Previously if --extern was specified it would not override crates in the
standard distribution, leading to issues like #21771. This commit alters the
behavior such that if --extern is passed then it will always override any other
choice of crates and no previous match will be used (unless it is the same path
as --extern).
Closes#21771
Coercions will now attempt to autoderef as needed before reborrowing.
This includes overloaded `Deref`, e.g. `&Rc<T>` coerces to `&T`, and
`DerefMut`, e.g. `&mut Vec<T>` coerces to `&mut [T]` (in addition to `&[T]`).
Closes#21432.
trans: When coercing to `Box<Trait>` or `Box<[T]>`, leave datum in it's original L-/R-value state.
This fixes a subtle issue where temporaries were being allocated (but not necessarily initialized) to the (parent) terminating scope of a match expression; in particular, the code to zero out the temporary emitted by `datum.store_to` is only attached to the particular match-arm for that temporary, but when going down other arms of the match expression, the temporary may falsely appear to have been initialized, depending on what the stack held at that location, and thus may have its destructor erroneously run at the end of the terminating scope.
FIx#20055.
(There may be a latent bug still remaining in `fn into_fat_ptr`, but I am so annoyed by the test/run-pass/coerce_match.rs failures that I want to land this now.)
It was considered to be impossible but actually it can
happen for nested closures. Also, because there must
be nested closures when this happens, we can use more
targeted help message.
Closes#21390Closes#21600
Note: Do not merge until we get a newer snapshot that includes #21374
There was some type inference fallout (see 4th commit) because type inference with `a..b` is not as good as with `range(a, b)` (see #21672).
r? @alexcrichton
explicit form `Fn<A,B>` and now should use `Fn(A) -> B` or
`Fn<A,Output=B>`, but in some cases we get duplicate error
reports. This is mildly annoying and arises because of the main error
and another error from the projection. Might be worth squashing those,
but seems like a separate problem.
