Bug 171010 – Vector.h: error: 'auto' not allowed in lambda parameter

• Component: Web Template Framework
• Status: RESOLVED FIXED

[David Kilzer (:ddkilzer)]

In file included from $(INSTALL_ROOT)/System/Library/Frameworks/WebKit.framework/PrivateHeaders/EnvironmentUtilities.h:29:
In file included from $(SDKROOT)/usr/local/include/wtf/text/WTFString.h:30:
In file included from $(SDKROOT)/usr/local/include/wtf/text/StringImpl.h:35:
$(SDKROOT)/usr/local/include/wtf/Vector.h:1526:47: error: 'auto' not allowed in lambda parameter
    return removeRepeatedElements(vector, [] (auto& a, auto& b) { return a == b; });
                                              ^~~~
$(SDKROOT)/usr/local/include/wtf/Vector.h:1526:56: error: 'auto' not allowed in lambda parameter
    return removeRepeatedElements(vector, [] (auto& a, auto& b) { return a == b; });
                                                       ^~~~
2 errors generated.

This code was committed in Bug 170102, but was triggered by a change in Bug 170994 that exposed EnvironmentUtilities.h as a private header in WebKit.framework.

[David Kilzer (:ddkilzer)]

<rdar://problem/31716076>

[David Kilzer (:ddkilzer)]

Created attachment 307509 [details]
Patch

[Build Bot]

Attachment 307509 [details] did not pass style-queue:


ERROR: Source/WTF/wtf/Vector.h:1526:  More than one command on the same line  [whitespace/newline] [4]
Total errors found: 1 in 2 files


If any of these errors are false positives, please file a bug against check-webkit-style.

[Saam Barati]

Comment on attachment 307509 [details]
Patch

r=me

[WebKit Commit Bot]

Comment on attachment 307509 [details]
Patch

Clearing flags on attachment: 307509

Committed r215538: <http://trac.webkit.org/changeset/215538>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.

[Chris Dumez]

Comment on attachment 307509 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=307509&action=review

> Source/WTF/ChangeLog:3
> +        Vector.h: error: 'auto' not allowed in lambda parameter

It is allowed with c++14. The issue is that the project in question is building with c++11 support instead of c++14. I think we should fix this instead.

[Chris Dumez]

Comment on attachment 307509 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=307509&action=review

>> Source/WTF/ChangeLog:3
>> +        Vector.h: error: 'auto' not allowed in lambda parameter
> 
> It is allowed with c++14. The issue is that the project in question is building with c++11 support instead of c++14. I think we should fix this instead.

Source/WebKit/mac/Configurations/WebKitLegacy.xcconfig:OTHER_TAPI_FLAGS[sdk=iphone*] = -x objective-c++ -std=c++11 -fno-rtti;

We likely want c++14 here.

[Brent Fulgham]

Comment on attachment 307509 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=307509&action=review

>>> Source/WTF/ChangeLog:3
>>> +        Vector.h: error: 'auto' not allowed in lambda parameter
>> 
>> It is allowed with c++14. The issue is that the project in question is building with c++11 support instead of c++14. I think we should fix this instead.
> 
> Source/WebKit/mac/Configurations/WebKitLegacy.xcconfig:OTHER_TAPI_FLAGS[sdk=iphone*] = -x objective-c++ -std=c++11 -fno-rtti;
> 
> We likely want c++14 here.

I think this also broke the Windows build, so we may want to be careful.

[Chris Dumez]

Can we roll this out after https://trac.webkit.org/changeset/215560/webkit ?

[Brent Fulgham]

(In reply to Chris Dumez from comment #10)
> Can we roll this out after https://trac.webkit.org/changeset/215560/webkit ?

It also breaks Windows, so I don't think so.

[Brent Fulgham]

(In reply to Chris Dumez from comment #10)
> Can we roll this out after https://trac.webkit.org/changeset/215560/webkit ?

I think we can roll this workaround out once we update our Windows build infrastructure to Visual Studio 2017.

[Brent Fulgham]

(In reply to Brent Fulgham from comment #12)
> (In reply to Chris Dumez from comment #10)
> > Can we roll this out after https://trac.webkit.org/changeset/215560/webkit ?
> 
> I think we can roll this workaround out once we update our Windows build
> infrastructure to Visual Studio 2017.

I'm wrong!

I just rolled this patch out locally, and was able to build WebKit without trouble on Windows. So it looks like VS2015 Update 3's C++14 support is sufficient here.

[David Kilzer (:ddkilzer)]

(In reply to Brent Fulgham from comment #13)
> (In reply to Brent Fulgham from comment #12)
> > (In reply to Chris Dumez from comment #10)
> > > Can we roll this out after https://trac.webkit.org/changeset/215560/webkit ?
> > 
> > I think we can roll this workaround out once we update our Windows build
> > infrastructure to Visual Studio 2017.
> 
> I'm wrong!
> 
> I just rolled this patch out locally, and was able to build WebKit without
> trouble on Windows. So it looks like VS2015 Update 3's C++14 support is
> sufficient here.

Based on Source/WebKit2/Configurations/Base.xcconfig, we can't roll out this change until we switch to c++14 (or gnu++14) for this:

OTHER_TAPI_FLAGS[sdk=iphone*] = -x objective-c++ -std=c++11 -fno-rtti;

[Alexey Proskuryakov]

Ideally, we would not make any C++ headers WebKit SPI, and then we won't need to worry about InstallAPI here.