<div dir="ltr"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">Then perhaps the cleaner fix is instead to have the default methods delegate to `LocalVariable.of(int,String,ClassDesc,Label,Label)` directly?</div></div><br><div class="gmail_quote gmail_quote_container"><div dir="ltr" class="gmail_attr">On Wed, Oct 1, 2025 at 7:52 AM Brian Goetz <<a href="mailto:brian.goetz@oracle.com">brian.goetz@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"><u></u>
<div>
<font size="4" face="monospace">After thinking about it for a few
more minutes, I'm less sure of this approach (and not sure I'd
even classify it as a bug.) While locally this change is probably
harmless, there are dozens of uses of the idiom
`constantPool().xxxEntry()` in this class -- why would we switch
just some of them over to using the temp pool? And switching all
of them over falls into a more significant change in
implementation approach, for which the bar is surely higher. <br>
<br>
In any case, I think we don't need to change anything; the code
you want is already in the library. Just do<br>
<br>
builder.with(LocalVariable.of(slot, name, desc, start, end))<br>
<br>
since that's exactly what LocalVariable::of does:<br>
<br>
</font>
<div style="background-color:rgb(255,255,255);color:rgb(8,8,8)">
<pre style="font-family:"JetBrains Mono",monospace;font-size:11.3pt"> <span style="color:rgb(0,51,179)">static </span><span style="color:rgb(0,0,0)">LocalVariable </span><span style="color:rgb(0,98,122)">of</span>(<span style="color:rgb(0,51,179)">int </span><span style="color:rgb(0,0,0)">slot</span>, <span style="color:rgb(0,0,0)">String name</span>, <span style="color:rgb(0,0,0)">ClassDesc descriptor</span>, <span style="color:rgb(0,0,0)">Label startScope</span>, <span style="color:rgb(0,0,0)">Label endScope</span>) {
<span style="color:rgb(0,51,179)">return </span><span style="font-style:italic">of</span>(<span style="color:rgb(0,0,0)">slot</span>,
<span style="color:rgb(0,0,0)">TemporaryConstantPool</span>.<span style="color:rgb(135,16,148);font-style:italic">INSTANCE</span>.utf8Entry(<span style="color:rgb(0,0,0)">name</span>),
<span style="color:rgb(0,0,0)">TemporaryConstantPool</span>.<span style="color:rgb(135,16,148);font-style:italic">INSTANCE</span>.utf8Entry(<span style="color:rgb(0,0,0)">descriptor</span>.descriptorString()),
<span style="color:rgb(0,0,0)">startScope</span>, <span style="color:rgb(0,0,0)">endScope</span>);
}
}
</pre>
</div>
<br>
<font size="4" face="monospace"><br>
<br>
<br>
<br>
<br>
</font><br>
<div>On 10/1/2025 8:31 AM, David Lloyd
wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_default" style="font-family:arial,helvetica,sans-serif">OK, shall I
prepare a bug report and patch? Thanks.</div>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Tue, Sep 30, 2025 at
2:55 PM Chen Liang <<a href="mailto:chen.l.liang@oracle.com" target="_blank">chen.l.liang@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>
<div dir="ltr">
<div style="font-family:"Calibri Light","Helvetica Light",sans-serif;font-size:12pt;color:rgb(0,0,0)">
Hi David, this seems a legitimate bug.</div>
<div style="font-family:"Calibri Light","Helvetica Light",sans-serif;font-size:12pt;color:rgb(0,0,0)">
<br>
</div>
<div style="font-family:"Calibri Light","Helvetica Light",sans-serif;font-size:12pt;color:rgb(0,0,0)">
I think we can bypass this by using the
TemporaryConstantPool.INSTANCE to construct the UTF-8
entries.</div>
<div style="font-family:"Calibri Light","Helvetica Light",sans-serif;font-size:12pt;color:rgb(0,0,0)">
<br>
</div>
<div style="font-family:"Calibri Light","Helvetica Light",sans-serif;font-size:12pt;color:rgb(0,0,0)">
Regards, Chen</div>
<hr style="display:inline-block;width:98%">
<div id="m_-3895197113871837706m_-3732124551141255202divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> classfile-api-dev <<a href="mailto:classfile-api-dev-retn@openjdk.org" target="_blank">classfile-api-dev-retn@openjdk.org</a>>
on behalf of David Lloyd <<a href="mailto:david.lloyd@redhat.com" target="_blank">david.lloyd@redhat.com</a>><br>
<b>Sent:</b> Tuesday, September 30, 2025 11:07 AM<br>
<b>To:</b> <a href="mailto:classfile-api-dev@openjdk.org" target="_blank">classfile-api-dev@openjdk.org</a>
<<a href="mailto:classfile-api-dev@openjdk.org" target="_blank">classfile-api-dev@openjdk.org</a>><br>
<b>Cc:</b> Ladislav Thon <<a href="mailto:lthon@redhat.com" target="_blank">lthon@redhat.com</a>><br>
<b>Subject:</b> DROP_DEBUG and the constant pool</font>
<div> </div>
</div>
<div>
<div dir="ltr">
<div>
<div style="font-family:arial,helvetica,sans-serif">We've
observed that when using `DROP_DEBUG` in
conjunction with `CodeBuilder#localVariable`
and/or `localVariableType`, some (otherwise
useless) constant pool entries are still being
created (which contain, I believe, both the
variable name and descriptor). This was observed
using a backport of the JDK classfile API based on
JDK 25.</div>
<br clear="all">
</div>
<div>
<div style="font-family:arial,helvetica,sans-serif">Would
this be expected behavior? Is there a separate
step needed to clean the constant pool for cases
like this?</div>
</div>
<div style="font-family:arial,helvetica,sans-serif"><br>
</div>
<div style="font-family:arial,helvetica,sans-serif">It
looks to me to be the consequence of how the default
methods for local variable creation are implemented,
e.g.:</div>
<div style="font-family:arial,helvetica,sans-serif"><br>
</div>
<div style="font-family:arial,helvetica,sans-serif">
default CodeBuilder localVariable(int slot, String
name, ClassDesc descriptor, Label startScope, Label
endScope) {<br>
return localVariable(slot,<br>
constantPool().utf8Entry(name),<br>
constantPool().utf8Entry(descriptor),<br>
startScope, endScope);<br>
}<br>
</div>
<div><br>
</div>
<div>
<div style="font-family:arial,helvetica,sans-serif">The
constant pool is accessed even when `DROP_DEBUG`
is enabled, because that flag is used later on in
the process, and it seems that these entries are
never dropped, even if they are unused.</div>
<br>
</div>
<span>-- </span><br>
<div dir="ltr">
<div dir="ltr">- DML • he/him<br>
</div>
</div>
</div>
</div>
</div>
</div>
</blockquote>
</div>
<div><br clear="all">
</div>
<div><br>
</div>
<span class="gmail_signature_prefix">-- </span><br>
<div dir="ltr" class="gmail_signature">
<div dir="ltr">- DML • he/him<br>
</div>
</div>
</blockquote>
<br>
</div>
</blockquote></div><div><br clear="all"></div><div><br></div><span class="gmail_signature_prefix">-- </span><br><div dir="ltr" class="gmail_signature"><div dir="ltr">- DML • he/him<br></div></div>