- `no-auto-check-cfg` — disable auto check-cfg (only for `--check-cfg` tests)
- [`revisions`](compiletest.md#revisions) — compile multiple times
- [`unused-revision-names`](compiletest.md#ignoring-unused-revision-names) -
      suppress tidy checks for mentioning unknown revision names
-[`forbid-output`](compiletest.md#incremental-tests) — incremental cfail rejects
      output pattern
- [`should-ice`](compiletest.md#incremental-tests) — incremental cfail should
      ICE
- [`reference`] — an annotation linking to a rule in the reference


### Tool-specific directives

The following directives affect how certain command-line tools are invoked, in
test suites that use those tools:

- `filecheck-flags` adds extra flags when running LLVM's `FileCheck` tool.
  - Used by [codegen tests](compiletest.md#codegen-tests),
  [assembly tests](compiletest.md#assembly-tests), and
  [MIR-opt tests](compiletest.md#mir-opt-tests).
- `llvm-cov-flags` adds extra flags when running LLVM's `llvm-cov` tool.
  - Used by [coverage tests](compiletest.md#coverage-tests) in `coverage-run` mode.


## Substitutions

Directive values support substituting a few variables which will be replaced
with their corresponding value. For example, if you need to pass a compiler flag
with a path to a specific file, something like the following could work:

```rust,ignore
//@ compile-flags: --remap-path-prefix={{src-base}}=/the/src
```

Where the sentinel `{{src-base}}` will be replaced with the appropriate path
described below:

- `{{cwd}}`: The directory where compiletest is run from. This may not be the
  root of the checkout, so you should avoid using it where possible.
  - Examples: `/path/to/rust`, `/path/to/build/root`
- `{{src-base}}`: The directory where the test is defined. This is equivalent to
  `$DIR` for [output normalization].
  - Example: `/path/to/rust/tests/ui/error-codes`
- `{{build-base}}`: The base directory where the test's output goes. This is
  equivalent to `$TEST_BUILD_DIR` for [output normalization].
  - Example: `/path/to/rust/build/x86_64-unknown-linux-gnu/test/ui`
- `{{rust-src-base}}`: The sysroot directory where libstd/libcore/... are
  located
- `{{sysroot-base}}`: Path of the sysroot directory used to build the test.
  - Mainly intended for `ui-fulldeps` tests that run the compiler via API.
- `{{target-linker}}`: Linker that would be passed to `-Clinker` for this test,
  or blank if no linker override is active.
  - Mainly intended for `ui-fulldeps` tests that run the compiler via API.
- `{{target}}`: The target the test is compiling for
  - Example: `x86_64-unknown-linux-gnu`

See
[`tests/ui/commandline-argfile.rs`](https://github.com/rust-lang/rust/blob/master/tests/ui/argfile/commandline-argfile.rs)
for an example of a test that uses this substitution.



## Adding a directive

One would add a new directive if there is a need to define some test property or
behavior on an individual, test-by-test basis. A directive property serves as
the directive's backing store (holds the command's current value) at runtime.

To add a new directive property:

1. Look for the `pub struct TestProps` declaration in
   [`src/tools/compiletest/src/header.rs`] and add the new public property to
   the end of the declaration.
2. Look for the `impl TestProps` implementation block immediately following the
   struct declaration and initialize the new property to its default value.

### Adding a new directive parser

When `compiletest` encounters a test file, it parses the file a line at a time
by calling every parser defined in the `Config` struct's implementation block,
also in [`src/tools/compiletest/src/header.rs`] (note that the `Config` struct's
declaration block is found in [`src/tools/compiletest/src/common.rs`]).
`TestProps`'s `load_from()` method will try passing the current line of text to
each parser, which, in turn typically checks to see if the line begins with a
particular commented (`//@`) directive such as `//@ must-compile-successfully`
or `//@ failure-status`. Whitespace after the comment marker is optional.