diff --git a/src/known-directives.rs b/src/known-directives.rs
new file mode 100644
index 0000000..fb94261
--- /dev/null
+++ b/src/known-directives.rs
@@ -0,0 +1,236 @@
+// Copied from https://github.com/rust-lang/rust/blob/master/src/tools/compiletest/src/command-list.rs
+pub const KNOWN_DIRECTIVE_NAMES: &[&str] = &[
+    // tidy-alphabetical-start
+    "assembly-output",
+    "aux-bin",
+    "aux-build",
+    "aux-codegen-backend",
+    "aux-crate",
+    "build-aux-docs",
+    "build-fail",
+    "build-pass",
+    "check-fail",
+    "check-pass",
+    "check-run-results",
+    "check-stdout",
+    "check-test-line-numbers-match",
+    "compare-output-lines-by-subset",
+    "compile-flags",
+    "doc-flags",
+    "dont-check-compiler-stderr",
+    "dont-check-compiler-stdout",
+    "dont-check-failure-status",
+    "edition",
+    "error-pattern",
+    "exec-env",
+    "failure-status",
+    "filecheck-flags",
+    "forbid-output",
+    "force-host",
+    "ignore-16bit",
+    "ignore-32bit",
+    "ignore-64bit",
+    "ignore-aarch64",
+    "ignore-aarch64-unknown-linux-gnu",
+    "ignore-android",
+    "ignore-apple",
+    "ignore-arm",
+    "ignore-avr",
+    "ignore-beta",
+    "ignore-cdb",
+    "ignore-compare-mode-next-solver",
+    "ignore-compare-mode-polonius",
+    "ignore-cross-compile",
+    "ignore-debug",
+    "ignore-eabi",
+    "ignore-emscripten",
+    "ignore-endian-big",
+    "ignore-freebsd",
+    "ignore-fuchsia",
+    "ignore-gdb",
+    "ignore-gdb-version",
+    "ignore-gnu",
+    "ignore-haiku",
+    "ignore-horizon",
+    "ignore-i686-pc-windows-gnu",
+    "ignore-i686-pc-windows-msvc",
+    "ignore-illumos",
+    "ignore-ios",
+    "ignore-linux",
+    "ignore-lldb",
+    "ignore-llvm-version",
+    "ignore-loongarch64",
+    "ignore-macabi",
+    "ignore-macos",
+    "ignore-mode-assembly",
+    "ignore-mode-codegen",
+    "ignore-mode-codegen-units",
+    "ignore-mode-coverage-map",
+    "ignore-mode-coverage-run",
+    "ignore-mode-crashes",
+    "ignore-mode-debuginfo",
+    "ignore-mode-incremental",
+    "ignore-mode-js-doc-test",
+    "ignore-mode-mir-opt",
+    "ignore-mode-pretty",
+    "ignore-mode-run-make",
+    "ignore-mode-run-pass-valgrind",
+    "ignore-mode-rustdoc",
+    "ignore-mode-rustdoc-json",
+    "ignore-mode-ui",
+    "ignore-mode-ui-fulldeps",
+    "ignore-msp430",
+    "ignore-msvc",
+    "ignore-musl",
+    "ignore-netbsd",
+    "ignore-nightly",
+    "ignore-none",
+    "ignore-nto",
+    "ignore-nvptx64",
+    "ignore-nvptx64-nvidia-cuda",
+    "ignore-openbsd",
+    "ignore-pass",
+    "ignore-remote",
+    "ignore-riscv64",
+    "ignore-s390x",
+    "ignore-sgx",
+    "ignore-spirv",
+    "ignore-stable",
+    "ignore-stage1",
+    "ignore-stage2",
+    "ignore-test",
+    "ignore-thumb",
+    "ignore-thumbv8m.base-none-eabi",
+    "ignore-thumbv8m.main-none-eabi",
+    "ignore-tvos",
+    "ignore-unix",
+    "ignore-unknown",
+    "ignore-uwp",
+    "ignore-visionos",
+    "ignore-vxworks",
+    "ignore-wasi",
+    "ignore-wasm",
+    "ignore-wasm32",
