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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - REGRESSION (r200946): Improper backtracking from last alternative in sticky patterns"
href="https://bugs.webkit.org/show_bug.cgi?id=159233">159233</a>
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<th>Summary</th>
<td>REGRESSION (r200946): Improper backtracking from last alternative in sticky patterns
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<th>Classification</th>
<td>Unclassified
</td>
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<th>Product</th>
<td>WebKit
</td>
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<th>Version</th>
<td>WebKit Nightly Build
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<th>Hardware</th>
<td>Unspecified
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<th>OS</th>
<td>Unspecified
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>Normal
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<th>Priority</th>
<td>P2
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<th>Component</th>
<td>JavaScriptCore
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<th>Assignee</th>
<td>webkit-unassigned@lists.webkit.org
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<th>Reporter</th>
<td>msaboff@apple.com
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<pre>Various sticky patterns fail in unexpected ways when the last alternative doesn't match. It seems that we retry with an index that isn't correct. This manifests itself in a couple different ways.
The expression 's = ”\n”.split(/.{2}|(?=$)./ym)' will crash in JIT'ed code, while the expression 'let m = ".a".match(/x(.)|[-\d]/gy")' will ASSERT in debug builds:
#0 0x106b8ccb8 in WTFCrash (JavaScriptCore+0x2a87cb8)
#1 0x1066e889a in JSC::JSRopeString::finishCreationSubstringOfResolved(JSC::VM&, JSC::JSString*, unsigned int, unsigned int) (JavaScriptCore+0x25e389a)
#2 0x1066e8176 in JSC::JSRopeString::createSubstringOfResolved(JSC::VM&, JSC::JSString*, unsigned int, unsigned int) (JavaScriptCore+0x25e3176)
#3 0x1066fa423 in JSC::JSValue JSC::collectMatches<JSC::RegExpObject::matchGlobal(JSC::ExecState*, JSC::JSGlobalObject*, JSC::JSString*)::$_1>(JSC::VM&, JSC::ExecState*, JSC::JSString*, WTF::String const&, JSC::RegExpConstructor*, JSC::RegExp*, JSC::RegExpObject::matchGlobal(JSC::ExecState*, JSC::JSGlobalObject*, JSC::JSString*)::$_1 const&)::'lambda'()::operator()() const (JavaScriptCore+0x25f5423)
#4 0x1066f89b3 in JSC::JSValue JSC::collectMatches<JSC::RegExpObject::matchGlobal(JSC::ExecState*, JSC::JSGlobalObject*, JSC::JSString*)::$_1>(JSC::VM&, JSC::ExecState*, JSC::JSString*, WTF::String const&, JSC::RegExpConstructor*, JSC::RegExp*, JSC::RegExpObject::matchGlobal(JSC::ExecState*, JSC::JSGlobalObject*, JSC::JSString*)::$_1 const&) (JavaScriptCore+0x25f39b3)
#5 0x1066f6c90 in JSC::RegExpObject::matchGlobal(JSC::ExecState*, JSC::JSGlobalObject*, JSC::JSString*) (JavaScriptCore+0x25f1c90)</pre>
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