developer-build fails for QSpecialIntegerBitfieldUnion

QtCore/private/qendian_p.h:179:40: error: '<unnamed>.QV4::CompiledData::RegExp::m_data.QSpecialIntegerBitfieldUnion<QLittleEndianStorageType<unsigned int>, QSpecialIntegerAccessor<QLittleEndianStorageType<unsigned int>, 0, 5, unsigned int>, QSpecialIntegerAccessor<QLittleEndianStorageType<unsigned int>, 5, 27, unsigned int> >::storage.QSpecialIntegerStorage<QLittleEndianStorageType<unsigned int> >::val' is used uninitialized [-Werror=uninitialized] 

| FAILED: src/qml/CMakeFiles/Qml.dir/compiler/qv4compiler.cpp.o
| /home/qt/work/build/build/tmp/work/cortexa57-poky-linux/qtdeclarative/6.4.0-r0/recipe-sysroot-native/usr/bin/aarch64-poky-linux/aarch64-poky-linux-g++ -DBUILDING_QT__ -DENABLE_ASSEMBLER_WX_EXCLUSIVE=1 -DENABLE_DFG_JIT=0 -DENABLE_DFG_JIT_UTILITY_METHODS=1 -DENABLE_JIT_CONSTANT_BLINDING=0 -DENABLE_LLINT=0 -DJS_EXPORT_PRIVATE="" -DNDEBUG -DQT_ASCII_CAST_WARNINGS -DQT_BUILDING_QT -DQT_BUILD_QML_LIB -DQT_CORE_LIB -DQT_DEPRECATED_WARNINGS -DQT_DEPRECATED_WARNINGS_SINCE=0x070000 -DQT_DISABLE_DEPRECATED_BEFORE=0x050000 -DQT_LEAN_HEADERS=1 -DQT_MOC_COMPAT -DQT_NETWORK_LIB -DQT_NO_CAST_TO_ASCII -DQT_NO_DEBUG -DQT_NO_EXCEPTIONS -DQT_NO_FOREACH -DQT_NO_INTEGER_EVENT_COORDINATES -DQT_NO_JAVA_STYLE_ITERATORS -DQT_NO_NARROWING_CONVERSIONS_IN_CONNECT -DQT_NO_URL_CAST_FROM_STRING -DQT_QMLINTEGRATION_LIB -DQT_STRICT_QLIST_ITERATORS -DQT_USE_QSTRINGBUILDER -DQml_EXPORTS -DWTFInvokeCrashHook=qmlWTFInvokeCrashHook -DWTFReportAssertionFailure=qmlWTFReportAssertionFailure 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-I/home/qt/work/build/build/tmp/work/cortexa57-poky-linux/qtdeclarative/6.4.0-r0/build/src/qml/memory -I/home/qt/work/build/build/tmp/work/cortexa57-poky-linux/qtdeclarative/6.4.0-r0/build/src/qml/qmldirparser -I/home/qt/work/build/build/tmp/work/cortexa57-poky-linux/qtdeclarative/6.4.0-r0/git/src/qml/../3rdparty/masm -I/home/qt/work/build/build/tmp/work/cortexa57-poky-linux/qtdeclarative/6.4.0-r0/git/src/qml/../3rdparty/masm/assembler -I/home/qt/work/build/build/tmp/work/cortexa57-poky-linux/qtdeclarative/6.4.0-r0/git/src/qml/../3rdparty/masm/disassembler -I/home/qt/work/build/build/tmp/work/cortexa57-poky-linux/qtdeclarative/6.4.0-r0/git/src/qml/../3rdparty/masm/disassembler/udis86 -I/home/qt/work/build/build/tmp/work/cortexa57-poky-linux/qtdeclarative/6.4.0-r0/git/src/qml/../3rdparty/masm/jit -I/home/qt/work/build/build/tmp/work/cortexa57-poky-linux/qtdeclarative/6.4.0-r0/git/src/qml/../3rdparty/masm/runtime -I/home/qt/work/build/build/tmp/work/cortexa57-poky-linux/qtdeclarative/6.4.0-r0/git/src/qml/../3rdparty/masm/stubs -I/home/qt/work/build/build/tmp/work/cortexa57-poky-linux/qtdeclarative/6.4.0-r0/git/src/qml/../3rdparty/masm/stubs/runtime -I/home/qt/work/build/build/tmp/work/cortexa57-poky-linux/qtdeclarative/6.4.0-r0/git/src/qml/../3rdparty/masm/stubs/wtf -I/home/qt/work/build/build/tmp/work/cortexa57-poky-linux/qtdeclarative/6.4.0-r0/git/src/qml/../3rdparty/masm/wtf -I/home/qt/work/build/build/tmp/work/cortexa57-poky-linux/qtdeclarative/6.4.0-r0/git/src/qml/.generated -I/home/qt/work/build/build/tmp/work/cortexa57-poky-linux/qtdeclarative/6.4.0-r0/git/src/qml/compiler -I/home/qt/work/build/build/tmp/work/cortexa57-poky-linux/qtdeclarative/6.4.0-r0/git/src/qml/debugger -I/home/qt/work/build/build/tmp/work/cortexa57-poky-linux/qtdeclarative/6.4.0-r0/git/src/qml/jsruntime -I/home/qt/work/build/build/tmp/work/cortexa57-poky-linux/qtdeclarative/6.4.0-r0/git/src/qml/memory -I/home/qt/work/build/build/tmp/work/cortexa57-poky-linux/qtdeclarative/6.4.0-r0/git/src/qml/qmldirparser -I/home/qt/work/build/build/tmp/work/cortexa57-poky-linux/qtdeclarative/6.4.0-r0/build/include/QtQml/6.4.0 -I/home/qt/work/build/build/tmp/work/cortexa57-poky-linux/qtdeclarative/6.4.0-r0/build/include/QtQml/6.4.0/QtQml -I/home/qt/work/build/build/tmp/work/cortexa57-poky-linux/qtdeclarative/6.4.0-r0/recipe-sysroot/usr/include/QtCore/6.4.0 -I/home/qt/work/build/build/tmp/work/cortexa57-poky-linux/qtdeclarative/6.4.0-r0/recipe-sysroot/usr/include/QtCore/6.4.0/QtCore -I/home/qt/work/build/build/tmp/work/cortexa57-poky-linux/qtdeclarative/6.4.0-r0/recipe-sysroot/usr/include/QtCore -I/home/qt/work/build/build/tmp/work/cortexa57-poky-linux/qtdeclarative/6.4.0-r0/recipe-sysroot/usr/lib/mkspecs/linux-g++ -I/home/qt/work/build/build/tmp/work/cortexa57-poky-linux/qtdeclarative/6.4.0-r0/build/include/QtQmlIntegration -I/home/qt/work/build/build/tmp/work/cortexa57-poky-linux/qtdeclarative/6.4.0-r0/git/src/qmlintegration -I/home/qt/work/build/build/tmp/work/cortexa57-poky-linux/qtdeclarative/6.4.0-r0/build/src/qmlintegration -I/home/qt/work/build/build/tmp/work/cortexa57-poky-linux/qtdeclarative/6.4.0-r0/recipe-sysroot/usr/include/QtNetwork -I/home/qt/work/build/build/tmp/work/cortexa57-poky-linux/qtdeclarative/6.4.0-r0/build/src/qml/.generated/release -I/home/qt/work/build/build/tmp/work/cortexa57-poky-linux/qtdeclarative/6.4.0-r0/build/src/qml/jit -I/home/qt/work/build/build/tmp/work/cortexa57-poky-linux/qtdeclarative/6.4.0-r0/git/src/qml/jit -I/home/qt/work/build/build/tmp/work/cortexa57-poky-linux/qtdeclarative/6.4.0-r0/git/src/qml/animations -mcpu=cortex-a57 -march=armv8-a+crc -fstack-protector-strong  -O2 -D_FORTIFY_SOURCE=2 -Wformat -Wformat-security -Werror=format-security  --sysroot=/home/qt/work/build/build/tmp/work/cortexa57-poky-linux/qtdeclarative/6.4.0-r0/recipe-sysroot  -O2 -pipe -g -feliminate-unused-debug-types -fmacro-prefix-map=/home/qt/work/build/build/tmp/work/cortexa57-poky-linux/qtdeclarative/6.4.0-r0=/usr/src/debug/qtdeclarative/6.4.0-r0                      -fdebug-prefix-map=/home/qt/work/build/build/tmp/work/cortexa57-poky-linux/qtdeclarative/6.4.0-r0=/usr/src/debug/qtdeclarative/6.4.0-r0                      -fdebug-prefix-map=/home/qt/work/build/build/tmp/work/cortexa57-poky-linux/qtdeclarative/6.4.0-r0/recipe-sysroot=                      -fdebug-prefix-map=/home/qt/work/build/build/tmp/work/cortexa57-poky-linux/qtdeclarative/6.4.0-r0/recipe-sysroot-native=  -fvisibility-inlines-hidden -DNDEBUG -O2 -fPIC -fvisibility=hidden -fvisibility-inlines-hidden -Wall -Wextra -fno-exceptions -Werror -Wno-error=cpp -Wno-error=deprecated-declarations -Wno-error=strict-overflow -Wno-error=implicit-fallthrough -Wno-error=deprecated-copy -Wno-error=redundant-move -Wno-error=init-list-lifetime -Wno-error=format-overflow -Wno-error=stringop-overflow -Wno-error=deprecated-enum-enum-conversion -Wno-error=deprecated-enum-float-conversion -Wsuggest-override -std=c++17 -MD -MT src/qml/CMakeFiles/Qml.dir/compiler/qv4compiler.cpp.o -MF src/qml/CMakeFiles/Qml.dir/compiler/qv4compiler.cpp.o.d -o src/qml/CMakeFiles/Qml.dir/compiler/qv4compiler.cpp.o -c /home/qt/work/build/build/tmp/work/cortexa57-poky-linux/qtdeclarative/6.4.0-r0/git/src/qml/compiler/qv4compiler.cpp
