[Webkit-unassigned] [Bug 13434] New: gcc warning in JavaScriptCore/wtf

bugzilla-daemon at webkit.org bugzilla-daemon at webkit.org
Sat Apr 21 05:23:47 PDT 2007 

http://bugs.webkit.org/show_bug.cgi?id=13434

           Summary: gcc warning in JavaScriptCore/wtf
           Product: WebKit
           Version: 522+ (nightly)
          Platform: PC
        OS/Version: All
            Status: UNCONFIRMED
          Severity: Normal
          Priority: P2
         Component: JavaScriptCore
        AssignedTo: webkit-unassigned at lists.webkit.org
        ReportedBy: alp at atoker.com


This compiler warning is issued by gcc 4.1.2 (which is apparently more recent
than what's used by Apple). It was noticed when building the "gdk" port.

bdash points out that "according to the man page, the warning will only be
emitted in unsafe cases. there's a separate flag to turn on warning in all
cases, even those which are potentially safe"

So it's possible that gcc is now good enough to identify more "unsafe"
conditions, in which case the bug should be fixed, or it might be a regression
in gcc's detection of unsafe conditions, in which case it might be worth
considering suppressing the warning. I leave it to someone familiar with the
code to determine this.

I include the flags we use in the gdk port for reference.


g++ -c -o obj-gnu/webcore_gdk_RenderApplet.o -I../../../JavaScriptCore -I../..
-I../../bindings/js -I../../bridge -I../../css -I../../DerivedSources/WebCore
-I../../dom -I../../editing -I../../ForwardingHeaders/kjs -I../../history
-I../../html -I../../include -I../../loader -I../../loader/gdk
-I../../loader/icon -I../../page -I../../platform -I../../platform/graphics
-I../../platform/graphics/gdk -I../../platform/image-decoders
-I../../platform/image-decoders/bmp -I../../platform/image-decoders/gif
-I../../platform/image-decoders/ico -I../../platform/image-decoders/jpeg
-I../../platform/image-decoders/png -I../../platform/image-decoders/xbm
-I../../platform/image-decoders/zlib -I../../platform/network
-I../../platform/network/gdk -I../../rendering -I../../xml -DENABLE_XSLT=1
-DLINUX -DUSE_CONSERVATIVE_GC=0 -DHAVE_FUNC_ISNAN -D_THREAD_SAFE -pthread -g
-I../../platform/gdk -I../../platform/network/gdk -DBUILDING_GDK__
-DBUILDING_CAIRO__ -Iplatform/gdk -Iplatform/graphics/cairo -DENABLE_XPATH
-I/usr/include/libxml2 -I/usr/include/libxml2 -g -Wall -O2 
-I/usr/include/freetype2    -I/usr/include/gtk-2.0 -I/usr/lib/gtk-2.0/include
-I/usr/include/atk-1.0 -I/usr/include/cairo -I/usr/include/pango-1.0
-I/usr/include/glib-2.0 -I/usr/lib/glib-2.0/include -I/usr/include/freetype2
-I/usr/include/libpng12    -I/usr/include/cairo -I/usr/include/freetype2
-I/usr/include/libpng12    -fPIC -DPIC -fno-rtti -fno-exceptions  
-MTobj-gnu/webcore_gdk_RenderApplet.o -MF`echo
obj-gnu/webcore_gdk_RenderApplet.o | sed -e 's,\.o$,.d,'` -MD
../../rendering/RenderApplet.cpp
../../../JavaScriptCore/wtf/HashTable.h: In static member function 'static void
WTF::RefCounter<WTF::PairBaseHashTraits<FirstTraits, SecondTraits>,
ValueStorageTraits>::deref(const typename ValueStorageTraits::TraitType&) [with
FirstTraits = WTF::HashTraits<WebCore::String>, SecondTraits =
WTF::HashTraits<WebCore::String>, ValueStorageTraits =
WTF::PairHashTraits<WTF::HashTraits<WebCore::StringImpl*>, WTF::HashTraits<int>
>]':
../../../JavaScriptCore/wtf/HashMap.h:291:   instantiated from 'void
WTF::HashMap<KeyArg, MappedArg, HashArg, KeyTraitsArg,
