[MacPorts] #55639: QtCore unusable with Apple LLVM version 9.0.0

[MacPorts]

#55639: QtCore unusable with Apple LLVM version 9.0.0
----------------------+---------------------
 Reporter:  janstary  |      Owner:
     Type:  defect    |     Status:  new
 Priority:  Normal    |  Milestone:
Component:  ports     |    Version:  2.4.99
 Keywords:            |       Port:  bitcoin
----------------------+---------------------
 Building bitcoin +gui fails for me on 10.13.2 with XCode 9.2
 The log (attached) says

 {{{
 :info:build /usr/bin/clang++ -std=c++11 -DHAVE_CONFIG_H -I.
 -I../src/config   -I. -I./obj -I/opt/local/include/db48/
 -DBOOST_SP_USE_STD_ATOMIC -DBOOST_AC_USE_STD_ATOMIC -pthread
 -I/opt/local/include -I./leveldb/include -I./leveldb/helpers/memenv
 -I./secp256k1/include -I./univalue/include -I./qt -I./qt -I./qt/forms
 -I./qt/forms -DQT_NO_KEYWORDS -I/opt/local/libexec/qt5/include/QtNetwork
 -I/opt/local/libexec/qt5/include
 -I/opt/local/libexec/qt5/include/QtWidgets
 -I/opt/local/libexec/qt5/include -I/opt/local/libexec/qt5/include/QtGui
 -I/opt/local/libexec/qt5/include -I/opt/local/libexec/qt5/include/QtCore
 -I/opt/local/libexec/qt5/include -D_THREAD_SAFE  -I/opt/local/include
 -DHAVE_BUILD_INFO -D__STDC_FORMAT_MACROS -isystem /opt/local/include
 -I/opt/local/include/db48 -DMAC_OSX  -Werror=vla  -pipe -Os -stdlib=libc++
 -arch x86_64 -MT qt/qt_bitcoin_qt-bitcoin.o -MD -MP -MF qt/.deps
 /qt_bitcoin_qt-bitcoin.Tpo -c -o qt/qt_bitcoin_qt-bitcoin.o `test -f
 'qt/bitcoin.cpp' || echo './'`qt/bitcoin.cpp
 :info:build
 /opt/local/libexec/qt5/include/QtCore/qcompilerdetection.h:567:6: error:
 Qt requires a C++11 compiler and yours does not seem to be that.
 :info:build #    error Qt requires a C++11 compiler and yours does not
 seem to be that.
 }}}

 Looking at `QtCore/qcompilerdetection.h`:

 {{{
 #ifdef __cplusplus
 #  if __cplusplus < 201103L && !(defined(Q_CC_MSVC) && Q_CC_MSVC >= 1800)
 #    error Qt requires a C++11 compiler and yours does not seem to be
 that.
 #  endif
 #endif
 }}}

 My compiler is

 {{{
 $ c++ -v
 Apple LLVM version 9.0.0 (clang-900.0.39.2)
 Target: x86_64-apple-darwin17.3.0
 Thread model: posix
 InstalledDir:
 /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin
 }}}

 which is

 {{{
 $ clang++ -v
 Apple LLVM version 9.0.0 (clang-900.0.39.2)
 Target: x86_64-apple-darwin17.3.0
 Thread model: posix
 InstalledDir:
 /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin
 }}}

 which is

 {{{
 $ g++ -v
 Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr
 --with-gxx-include-dir=/usr/include/c++/4.2.1
 Apple LLVM version 9.0.0 (clang-900.0.39.2)
 Target: x86_64-apple-darwin17.3.0
 Thread model: posix
 InstalledDir:
 /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin
 }}}

 under whichever name.

 I am putting 'bitcoin' as the port here, because that's where it bit me,
 but perhaps this is a QtCore bug, or something more general with compiler
 detection.

--
Ticket URL: <https://trac.macports.org/ticket/55639>
MacPorts <https://www.macports.org/>
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