| In file included from /home/qt/work/build/build/tmp/work/cortexa57-poky-linux/qtdeclarative/6.4.0-r0/build/include/QtQml/6.4.0/QtQml/private/../../../../../../git/src/qml/common/qv4compileddata_p.h:68,
|                  from /home/qt/work/build/build/tmp/work/cortexa57-poky-linux/qtdeclarative/6.4.0-r0/build/include/QtQml/6.4.0/QtQml/private/qv4compileddata_p.h:1,
|                  from /home/qt/work/build/build/tmp/work/cortexa57-poky-linux/qtdeclarative/6.4.0-r0/git/src/qml/compiler/qv4compiler_p.h:58,
|                  from /home/qt/work/build/build/tmp/work/cortexa57-poky-linux/qtdeclarative/6.4.0-r0/git/src/qml/compiler/qv4compiler.cpp:41:
| In member function 'QSpecialIntegerAccessor<S, pos, width, T>& QSpecialIntegerAccessor<S, pos, width, T>::operator=(QSpecialIntegerAccessor<S, pos, width, T>::Type) [with S = QLittleEndianStorageType<unsigned int>; int pos = 0; int width = 5; T = unsigned int]',
|     inlined from 'void QSpecialIntegerBitfieldUnion<S, Accessors>::set(typename A::Type) [with A = QSpecialIntegerAccessor<QLittleEndianStorageType<unsigned int>, 0, 5, unsigned int>; S = QLittleEndianStorageType<unsigned int>; Accessors = {QSpecialIntegerAccessor<QLittleEndianStorageType<unsigned int>, 0, 5, unsigned int>, QSpecialIntegerAccessor<QLittleEndianStorageType<unsigned int>, 5, 27, unsigned int>}]' at /home/qt/work/build/build/tmp/work/cortexa57-poky-linux/qtdeclarative/6.4.0-r0/recipe-sysroot/usr/include/QtCore/6.4.0/QtCore/private/qendian_p.h:214:21,
|     inlined from 'QV4::CompiledData::RegExp::RegExp(quint32, quint32)' at /home/qt/work/build/build/tmp/work/cortexa57-poky-linux/qtdeclarative/6.4.0-r0/build/include/QtQml/6.4.0/QtQml/private/../../../../../../git/src/qml/common/qv4compileddata_p.h:187:31,
|     inlined from 'int QV4::Compiler::JSUnitGenerator::registerRegExp(QQmlJS::AST::RegExpLiteral*)' at /home/qt/work/build/build/tmp/work/cortexa57-poky-linux/qtdeclarative/6.4.0-r0/git/src/qml/compiler/qv4compiler.cpp:198:34:
| /home/qt/work/build/build/tmp/work/cortexa57-poky-linux/qtdeclarative/6.4.0-r0/recipe-sysroot/usr/include/QtCore/6.4.0/QtCore/private/qendian_p.h:179:40: error: '<unnamed>.QV4::CompiledData::RegExp::m_data.QSpecialIntegerBitfieldUnion<QLittleEndianStorageType<unsigned int>, QSpecialIntegerAccessor<QLittleEndianStorageType<unsigned int>, 0, 5, unsigned int>, QSpecialIntegerAccessor<QLittleEndianStorageType<unsigned int>, 5, 27, unsigned int> >::storage.QSpecialIntegerStorage<QLittleEndianStorageType<unsigned int> >::val' is used uninitialized [-Werror=uninitialized]
|   179 |         UnsignedType i = S::fromSpecial(storage->val);
|       |                          ~~~~~~~~~~~~~~^~~~~~~~~~~~~~
| /home/qt/work/build/build/tmp/work/cortexa57-poky-linux/qtdeclarative/6.4.0-r0/git/src/qml/compiler/qv4compiler.cpp: In member function 'int QV4::Compiler::JSUnitGenerator::registerRegExp(QQmlJS::AST::RegExpLiteral*)':
| /home/qt/work/build/build/tmp/work/cortexa57-poky-linux/qtdeclarative/6.4.0-r0/git/src/qml/compiler/qv4compiler.cpp:198:90: note: '<anonymous>' declared here
|   198 |     regexps.append(CompiledData::RegExp(flags, registerString(regexp->pattern.toString())));
|       |                                                                                          ^
| cc1plus: all warnings being treated as errors