gn analyze output:
{
  "compile_targets": [],
  "status": "No dependency",
  "test_targets": []
}
gn analyze input:
{
  "files": [
    "//libcxx/docs/Status/Cxx2cIssues.csv",
    "//libcxx/include/streambuf",
    "//libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.cons/copy.pass.cpp",
    "//libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.protected/streambuf.assign/assign.pass.cpp",
    "//libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.protected/streambuf.assign/swap.pass.cpp",
    "//libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.protected/streambuf.get.area/setg.assert.pass.cpp",
    "//libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.protected/streambuf.put.area/setp.assert.pass.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": []
}