maintainer-feedback requested: [Bug 220188] devel/qt5-script: disable usage of c++1z for JavaScriptCore

[bugzilla-noreply at freebsd.org]

Dimitry Andric <dim at FreeBSD.org> has reassigned Bugzilla Automation
<bugzilla at FreeBSD.org>'s request for maintainer-feedback to kde at FreeBSD.org:
Bug 220188: devel/qt5-script: disable usage of c++1z for JavaScriptCore
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=220188



--- Description ---
Created attachment 183678
  --> https://bugs.freebsd.org/bugzilla/attachment.cgi?id=183678&action=edit
Use -std=c++14 for devel/qt5-script to avoid errors in JavaScriptCore

During an exp-run for the projects/clang500-import branch (bug 219139), it
turned out that devel/qt5-script does not build against libc++ 5.0.0 [1]:

In file included from
../3rdparty/javascriptcore/JavaScriptCore/pcre/pcre_exec.cpp:50:
In file included from
../3rdparty/javascriptcore/JavaScriptCore/wtf/Vector.h:27:
In file included from
../3rdparty/javascriptcore/JavaScriptCore/wtf/VectorTraits.h:24:
../3rdparty/javascriptcore/JavaScriptCore/wtf/OwnPtr.h:43:21: error: no
template named 'auto_ptr' in namespace 'std'
	OwnPtr(std::auto_ptr<ValueType> autoPtr) : m_ptr(autoPtr.release()) { }
	       ~~~~~^
../3rdparty/javascriptcore/JavaScriptCore/wtf/OwnPtr.h:61:25: error: no
template named 'auto_ptr' in namespace 'std'
	void adopt(std::auto_ptr<ValueType> autoPtr) { ASSERT(!autoPtr.get() ||
m_ptr != autoPtr.get()); deleteOwnedPtr(m_ptr); m_ptr = autoPtr.release(); }
		   ~~~~~^
In file included from
../3rdparty/javascriptcore/JavaScriptCore/pcre/pcre_exec.cpp:50:
In file included from
../3rdparty/javascriptcore/JavaScriptCore/wtf/Vector.h:27:
../3rdparty/javascriptcore/JavaScriptCore/wtf/VectorTraits.h:84:30: error: no
member named 'auto_ptr' in namespace 'std'
    struct VectorTraits<std::auto_ptr<P> > : SimpleClassVectorTraits { };
			~~~~~^
../3rdparty/javascriptcore/JavaScriptCore/wtf/VectorTraits.h:84:39: error: 'P'
does not refer to a value
    struct VectorTraits<std::auto_ptr<P> > : SimpleClassVectorTraits { };
				      ^
../3rdparty/javascriptcore/JavaScriptCore/wtf/VectorTraits.h:83:23: note:
declared here
    template<typename P>
		      ^
4 errors generated.

This is because devel/qmake and/or devel/qt5-buildtools have detected
-std=c++1z support, and are using it by default.  However, the JavaScriptCore
parts of qt5-script are from a third party, and this source is *not* C++1z
compatible.  For example, std::auto_ptr has long been deprecated, but is
actually removed from C++1z now.

I tried various methods of convincing qmake to use a lower C++ standard, and
the best I could come up with was adding a line:

QT_CONFIG -= c++1z

to src/3rdparty/javascriptcore/JavaScriptCore/JavaScriptCore.pri, as in the
attached patch.  If there is a better way, I would be glad to hear it. :)

[1]
http://package18.nyi.freebsd.org/data/headamd64PR219139-default/2017-05-22_13h0
1m42s/logs/errors/qt5-script-5.7.1.log