+    "ignore-wasm32-bare",
+    "ignore-wasm64",
+    "ignore-watchos",
+    "ignore-windows",
+    "ignore-windows-gnu",
+    "ignore-windows-msvc",
+    "ignore-x32",
+    "ignore-x86",
+    "ignore-x86_64",
+    "ignore-x86_64-apple-darwin",
+    "ignore-x86_64-unknown-linux-gnu",
+    "incremental",
+    "known-bug",
+    "llvm-cov-flags",
+    "min-cdb-version",
+    "min-gdb-version",
+    "min-lldb-version",
+    "min-llvm-version",
+    "min-system-llvm-version",
+    "needs-asm-support",
+    "needs-dlltool",
+    "needs-dynamic-linking",
+    "needs-force-clang-based-tests",
+    "needs-git-hash",
+    "needs-llvm-components",
+    "needs-profiler-support",
+    "needs-relocation-model-pic",
+    "needs-run-enabled",
+    "needs-rust-lld",
+    "needs-rust-lldb",
+    "needs-sanitizer-address",
+    "needs-sanitizer-cfi",
+    "needs-sanitizer-dataflow",
+    "needs-sanitizer-hwaddress",
+    "needs-sanitizer-kcfi",
+    "needs-sanitizer-leak",
+    "needs-sanitizer-memory",
+    "needs-sanitizer-memtag",
+    "needs-sanitizer-safestack",
+    "needs-sanitizer-shadow-call-stack",
+    "needs-sanitizer-support",
+    "needs-sanitizer-thread",
+    "needs-symlink",
+    "needs-threads",
+    "needs-unwind",
+    "needs-wasmtime",
+    "needs-xray",
+    "no-auto-check-cfg",
+    "no-prefer-dynamic",
+    "normalize-stderr-32bit",
+    "normalize-stderr-64bit",
+    "normalize-stderr-test",
+    "normalize-stdout-test",
+    "only-16bit",
+    "only-32bit",
+    "only-64bit",
+    "only-aarch64",
+    "only-aarch64-unknown-linux-gnu",
+    "only-apple",
+    "only-arm",
+    "only-avr",
+    "only-beta",
+    "only-bpf",
+    "only-cdb",
+    "only-gnu",
+    "only-i686-pc-windows-gnu",
+    "only-i686-pc-windows-msvc",
+    "only-ios",
+    "only-linux",
+    "only-loongarch64",
+    "only-loongarch64-unknown-linux-gnu",
+    "only-macos",
+    "only-mips",
+    "only-mips64",
+    "only-msp430",
+    "only-msvc",
+    "only-nightly",
+    "only-nvptx64",
+    "only-riscv64",
+    "only-sparc",
+    "only-sparc64",
+    "only-stable",
+    "only-thumb",
+    "only-tvos",
+    "only-unix",
+    "only-visionos",
+    "only-wasm32",
+    "only-wasm32-bare",
+    "only-wasm32-wasip1",
+    "only-watchos",
+    "only-windows",
+    "only-windows-gnu",
+    "only-windows-msvc",
+    "only-x86",
+    "only-x86_64",
+    "only-x86_64-fortanix-unknown-sgx",
+    "only-x86_64-pc-windows-gnu",
+    "only-x86_64-pc-windows-msvc",
+    "only-x86_64-unknown-linux-gnu",
+    "pp-exact",
+    "pretty-compare-only",
+    "pretty-expanded",
+    "pretty-mode",
+    "regex-error-pattern",
+    "remap-src-base",
+    "revisions",
+    "run-fail",
+    "run-flags",
+    "run-pass",
+    "run-rustfix",
+    "rustc-env",
+    "rustfix-only-machine-applicable",
+    "should-fail",
+    "should-ice",
+    "stderr-per-bitwidth",
+    "test-mir-pass",
+    "unique-doc-out-dir",
+    "unset-exec-env",
+    "unset-rustc-env",
+    // Used by the tidy check `unknown_revision`.
+    "unused-revision-names",
+    // tidy-alphabetical-end
+];