Unavailability to compile Clang Refactoring Engine for LLVM/Clang 10

It is impossible to compile Qt Creator using Clang 10.0.0git built from source due to several errors produced by files included in Clang refactoring engine. There are many function overrides are now considered wrong and some type mismatches.

Now I found no workaround for this issue excepting turning off the whole building of Clang refactoring engine removing the following lines

QTC_DISABLE_CLANG_REFACTORING=$$(QTC_DISABLE_CLANG_REFACTORING)
isEmpty(QTC_DISABLE_CLANG_REFACTORING) {
 SUBDIRS += clangrefactoringbackend
 SUBDIRS += clangpchmanagerbackend
}

from src/tools/tools.pro and following

QTC_DISABLE_CLANG_REFACTORING=$$(QTC_DISABLE_CLANG_REFACTORING)
isEmpty(QTC_DISABLE_CLANG_REFACTORING) {
 SUBDIRS += clangrefactoring
 SUBDIRS += clangpchmanager
}

from src/plugins/plugins.pro. The attempts to set QTC_DISABLE_CLANG_REFACTORING variable to avoid the build brought no result.