>There's also a second, more subtle, implementation
issue, which I'm in the process of evaluating as we
speak. It seems to me that the ordering of the compiler
steps Lower and LambdaToMethod is backwards.</div>
</blockquote>
</div>
<div><br>
</div>
<div>Ah! That helps clarify things for me. Thanks for your
analysis.</div>
<div><br>
</div>
<div>-Archie<br>
</div>
<div><br>
</div>
<span class="gmail_signature_prefix">-- </span><br>
<div dir="ltr" class="gmail_signature">Archie L. Cobbs<br>
</div>
</div>
</blockquote>
<p>Here's a first draft of the work to move LambdaToMethod after
Lower:</p>
<p><a class="moz-txt-link-freetext" href="https://github.com/mcimadamore/jdk/pull/new/cleanup_capture" moz-do-not-send="true">https://github.com/mcimadamore/jdk/pull/new/cleanup_capture</a></p>
<p>Things went considerably smooth, given the depth of the
surgery. Some notable facts:<br>
<br>
1. now LambdaToMethod deals with separate classes, not a single
toplevel one (as it now occurs _after_ lowering)<br>
2. Lower needs a to override `visitLambda`, so that it can
properly lower the lambda return expressions<br>
3. The code to "desugars" complex method references into lambdas
has been moved from LambdaToMethod to Lower (so that we can
fixup references to inner classes etc.)<br>
4. The method reference receiver of desugared lambda expression
is now stashed into the JCLambda AST (as LambdaToMethod will
need that later)<br>
5. the lambda deserialization method generated by LambdaToMethod
contains string in switch, and implicitly requires boxing, so we
need to explictly lower that<br>
6. some code generated by Lower is not stable, so lambda
deduplication fails in new ways</p>
<p>The nice thing about this cleanup is that a ton of questionable
stuff just disappears:</p>
<p>* no need to have a "lambdaTranslationMap" in Lower. This was
only needed when a lambda expression anticipated capture later
required from Lower but that did not appear in the source code
(yet)<br>
* no need to have "typesUnderConstruction" (and associated
visitors) in LambdaToMethod. As now lambda translation occurs
_after_ inner class translation, LambdaToMethod can expect that
references to enclosing instances have already been figured out
by Lower<br>
* no more need to "guess" captured values for local classes
inside a lambda - the required captured values are now made
explicit in the AST. This means we don't need to run a modified
FreeVarCollector inside LambdaToMethod</p>
<p>All this means is that stuff like this:</p>
<p><a class="moz-txt-link-freetext" href="https://bugs.openjdk.org/browse/JDK-8334037" moz-do-not-send="true">https://bugs.openjdk.org/browse/JDK-8334037</a></p>
<p>Just works. And, if we make improvements in Lower to fix the
issues with local and anonymous classes and inaccessible
enclosing instances, then LambdaToMethod will work w/o any
manual adjustment required.</p>
<p>Of course, this is a biggie piece of work, so I don't think we
should do it for 23, as we're already past RDP1. More testing is
also needed. But, a promising start.</p>
<p>Cheers<br>
Maurizio<br>
</p>
<p><br>
</p>
</blockquote>
<br>
</body>
</html>