ninja: Entering directory `out/gn'
[1/1] Regenerating ninja files
FAILED: build.ninja 
../../llvm/utils/gn/bin/linux-amd64/gn --root=../.. -q --dotfile=../../llvm/utils/gn/.gn gen .
ERROR Unresolved dependencies.
//clang/lib/Basic:Basic(//llvm/utils/gn/build/toolchain:unix)
  needs //clang/include/clang/Basic:AttrParsedAttrList(//llvm/utils/gn/build/toolchain:unix)
//clang/lib/Sema:Sema(//llvm/utils/gn/build/toolchain:unix)
  needs //clang/include/clang/Basic:AttrParsedAttrList(//llvm/utils/gn/build/toolchain:unix)

ninja: error: rebuilding 'build.ninja': subcommand failed
Command '['ninja', '-C', 'out/gn']' returned non-zero exit status 1.