Bug 29919 – HashTable.h has using directives for std::pair and std::make_pair

• Component: Web Template Framework
• Status: RESOLVED FIXED

[Kent Hansen]

Created attachment 40362 [details]
Proposed patch

The compiler complains about ambiguity in calls, apparently because there is a "using std::make_pair" in the WTF namespace (wtf/HashTraits.h) and Structure.cpp has both "using namespace std" and "using namespace WTF". Removing "using namespace std" makes it compile without any other changes needed.

Compiler output:

..\3rdparty\javascriptcore\JavaScriptCore\runtime\Structure.cpp(157) : error C2872: 'make_pair' : ambiguous symbol
could be ''unknown-type' make_pair'
or '..\3rdparty\javascriptcore\JavaScriptCore\wtf\HashTraits.h(32) : std::pair<_Ty1,_Ty2> std::make_pair(_Ty1,_Ty2)'
or 'make_pair'
..\3rdparty\javascriptcore\JavaScriptCore\runtime\Structure.cpp(397) : error C2872: 'make_pair' : ambiguous symbol
could be ''unknown-type' make_pair'
or '..\3rdparty\javascriptcore\JavaScriptCore\wtf\HashTraits.h(32) : std::pair<_Ty1,_Ty2> std::make_pair(_Ty1,_Ty2)'
or 'make_pair'
..\3rdparty\javascriptcore\JavaScriptCore\runtime\Structure.cpp(451) : error C2872: 'make_pair' : ambiguous symbol
could be ''unknown-type' make_pair'
or '..\3rdparty\javascriptcore\JavaScriptCore\wtf\HashTraits.h(32) : std::pair<_Ty1,_Ty2> std::make_pair(_Ty1,_Ty2)'
or 'make_pair'
..\3rdparty\javascriptcore\JavaScriptCore\runtime\Structure.cpp(875) : error C2872: 'make_pair' : ambiguous symbol
could be ''unknown-type' make_pair'
or '..\3rdparty\javascriptcore\JavaScriptCore\wtf\HashTraits.h(32) : std::pair<_Ty1,_Ty2> std::make_pair(_Ty1,_Ty2)'
or 'make_pair'
..\3rdparty\javascriptcore\JavaScriptCore\runtime\Structure.cpp(1037) : error C2668: 'std::max' : ambiguous call to overloaded function
C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\include\xutility(1242): could be 'const unsigned int &std::max(const unsigned int &,const unsigned int &)'
C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\include\xutility(1242): or 'const unsigned int &std::max(const unsigned int &,const unsigned int &)'
while trying to match the argument list '(unsigned int, unsigned int)'

[Darin Adler]

I think the better fix is to find a way remove the using std::make_pair from HashTraits.h. Generally we don't want to do using in headers.

[Darin Adler]

Is compiling in the two-versions-old version of Visual Studio a goal for the project?

[Eric Seidel (no email)]

Comment on attachment 40362 [details]
Proposed patch

Every patch requires a ChangeLog.  Also darin's comments above suggest this should not be landed as-is.
http://webkit.org/coding/contributing.html

[Caio Marcelo de Oliveira Filho]

Created attachment 144549 [details]
Patch

[Andreas Kling]

Comment on attachment 144549 [details]
Patch

Seems legit. r=me.
Probably wanna wait for EWSes just to be on the safe side.

[Build Bot]

Comment on attachment 144549 [details]
Patch

Attachment 144549 [details] did not pass mac-ews (mac):
Output: http://queues.webkit.org/results/12846500

[Caio Marcelo de Oliveira Filho]

Created attachment 144558 [details]
Patch

[Darin Adler]

Comment on attachment 144558 [details]
Patch

Normally it’s safer to do such patches in pairs. The first patch adds all the "std::" prefixes. Then the second one only removes the “using”. That way, if there is a problem and a roll-out is necessary, we only roll out a small change.

[Caio Marcelo de Oliveira Filho]

(In reply to comment #8)
> (From update of attachment 144558 [details])
> Normally it’s safer to do such patches in pairs. The first patch adds all the "std::" prefixes. Then the second one only removes the “using”. That way, if there is a problem and a roll-out is necessary, we only roll out a small change.

Thanks. Will land that way.

[Caio Marcelo de Oliveira Filho]

Committed r118934: <http://trac.webkit.org/changeset/118934>

[Caio Marcelo de Oliveira Filho]

Committed r118976: <http://trac.webkit.org/changeset/118976>