Hmm ... It's impossible ;-) This RPM doesn't exist on any FTP server

Provides :
clang-devel
clang-devel(x86-64)
cmake(Clang)

Requires :

clang(x86-64) = 8.0.0-20181104svn346097.fc27
clang-tools-extra(x86-64) = 8.0.0-20181104svn346097.fc27
cmake-filesystem(x86-64)
rpmlib(CompressedFileNames) <= 3.0.4-1
rpmlib(FileDigests) <= 4.6.0-1
rpmlib(PayloadFilesHavePrefix) <= 4.0-1
rpmlib(PayloadIsXz) <= 5.2-1

Content of RPM :
/usr/include/clang
/usr/include/clang-c
/usr/include/clang-c/BuildSystem.h
/usr/include/clang-c/CXCompilationDatabase.h
/usr/include/clang-c/CXErrorCode.h
/usr/include/clang-c/CXString.h
/usr/include/clang-c/Documentation.h
/usr/include/clang-c/Index.h
/usr/include/clang-c/Platform.h
/usr/include/clang/ARCMigrate
/usr/include/clang/ARCMigrate/ARCMT.h
/usr/include/clang/ARCMigrate/ARCMTActions.h
/usr/include/clang/ARCMigrate/FileRemapper.h
/usr/include/clang/AST
/usr/include/clang/AST/APValue.h
/usr/include/clang/AST/AST.h
/usr/include/clang/AST/ASTConsumer.h
/usr/include/clang/AST/ASTContext.h
/usr/include/clang/AST/ASTDiagnostic.h
/usr/include/clang/AST/ASTFwd.h
/usr/include/clang/AST/ASTImporter.h
/usr/include/clang/AST/ASTLambda.h
/usr/include/clang/AST/ASTMutationListener.h
/usr/include/clang/AST/ASTStructuralEquivalence.h
/usr/include/clang/AST/ASTTypeTraits.h
/usr/include/clang/AST/ASTUnresolvedSet.h
/usr/include/clang/AST/ASTVector.h
/usr/include/clang/AST/Attr.h
/usr/include/clang/AST/AttrDump.inc
/usr/include/clang/AST/AttrImpl.inc
There is 560 files more in these RPM.