I have witnessed some - imo odd - GWT behavior regarding stacktrace
accuracy that I cannot yet fully comprehend, so I am posting it here.
I have a GWT application of which the .gwt.xml file contains these three
lines:
<set-property name="compiler.stackMode" value="emulated" />
<set-configuration-property name="compiler.emulatedStack.recordLineNumbers"
value="true"/>
<set-configuration-property name="compiler.emulatedStack.recordFileNames"
value="true"/>
Also, I ensured a StringOutOfBoundsException to occur on a distinct screen
by doing this:
GWT.log("123".substring(65));
in *SomePanel.java* on line *195*.
To conclude, I made two release builds: 'build A' and 'build B'. A and B
are identical, except for B *not* having any symbol maps present in the
resulting file structure (they are manually removed post-compilation)
before a distributable zip file is made. The omission of the symbol map
files is an attempt to no longer enable end users to be able to view
deobfuscated stacktraces directly in the browser's console or to perform
deobfuscation manually offline.
When navigating to the broken screen of build A, the stacktrace that is
printed to the browser's console is deobfuscated (duh) and - more
importantly - 100% correct regarding file names and line numbers.
Therefore, it's straightforward to pinpoint where any issue did occur in
the original Java code.
When navigating to the broken screen of build B, the stacktrace that is
printed to the browser's console is obfuscated, but ... wrong in terms of
file names and line numbers... This is the stacktrace that was printed out
in the browser's console in this occasion:
java.lang.StringIndexOutOfBoundsException: Index: 65, Size: 4
at Unknown.qXf(Throwable.java:66)
at Unknown.CXf(Exception.java:29)
at Unknown.H3f(RuntimeException.java:29)
at Unknown.bop(IndexOutOfBoundsException.java:29)
at Unknown.wrp(StringIndexOutOfBoundsException.java:30)
at Unknown.OKp(InternalPreconditions.java:487)
at Unknown.pwf(InternalPreconditions.java:475)
at Unknown.hbe(NavigationManager.java:287)
at Unknown.kbe(NavigationManager.java:118)
at Unknown.RPe(MainPanel.java:604)
at Unknown.Ung(ValueChangeEvent.java:128)
at Unknown.hog(GwtEvent.java:76)
at Unknown._ng(SimpleEventBus.java:88)
at Unknown.Ntj(History.java:68)
at Unknown.Vng(ValueChangeEvent.java:43)
at Unknown.FPe(History.java:77)
at Unknown.Qae(Application.java:273)
at Unknown.cbe(Application.java:269)
at Unknown.wke(TablesDataManager.java:43)
at Unknown.MWf(JsonRequestBuilder.java:164)
at Unknown.Pog(Request.java:227)
at Unknown.cpg(RequestBuilder.java:412)
at Unknown.anonymous(XMLHttpRequest.java:329)
at Unknown.Wag(Impl.java:299)
at Unknown.Zag(Impl.java:351)
at Unknown.anonymous(Impl.java:78)
Using GWT's com.google.gwt.core.server.StackTraceDeobfuscator and the
according symbol map, I was able to deobfuscate this to:
java.lang.Throwable: java.lang.StringIndexOutOfBoundsException: Index: 65,
Size: 4
at java.lang.Throwable.Throwable(Throwable.java:69)
at java.lang.Exception.Exception(Exception.java:36)
at
java.lang.RuntimeException.RuntimeException(RuntimeException.java:32)
at
java.lang.ArithmeticException.ArithmeticException(ArithmeticException.java:27)
at java.lang.StringBuilder.StringBuilder(StringBuilder.java:41)
at
javaemul.internal.InternalPreconditions.checkCriticalState(InternalPreconditions.java:379)
at
com.example.client.panels.SomePanel.someMethod(SomePanel.java:645)
at
com.example.client.NavigationManager.hideAllPopupMenus(NavigationManager.java:372)
at
com.example.client.NavigationManager.navigateAbsentRequests(NavigationManager.java:457)
at
com.example.client.panels.main.MainPanel$1.MainPanel$1(MainPanel.java:312)
at
com.google.gwt.event.logical.shared.ValueChangeEvent.ValueChangeEvent(ValueChangeEvent.java:100)
at
com.google.web.bindery.event.shared.SimpleEventBus.$doAddNow(SimpleEventBus.java:168)
at
com.google.gwt.event.shared.HandlerManager.$addHandler(HandlerManager.java:98)
at
com.google.gwt.user.client.History$HistoryEventSource.History$HistoryEventSource(History.java:62)
at
com.google.gwt.event.logical.shared.ValueChangeEvent.dispatch(ValueChangeEvent.java:127)
at
com.example.client.panels.main.MainPanel.$lambda$2(MainPanel.java:252)
at
com.example.client.Application.$successLogin(Application.java:220)
at
com.example.client.Application.$lambda$6$Type.Application$lambda$6$Type(Application.java:299)
at
com.example.client.client.datamanager.SomeDataManager.getSomeData(SomeDataManager.java:100)
at
com.example.jsonrpc.client.JsonRequestBuilder$2.JsonRequestBuilder$2(JsonRequestBuilder.java:377)
at com.google.gwt.http.client.Request.$cancel(Request.java:151)
at
com.google.gwt.http.client.RequestBuilder$1.RequestBuilder$1(RequestBuilder.java:408)
at Unknown.anonymous(XMLHttpRequest.java:329)
at com.google.gwt.core.client.impl.Impl.enter(Impl.java:313)
at com.google.gwt.core.client.impl.Impl.exit(Impl.java:373)
at Unknown.anonymous(Impl.java:78)
So the exception's message is still correct, but the line number where the
faulty line of code is present (195) is nowhere to be found in the
deobfuscated stacktrace. Also worth noting is that the exception caused by
the faulty line of code in SomePanel.java is reached after a few successive
method invocations, although the deobfuscated stacktrace doesn't include
those in the stack: I expected to have multiple stacktrace elements to
exist between the one mentioning SomePanel:someMethod and the one showing
the StringIndexOutOfBoundsException happening, but they simply aren't there
for some reason.
Can someone shed a light on why all of this is happening in the way it does?
Kind regards,
Nick
When the
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