Bug 118274 – Fix maybe-uninitialized gcc 4.8 warning in HashTable.h

• Status: RESOLVED
• Resolution: INVALID
• Component: New Bugs

[Sergio Correia (qrwteyrutiyoup)]

[WTF]: Fix maybe-uninitialized gcc 4.8 warning in HashTable.h

[Sergio Correia (qrwteyrutiyoup)]

Created attachment 205855 [details]
Patch

[Sergio Correia (qrwteyrutiyoup)]

The actual warning:

In file included from /home/sergio/projects/webkitnix/Source/WebKit2/Platform/CoreIPC/MessageDecoder.h:30:0,
                 from /home/sergio/projects/webkitnix/Source/WebKit2/Platform/CoreIPC/Connection.h:32,
                 from /home/sergio/projects/webkitnix/Source/WebKit2/Platform/CoreIPC/Connection.cpp:27:
/home/sergio/projects/webkitnix/Source/WebKit2/Platform/CoreIPC/StringReference.h: In member function 'void WTF::HashTable<Key, Value, Extractor, HashFunctions, Traits, KeyTraits>::checkKey(const T&) [with HashTranslator = WTF::HashMapTranslator<WTF::HashMapValueTraits<WTF::HashTraits<std::pair<std::pair<CoreIPC::StringReference, CoreIPC::StringReference>, long unsigned int> >, WTF::HashTraits<WTF::OwnPtr<CoreIPC::MessageDecoder> > >, WTF::PairHash<std::pair<CoreIPC::StringReference, CoreIPC::StringReference>, long unsigned int> >; T = std::pair<std::pair<CoreIPC::StringReference, CoreIPC::StringReference>, long unsigned int>; Key = std::pair<std::pair<CoreIPC::StringReference, CoreIPC::StringReference>, long unsigned int>; Value = WTF::KeyValuePair<std::pair<std::pair<CoreIPC::StringReference, CoreIPC::StringReference>, long unsigned int>, WTF::OwnPtr<CoreIPC::MessageDecoder> >; Extractor = WTF::KeyValuePairKeyExtractor<WTF::KeyValuePair<std::pair<std::pair<CoreIPC::StringReference, CoreIPC::StringReference>, long unsigned int>, WTF::OwnPtr<CoreIPC::MessageDecoder> > >; HashFunctions = WTF::PairHash<std::pair<CoreIPC::StringReference, CoreIPC::StringReference>, long unsigned int>; Traits = WTF::HashMapValueTraits<WTF::HashTraits<std::pair<std::pair<CoreIPC::StringReference, CoreIPC::StringReference>, long unsigned int> >, WTF::HashTraits<WTF::OwnPtr<CoreIPC::MessageDecoder> > >; KeyTraits = WTF::HashTraits<std::pair<std::pair<CoreIPC::StringReference, CoreIPC::StringReference>, long unsigned int> >]':
/home/sergio/projects/webkitnix/Source/WebKit2/Platform/CoreIPC/StringReference.h:67:76: error: '*((void*)(& deletedValueBuffer)+16).CoreIPC::StringReference::m_data' may be used uninitialized in this function [-Werror=maybe-uninitialized]
In file included from /home/sergio/projects/webkitnix/Source/WTF/wtf/HashMap.h:24:0,
                 from /home/sergio/projects/webkitnix/Source/WebKit2/Platform/WorkQueue.h:38,
                 from /home/sergio/projects/webkitnix/Source/WebKit2/Platform/CoreIPC/Connection.h:35,
                 from /home/sergio/projects/webkitnix/Source/WebKit2/Platform/CoreIPC/Connection.cpp:27:
/home/sergio/projects/webkitnix/Source/WTF/wtf/HashTable.h:592:66: note: '*((void*)(& deletedValueBuffer)+16).CoreIPC::StringReference::m_data' was declared here
In file included from /home/sergio/projects/webkitnix/Source/WebKit2/Platform/CoreIPC/MessageDecoder.h:30:0,
                 from /home/sergio/projects/webkitnix/Source/WebKit2/Platform/CoreIPC/Connection.h:32,
                 from /home/sergio/projects/webkitnix/Source/WebKit2/Platform/CoreIPC/Connection.cpp:27:
/home/sergio/projects/webkitnix/Source/WebKit2/Platform/CoreIPC/StringReference.h:67:76: error: '*((void*)(& deletedValueBuffer)+16).CoreIPC::StringReference::m_size' may be used uninitialized in this function [-Werror=maybe-uninitialized]
In file included from /home/sergio/projects/webkitnix/Source/WTF/wtf/HashMap.h:24:0,
                 from /home/sergio/projects/webkitnix/Source/WebKit2/Platform/WorkQueue.h:38,
                 from /home/sergio/projects/webkitnix/Source/WebKit2/Platform/CoreIPC/Connection.h:35,
                 from /home/sergio/projects/webkitnix/Source/WebKit2/Platform/CoreIPC/Connection.cpp:27:
/home/sergio/projects/webkitnix/Source/WTF/wtf/HashTable.h:592:66: note: '*((void*)(& deletedValueBuffer)+16).CoreIPC::StringReference::m_size' was declared here
In file included from /home/sergio/projects/webkitnix/Source/WTF/wtf/HashTraits.h:24:0,
                 from /home/sergio/projects/webkitnix/Source/WebKit2/Platform/CoreIPC/StringReference.h:30,
                 from /home/sergio/projects/webkitnix/Source/WebKit2/Platform/CoreIPC/MessageDecoder.h:30,
                 from /home/sergio/projects/webkitnix/Source/WebKit2/Platform/CoreIPC/Connection.h:32,
                 from /home/sergio/projects/webkitnix/Source/WebKit2/Platform/CoreIPC/Connection.cpp:27:
/home/sergio/projects/webkitnix/Source/WTF/wtf/HashFunctions.h:157:115: error: 'deletedValueBuffer.std::pair<std::pair<CoreIPC::StringReference, CoreIPC::StringReference>, long unsigned int>::second' may be used uninitialized in this function [-Werror=maybe-uninitialized]

[Anders Carlsson]

Comment on attachment 205855 [details]
Patch

I don’t think we want to add an extra memset in order to silence a warning.

[Sergio Correia (qrwteyrutiyoup)]

(In reply to comment #3)
> (From update of attachment 205855 [details])
> I don’t think we want to add an extra memset in order to silence a warning.

Makes sense. I was wondering whether there was a way to build this without disabling the warning-as-error flag.

Thanks for the review.

[Anders Carlsson]

(In reply to comment #4)
> (In reply to comment #3)
> > (From update of attachment 205855 [details] [details])
> > I don’t think we want to add an extra memset in order to silence a warning.
> 
> Makes sense. I was wondering whether there was a way to build this without disabling the warning-as-error flag.
> 
> Thanks for the review.

I don’t think -wmaybe-uninitialized is a useful enough warning that it should be enabled by default.

[Sergio Correia (qrwteyrutiyoup)]

(In reply to comment #5)
> (In reply to comment #4)
> > (In reply to comment #3)
> > > (From update of attachment 205855 [details] [details] [details])
> > > I don’t think we want to add an extra memset in order to silence a warning.
> > 
> > Makes sense. I was wondering whether there was a way to build this without disabling the warning-as-error flag.
> > 
> > Thanks for the review.
> 
> I don’t think -wmaybe-uninitialized is a useful enough warning that it should be enabled by default.

Okay, I will disable it locally for now and close this bug as invalid.

[Darin Adler]

(In reply to comment #3)
> I don’t think we want to add an extra memset in order to silence a warning.

But this is assertion code, not production code. Maybe it’s OK given that?