MappedTraitsArg>::remove(WTF::HashTableIteratorAdapter<WTF::HashTable<typename
WTF::HashKeyStorageTraits<HashArg, KeyTraitsArg>::Traits::TraitType, typename
WTF::PairHashTraits<typename WTF::HashKeyStorageTraits<HashArg,
KeyTraitsArg>::Traits, typename MappedTraitsArg::StorageTraits>::TraitType,
WTF::PairFirstExtractor<typename WTF::PairHashTraits<typename
WTF::HashKeyStorageTraits<HashArg, KeyTraitsArg>::Traits, typename
MappedTraitsArg::StorageTraits>::TraitType>, typename
WTF::HashKeyStorageTraits<HashArg, KeyTraitsArg>::Hash,
WTF::PairHashTraits<typename WTF::HashKeyStorageTraits<HashArg,
KeyTraitsArg>::Traits, typename MappedTraitsArg::StorageTraits>, typename
WTF::HashKeyStorageTraits<HashArg, KeyTraitsArg>::Traits>, typename
WTF::PairBaseHashTraits<KeyTraitsArg, MappedTraitsArg>::TraitType>) [with
KeyArg = WebCore::String, MappedArg = WebCore::String, HashArg =
WTF::CaseInsensitiveHash<WebCore::String>, KeyTraitsArg =
WTF::HashTraits<WebCore::String>, MappedTraitsArg =
WTF::HashTraits<WebCore::String>]'
../../../JavaScriptCore/wtf/HashMap.h:298:   instantiated from 'void
WTF::HashMap<KeyArg, MappedArg, HashArg, KeyTraitsArg,
MappedTraitsArg>::remove(const typename KeyTraitsArg::TraitType&) [with KeyArg
= WebCore::String, MappedArg = WebCore::String, HashArg =
WTF::CaseInsensitiveHash<WebCore::String>, KeyTraitsArg =
WTF::HashTraits<WebCore::String>, MappedTraitsArg =
WTF::HashTraits<WebCore::String>]'
../../platform/network/ResourceRequest.h:132:   instantiated from here
../../../JavaScriptCore/wtf/HashTable.h:895: warning: dereferencing type-punned
pointer will break strict-aliasing rules
../../../JavaScriptCore/wtf/HashMap.h: In static member function 'static void
WTF::HashMapTranslator<false, ValueType, ValueStorageTraits,
HashFunctions>::translate(typename ValueStorageTraits::TraitType&, const
typename ValueType::first_type&, const typename ValueType::second_type&,
unsigned int) [with ValueType = std::pair<WebCore::String, WebCore::String>,
ValueStorageTraits = WTF::PairHashTraits<WTF::HashTraits<WebCore::StringImpl*>,
WTF::HashTraits<int> >, HashFunctions = WTF::StrHash<WebCore::String>]':
../../../JavaScriptCore/wtf/HashTable.h:443:   instantiated from
'std::pair<typename WTF::HashTable<Key, Value, Extractor, HashFunctions,
Traits, KeyTraits>::iterator, bool> WTF::HashTable<Key, Value, Extractor,
HashFunctions, Traits, KeyTraits>::add(const T&, const Extra&) [with T =
WebCore::String, Extra = WebCore::String, HashTranslator =
WTF::HashMapTranslator<false, std::pair<WebCore::String, WebCore::String>,
WTF::PairHashTraits<WTF::HashTraits<WebCore::StringImpl*>, WTF::HashTraits<int>
>, WTF::StrHash<WebCore::String> >, Key = WebCore::StringImpl*, Value =
std::pair<WebCore::StringImpl*, int>, Extractor =
WTF::PairFirstExtractor<std::pair<WebCore::StringImpl*, int> >, HashFunctions =
WTF::StrHash<WebCore::StringImpl*>, Traits =
WTF::PairHashTraits<WTF::HashTraits<WebCore::StringImpl*>, WTF::HashTraits<int>
>, KeyTraits = WTF::HashTraits<WebCore::StringImpl*>]'
../../../JavaScriptCore/wtf/HashMap.h:255:   instantiated from
'std::pair<typename WTF::HashMap<KeyArg, MappedArg, HashArg, KeyTraitsArg,
MappedTraitsArg>::iterator, bool> WTF::HashMap<KeyArg, MappedArg, HashArg,
KeyTraitsArg, MappedTraitsArg>::inlineAdd(const typename
KeyTraitsArg::TraitType&, const typename MappedTraitsArg::TraitType&) [with
KeyArg = WebCore::String, MappedArg = WebCore::String, HashArg =
