Macro rustc_const_eval::interpret::validity::try_validation
source · macro_rules! try_validation { ($e:expr, $where:expr, $( $( $p:pat_param )|+ => $kind: expr ),+ $(,)? ) => { ... }; }
Expand description
If $e throws an error matching the pattern, throw a validation failure.
Other errors are passed back to the caller, unchanged – and if they reach the root of
the visitor, we make sure only validation errors and InvalidProgram
errors are left.
This lets you use the patterns as a kind of validation list, asserting which errors
can possibly happen:
let v = try_validation!(some_fn(), some_path, {
Foo | Bar | Baz => { "some failure" },
});
The patterns must be of type UndefinedBehaviorInfo
.
An additional expected parameter can also be added to the failure message:
let v = try_validation!(some_fn(), some_path, {
Foo | Bar | Baz => { "some failure" } expected { "something that wasn't a failure" },
});
An additional nicety is that both parameters actually take format args, so you can just write the format string in directly:
let v = try_validation!(some_fn(), some_path, {
Foo | Bar | Baz => { "{:?}", some_failure } expected { "{}", expected_value },
});