gn analyze output:
{
  "compile_targets": [],
  "status": "No dependency",
  "test_targets": []
}
gn analyze input:
{
  "files": [
    "//libcxx/include/fstream",
    "//libcxx/include/sstream",
    "//libcxx/include/strstream",
    "//libcxx/include/syncstream",
    "//libcxx/test/libcxx/depr/depr.strstream/nodiscard.verify.cpp",
    "//libcxx/test/libcxx/input.output/file.streams/fstreams/nodiscard.verify.cpp",
    "//libcxx/test/libcxx/input.output/string.streams/nodiscard.verify.cpp",
    "//libcxx/test/libcxx/input.output/synchstream/nodiscard.verify.cpp"
  ],
  "test_targets": [
    "//clang-tools-extra/clangd/test:check-clangd",
    "//clang-tools-extra/test:check-clang-tools",
    "//clang/test:check-clang",
    "//compiler-rt/test/hwasan:check-hwasan",
    "//lld/test:check-lld",
    "//llvm/test:check-llvm"
  ],
  "additional_compile_targets": []
}