crate-attr

The tracking issue for this feature is: #138287.

The -Z crate-attr flag allows you to inject attributes into the crate root. For example, -Z crate-attr=crate_name="test" acts as if #![crate_name="test"] were present before the first source line of the crate root.

To inject multiple attributes, pass -Z crate-attr multiple times.

Formally, the expansion behaves as follows:

1. The crate is parsed as if -Z crate-attr were not present.
2. The attributes in -Z crate-attr are parsed.
3. The attributes are injected at the top of the crate root.
4. Macro expansion is performed.