title: How to install qt6 with Homerew on macOS High Sierra 10.13.6?
body: <p>Although High Sierra is no longer supported by Homebrew, but I need to install qt@6 formula as a dependency for other formulas. So I tried to install it this way:</p>
  <pre><code>$ brew install qt
  </code></pre>
  <p>An error is occurred after a long time of compilation. I also found these errors in <strong>~/Library/Logs/Homebrew/qt/02.cmake</strong>:</p>
  <pre><code>FAILED: qtbase/src/tools/bootstrap/CMakeFiles/Bootstrap.dir/__/__/corelib/kernel/qmetatype.cpp.o /usr/local/Homebrew/Library/Homebrew/shims/mac/super/clang++
  -DGL_SILENCE_DEPRECATION -DHAVE_CONFIG_H -DQT_BOOTSTRAPPED -DQT_NO_CAST_FROM_ASCII -DQT_NO_CAST_TO_ASCII -DQT_NO_DEBUG -DQT_NO_FOREACH -DQT_USE_QSTRINGBUILDER -DQT_VERSION_MAJOR=6 -DQT_VERSION_MINOR=2 -DQT_VERSION_PATCH=1 -DQT_VERSION_STR=\&quot;6.2.1\&quot; -D_LARGEFILE64_SOURCE -D_LARGEFILE_SOURCE -I/tmp/qt-20211111-25903-1lfdcgp/qt-everywhere-src-6.2.1/qtbase/src/corelib/Core_autogen/include
  -I/tmp/qt-20211111-25903-1lfdcgp/qt-everywhere-src-6.2.1/qtbase/include
  -I/tmp/qt-20211111-25903-1lfdcgp/qt-everywhere-src-6.2.1/qtbase/include/QtCore
  -I/tmp/qt-20211111-25903-1lfdcgp/qt-everywhere-src-6.2.1/qtbase/lib/QtCore.framework/Headers
  -I/tmp/qt-20211111-25903-1lfdcgp/qt-everywhere-src-6.2.1/qtbase/src/corelib
  -I/tmp/qt-20211111-25903-1lfdcgp/qt-everywhere-src-6.2.1/qtbase/src/corelib/global
  -I/tmp/qt-20211111-25903-1lfdcgp/qt-everywhere-src-6.2.1/qtbase/src/corelib/kernel
  -I/tmp/qt-20211111-25903-1lfdcgp/qt-everywhere-src-6.2.1/qtbase/src/corelib/../3rdparty/tinycbor/src
  -I/tmp/qt-20211111-25903-1lfdcgp/qt-everywhere-src-6.2.1/qtbase/include/QtCore/6.2.1
  -I/tmp/qt-20211111-25903-1lfdcgp/qt-everywhere-src-6.2.1/qtbase/include/QtCore/6.2.1/QtCore
  -I/tmp/qt-20211111-25903-1lfdcgp/qt-everywhere-src-6.2.1/qtbase/src/corelib/../3rdparty/forkfd -I/tmp/qt-20211111-25903-1lfdcgp/qt-everywhere-src-6.2.1/qtbase/src/corelib/.rcc
  -I/tmp/qt-20211111-25903-1lfdcgp/qt-everywhere-src-6.2.1/qtbase/mkspecs/macx-clang
  -I/usr/local/Cellar/libb2/0.98.1/include -I/usr/local/include/glib-2.0 -I/usr/local/lib/glib-2.0/include -I/tmp/qt-20211111-25903-1lfdcgp/qt-everywhere-src-6.2.1/qtbase/src/xml/Xml_autogen/include
  -I/tmp/qt-20211111-25903-1lfdcgp/qt-everywhere-src-6.2.1/qtbase/include/QtXml
  -I/tmp/qt-20211111-25903-1lfdcgp/qt-everywhere-src-6.2.1/qtbase/lib/QtXml.framework/Headers
  -I/tmp/qt-20211111-25903-1lfdcgp/qt-everywhere-src-6.2.1/qtbase/src/xml
  -I/tmp/qt-20211111-25903-1lfdcgp/qt-everywhere-src-6.2.1/qtbase/include/QtXml/6.2.1
  -I/tmp/qt-20211111-25903-1lfdcgp/qt-everywhere-src-6.2.1/qtbase/include/QtXml/6.2.1/QtXml
  -I/tmp/qt-20211111-25903-1lfdcgp/qt-everywhere-src-6.2.1/qtbase/src/tools/bootstrap/..
  -I/tmp/qt-20211111-25903-1lfdcgp/qt-everywhere-src-6.2.1/qtbase/src/tools/bootstrap/../../3rdparty/tinycbor/src
  -DNDEBUG -O2 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.14.sdk
  -mmacosx-version-min=10.13 -fPIC -fvisibility=hidden -fvisibility-inlines-hidden -Wall -Wextra -ffunction-sections -fdata-sections -std=gnu++17 -MD -MT qtbase/src/tools/bootstrap/CMakeFiles/Bootstrap.dir/__/__/corelib/kernel/qmetatype.cpp.o
  -MF qtbase/src/tools/bootstrap/CMakeFiles/Bootstrap.dir/__/__/corelib/kernel/qmetatype.cpp.o.d
  -o qtbase/src/tools/bootstrap/CMakeFiles/Bootstrap.dir/__/__/corelib/kernel/qmetatype.cpp.o
  -c /tmp/qt-20211111-25903-1lfdcgp/qt-everywhere-src-6.2.1/qtbase/src/corelib/kernel/qmetatype.cpp /tmp/qt-20211111-25903-1lfdcgp/qt-everywhere-src-6.2.1/qtbase/src/corelib/kernel/qmetatype.cpp:1005:9: error: constexpr if condition is not a constant expression
          INTEGRAL_CONVERTER(Bool);
          ^ /tmp/qt-20211111-25903-1lfdcgp/qt-everywhere-src-6.2.1/qtbase/src/corelib/kernel/qmetatype.cpp:957:27: note: expanded from macro 'INTEGRAL_CONVERTER'
          else if constexpr(std::is_signed_v&lt;To&gt;) \
                            ^ /tmp/qt-20211111-25903-1lfdcgp/qt-everywhere-src-6.2.1/qtbase/src/corelib/kernel/qmetatype.cpp:1005:9: error: constexpr if condition is not a constant expression /tmp/qt-20211111-25903-1lfdcgp/qt-everywhere-src-6.2.1/qtbase/src/corelib/kernel/qmetatype.cpp:967:27: note: expanded from macro 'INTEGRAL_CONVERTER'
          else if constexpr(std::is_signed_v&lt;To&gt;) \
                            ^ 2 errors generated.
  </code></pre>
  <p>How can I fix that these errors?</p>