WTF::StrHash<WebCore::String>, KeyTraitsArg = WTF::HashTraits<WebCore::String>,
MappedTraitsArg = WTF::HashTraits<WebCore::String>]'
../../../JavaScriptCore/wtf/HashMap.h:262:   instantiated from
'std::pair<typename WTF::HashMap<KeyArg, MappedArg, HashArg, KeyTraitsArg,
MappedTraitsArg>::iterator, bool> WTF::HashMap<KeyArg, MappedArg, HashArg,
KeyTraitsArg, MappedTraitsArg>::set(const typename KeyTraitsArg::TraitType&,
const typename MappedTraitsArg::TraitType&) [with KeyArg = WebCore::String,
MappedArg = WebCore::String, HashArg = WTF::StrHash<WebCore::String>,
KeyTraitsArg = WTF::HashTraits<WebCore::String>, MappedTraitsArg =
WTF::HashTraits<WebCore::String>]'
../../rendering/RenderApplet.cpp:86:   instantiated from here
../../../JavaScriptCore/wtf/HashMap.h:147: warning: dereferencing type-punned
pointer will break strict-aliasing rules
../../../JavaScriptCore/wtf/HashTable.h: In static member function 'static void
WTF::RefCounter<WTF::PairBaseHashTraits<FirstTraits, SecondTraits>,
ValueStorageTraits>::ref(const typename ValueStorageTraits::TraitType&) [with
FirstTraits = WTF::HashTraits<WebCore::String>, SecondTraits =
WTF::HashTraits<WebCore::String>, ValueStorageTraits =
WTF::PairHashTraits<WTF::HashTraits<WebCore::StringImpl*>, WTF::HashTraits<int>
>]':
../../../JavaScriptCore/wtf/HashTable.h:922:   instantiated from 'static void
WTF::HashTableRefCounterBase<true, HashTableType,
ValueTraits>::refAll(HashTableType&) [with HashTableType =
WTF::HashTable<WebCore::StringImpl*, std::pair<WebCore::StringImpl*, int>,
WTF::PairFirstExtractor<std::pair<WebCore::StringImpl*, int> >,
WTF::StrHash<WebCore::StringImpl*>,
WTF::PairHashTraits<WTF::HashTraits<WebCore::StringImpl*>, WTF::HashTraits<int>
>, WTF::HashTraits<WebCore::StringImpl*> >, ValueTraits =
WTF::PairBaseHashTraits<WTF::HashTraits<WebCore::String>,
WTF::HashTraits<WebCore::String> >]'
../../../JavaScriptCore/wtf/HashTable.h:936:   instantiated from 'static void
WTF::HashTableRefCounter<HashTableType, ValueTraits>::refAll(HashTableType&)
[with HashTableType = WTF::HashTable<WebCore::StringImpl*,
std::pair<WebCore::StringImpl*, int>,
WTF::PairFirstExtractor<std::pair<WebCore::StringImpl*, int> >,
WTF::StrHash<WebCore::StringImpl*>,
WTF::PairHashTraits<WTF::HashTraits<WebCore::StringImpl*>, WTF::HashTraits<int>
>, WTF::HashTraits<WebCore::StringImpl*> >, ValueTraits =
WTF::PairBaseHashTraits<WTF::HashTraits<WebCore::String>,
WTF::HashTraits<WebCore::String> >]'
../../../JavaScriptCore/wtf/HashMap.h:154:   instantiated from 'void
WTF::HashMap<KeyArg, MappedArg, HashArg, KeyTraitsArg,
MappedTraitsArg>::refAll() [with KeyArg = WebCore::String, MappedArg =
WebCore::String, HashArg = WTF::StrHash<WebCore::String>, KeyTraitsArg =
WTF::HashTraits<WebCore::String>, MappedTraitsArg =
WTF::HashTraits<WebCore::String>]'
../../../JavaScriptCore/wtf/HashMap.h:172:   instantiated from
'WTF::HashMap<KeyArg, MappedArg, HashArg, KeyTraitsArg,
MappedTraitsArg>::HashMap(const WTF::HashMap<KeyArg, MappedArg, HashArg,
KeyTraitsArg, MappedTraitsArg>&) [with KeyArg = WebCore::String, MappedArg =
WebCore::String, HashArg = WTF::StrHash<WebCore::String>, KeyTraitsArg =
WTF::HashTraits<WebCore::String>, MappedTraitsArg =
WTF::HashTraits<WebCore::String>]'
../../rendering/RenderApplet.cpp:41:   instantiated from here
../../../JavaScriptCore/wtf/HashTable.h:891: warning: dereferencing type-punned
pointer will break strict-aliasing rules


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