Rename and fix nolink-with-link-args test
There are three problems with the nolink-with-link-args test:
* The test fails when using MSVC. It's caused by the `linker-flavor=ld` flag which was added in #46291.
* In its comment, this test tests that "link_args are indeed passed when nolink is specified", but the `nolink` attribute has been removed [a long time ago](https://github.com/rust-lang/rust/pull/12826).
* Pattern has a small typo.
At first I was going to completely remove this test, but there is [a closed pull request for that](https://github.com/rust-lang/rust/pull/21090).
So:
* rename the file as suggested in the closed PR
* adjust the comment
* fix typo in the pattern
* add `ignore-msvc`.
r? @alexcrichton
Fix#56806 by using `delay_span_bug` in object safety layout sanity checks
It's possible that `is_object_safe` is called on a trait method that with an invalid receiver type. This caused an ICE in #56806, because `receiver_is_dispatchable` returns `true` for `self: Box<dyn Trait>`, which causes one of the layout sanity checks in object_safety.rs to fail. Replacing `bug!` with `delay_span_bug` solves this.
The fact that `receiver_is_dispatchable` returns `true` here could be considered a bug. It passes the check that the method implements, though: `Box<dyn Trait>` implements `DispatchFromDyn<Box<dyn Trait>>` because `dyn Trait` implements `Unsize<dyn Trait>`. It would be good to hear what @eddyb and @nikomatsakis think.
Note that I only added a test for the case encountered in #56806. I could not come up with a case that triggered an ICE from the other check, `bug!("receiver when Self = dyn Trait should be ScalarPair, found Scalar")`. There is no way, to my knowledge, that you can make `receiver_is_dispatchable` return true but still have a `Scalar` ABI when `Self = dyn Trait`.
One other case I encountered while debugging #56806 was that if you have a type parameter `T` that implements `Deref<Target=Self>` and `DispatchFromDyn<T>`, and use it as a method receiver, it will cause an ICE during `is_object_safe` because `T` has no layout ([playground](https://play.rust-lang.org/?version=nightly&mode=debug&edition=2018&gist=d9b7497b3be0ca8382fa7d9497263214)):
```rust
trait Trait<T: Deref<Target=Self> + DispatchFromDyn<T>> {
fn foo(self: T) -> dyn Trait<T>;
}
```
I don't intend to remove the ICE there because it is a pathological case, especially since there is no way to implement `DispatchFromDyn<T>` for `T` — the checks in typeck/coherence/builtin.rs do not allow that.
fixes#56806
r? @varkor
panic when calling MaybeUninhabited::into_inner on uninhabited type
I do this by adding an internal-only intrinsic `panic_if_uninhabited`. I have no idea what I am doing here, just mindlessly copying code around, so please review carefully!
NLL: Add closure cannot be moved note.
Fixes#57098.
This PR extends existing logic for checking whether a closure that
is `FnOnce` and therefore moves variables that it captures from the
environment has already been invoked when being invoked again.
Now, this logic will also check whether the closure is being moved after
previously being moved or invoked and add an appropriate note.
r? @pnkfelix
Add support for trait-objects without a principal
The hard-error version of #56481 - should be merged after we do something about the `traitobject` crate.
Fixes#33140.
Fixes#57057.
r? @nikomatsakis
Implement the Re-rebalance coherence RFC
This is the first time I touch anything in the compiler so just tell me if I got something wrong.
Big thanks to @sgrif for the pointers where to look for those things.
cc #55437
It's possible that `is_object_safe` is called on a trait that is ill-formed, and we shouldn't ICE unless there are no errors being raised. Using `delay_span_bug` solves this.
fixes#56806
This commit improves the logic for place descriptions in conflicting
borrow errors so that borrows of union fields have better messages even
when the unions are embedded in other unions or structs.
make `panictry!` private to libsyntax
This commit completely removes usage of the `panictry!` macro from
outside libsyntax. The macro causes parse errors to be fatal, so using
it in libsyntax_ext caused parse failures *within* a syntax extension to
be fatal, which is probably not intended.
Furthermore, this commit adds spans to diagnostics emitted by empty
extensions if they were missing, à la #56491.
Trying to write a `const_fn` lint for Clippy. @oli-obk suggested
[here][link] to use the `is_min_const_fn` function from the
`qualify_min_const_fn` module. However, the module is currently private
and this commit makes it public.
I lack any historical knowledge of the development of the `const_fn`
feature, so I'm not sure if it was private on purpose or not. fwiw, all
modules are already public except `qualify_min_const_fn`.
[link]: https://github.com/rust-lang/rust-clippy/issues/2440#issuecomment-446109978
This ensures that arguments passed via `-C link-arg` can override the
first ones on the command line, for example allowing configuring of the
stack size.
Forbid recursive impl trait
There is no type T, such that `T = [T; 2]`, but impl Trait could sometimes
be to circumvented this.
This patch makes it a hard error for an opaque type to resolve to such a
"type". Before this can be merged it needs
- [x] A better error message - it's good enough for now.
- [x] A crater run (?) to see if this any real-world code
closes#47659
Allow to dispatch fn traits depending on number of parameters
Hello,
By following @eddyb's advise on issue #45510, I managed to have the snippets of code in #45510 and #18952 passing without breaking older diagnostics.
EDIT: the codegen tests breakage I experienced is due to the poor quality of my laptop.
If any kind reviewer has any advice, you are very welcome.
Currently, SelectionContext tries to prevent stack overflow by keeping
track of the current recursion depth. However, this depth tracking is
only used when performing normal section (which includes confirmation).
No such tracking is performed for evaluate_obligation_recursively, which
can allow a stack overflow to occur.
To fix this, this commit tracks the current predicate evaluation depth.
This is done separately from the existing obligation depth tracking:
an obligation overflow can occur across multiple calls to 'select' (e.g.
when fulfilling a trait), while a predicate evaluation overflow can only
happen as a result of a deep recursive call stack.
Fixes#56701
