<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body style="overflow-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;">I created a reproduction:<div><br></div><div><div style="display: block;"><div style="-webkit-user-select: all; -webkit-user-drag: element; display: inline-block;" class="apple-rich-link" draggable="true" role="link" data-url="https://github.com/rjernst/verify-error-repro"><a style="border-radius:10px;font-family:-apple-system, Helvetica, Arial, sans-serif;display:block;-webkit-user-select:none;width:300px;user-select:none;-webkit-user-modify:read-only;user-modify:read-only;overflow:hidden;text-decoration:none;" class="lp-rich-link" rel="nofollow" href="https://github.com/rjernst/verify-error-repro" dir="ltr" role="button" draggable="false" width="300"><table style="table-layout:fixed;border-collapse:collapse;width:300px;background-color:#E6E6E6;font-family:-apple-system, Helvetica, Arial, sans-serif;" class="lp-rich-link-emailBaseTable" cellpadding="0" cellspacing="0" border="0" width="300"><tbody><tr><td vertical-align="center" align="center"><img style="width:300px;filter:brightness(0.97);height:150px;" width="300" height="150" draggable="false" class="lp-rich-link-mediaImage" alt="verify-error-repro.png" src="cid:D694FD84-13DA-438B-8875-692D912724A8"></td></tr><tr><td vertical-align="center"><table bgcolor="#E6E6E6" cellpadding="0" cellspacing="0" width="300" style="table-layout:fixed;font-family:-apple-system, Helvetica, Arial, sans-serif;background-color:rgba(230, 230, 230, 1);-apple-color-filter:initial;" class="lp-rich-link-captionBar"><tbody><tr><td style="padding:8px 0px 8px 0px;" class="lp-rich-link-captionBar-textStackItem"><div style="max-width:100%;margin:0px 16px 0px 16px;overflow:hidden;" class="lp-rich-link-captionBar-textStack"><div style="word-wrap:break-word;font-weight:500;font-size:12px;overflow:hidden;text-overflow:ellipsis;text-align:left;" class="lp-rich-link-captionBar-textStack-topCaption-leading"><a rel="nofollow" href="https://github.com/rjernst/verify-error-repro" style="text-decoration: none" draggable="false"><font color="#272727" style="color: rgba(0, 0, 0, 0.847059);">rjernst/verify-error-repro</font></a></div><div style="word-wrap:break-word;font-weight:400;font-size:11px;overflow:hidden;text-overflow:ellipsis;text-align:left;" class="lp-rich-link-captionBar-textStack-bottomCaption-leading"><a rel="nofollow" href="https://github.com/rjernst/verify-error-repro" style="text-decoration: none" draggable="false"><font color="#808080" style="color: rgba(0, 0, 0, 0.498039);">github.com</font></a></div></div></td></tr></tbody></table></td></tr></tbody></table></a></div></div><div style="display: block;"><br></div><div style="display: block;">Again, the VerifyError is correct, it’s what we expect (we created bad bytecode in a transform), but it doesn’t always occur.</div><br id="lineBreakAtBeginningOfMessage"><div><br><blockquote type="cite"><div>On Mar 8, 2025, at 12:55 AM, Alan Bateman <Alan.Bateman@oracle.com> wrote:</div><br class="Apple-interchange-newline"><div>
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<div class="moz-cite-prefix">On 07/03/2025 23:50, Ryan Ernst wrote:<br>
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<blockquote type="cite" cite="mid:37F06AA7-E883-4BCF-8E0E-6B2CF1A81FBD@iernst.net">
> <span style="caret-color: rgb(0, 0, 0);">If
the class is loaded and then linked, and is not on the bootstrap
class loader, then it should be verified.</span>
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</span></font></div>
<div><font>I agree, but that’s not what we
observed. We only see the VerifyError if retransformClasses is
called. If instead the class is loaded after the transformer
has been registered, no VerifyError occurs, even though the
transformer produced technically broken bytecode (I say
“technically” because although the parameter type was wrong,
we never used the parameter in this method, so it didn’t
actually cause any problems at runtime, it was just a bad
reference on the stack that was ignored).</font><br>
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<br>
I think the question you are asking is whether there is verification
of classes modified at class load time with a ClassFileTransformer
(ClassFileLoadHook in JVMTI speak) when those classes are in modules
mapped to the boot class loader.<br>
<br>
-Alan<br>
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