print=check-cfg
The tracking issue for this feature is: #125704.
This option of the --print flag print the list of all the expected cfgs.
This is related to the --check-cfg flag which allows specifying arbitrary expected
names and values.
This print option outputs compatible --check-cfg arguments with a reduced syntax where all the
expected values are on the same line and values(...) is always explicit.
--check-cfg | --print=check-cfg |
|---|---|
cfg(foo) | `cfg(foo, values(none())) |
cfg(foo, values("bar")) | cfg(foo, values("bar")) |
cfg(foo, values(none(), "bar")) | cfg(foo, values(none(), "bar")) |
cfg(foo, values(any()) | cfg(foo, values(any()) |
cfg(foo, values()) | cfg(foo, values()) |
cfg(any()) | cfg(any()) |
| nothing | nothing |
The print option includes well known cfgs.
To be used like this:
rustc --print=check-cfg -Zunstable-options lib.rs
Note: Users should be resilient when parsing, in particular against new predicates that may be added in the future.