QtDeclarative build fails on macOS

In file included from /Users/lpotter/depot/qt/qt5/qtdeclarative/src/qml/parser/qqmljslexer.cpp:42:
/Users/lpotter/depot/qt/qt5/qtdeclarative/src/qml/parser/qqmljskeywords_p.h:752:33: error: no member named 'T_REQUIRED' in 'QQmlJS::Lexer'; did you mean 'T_RETURN'?

return Lexer::T_REQUIRED;
~~~~~~_^~~~~~~~~
T_RETURN
/Users/lpotter/development/builds/qt5-base/include/QtQml/5.15.0/QtQml/../../../../../../qtdeclarative/src/qml/qqmljsgrammar_p.h:149:9: note: 'T_RETURN' declared here
T_RETURN = 60,
^
/Users/lpotter/depot/qt/qt5/qtdeclarative/src/qml/parser/qqmljslexer.cpp:848:28: error: use of undeclared identifier 'T_FUNCTION_STAR'; did you mean 'T_FUNCTION'?
kind = T_FUNCTION_STAR;
^~~~~~~~~~~~~~~
T_FUNCTION
/Users/lpotter/development/builds/qt5-base/include/QtQml/5.15.0/QtQml/../../../../../../qtdeclarative/src/qml/qqmljsgrammar_p.h:99:9: note: 'T_FUNCTION' declared here
T_FUNCTION = 22,
^
/Users/lpotter/depot/qt/qt5/qtdeclarative/src/qml/parser/qqmljslexer.cpp:1435:20: error: no member named 'T_FUNCTION_STAR' in 'QQmlJSGrammar'; did you mean 'T_FUNCTION'?
QQmlJSGrammar::T_FUNCTION_STAR,
~~~~~~~~~~~~~~_^~~~~~~~~~~~~~
T_FUNCTION
/Users/lpotter/development/builds/qt5-base/include/QtQml/5.15.0/QtQml/../../../../../../qtdeclarative/src/qml/qqmljsgrammar_p.h:99:9: note: 'T_FUNCTION' declared here
T_FUNCTION = 22,
^
3 errors generated.
shared:ERROR: compiler frontend failed to generate LLVM bitcode, halting
make[2]: *** [.obj/qqmljslexer.o] Error 1
make[2]: *** Waiting for unfinished jobs....
make[1]: *** [sub-qml-make_first-ordered] Error 2
make: *** [sub-src-make_first] Error 2