a fn pointer doesn't implement `Fn`/`FnMut`/`FnOnce` if its return type isn't sized
I stumbled upon #83915 which hasn't received much attention recently, and I wanted to revive it since this is one existing soundness hole that seems pretty easy to fix.
I'm not actually sure that the [alternative approach described here](https://github.com/rust-lang/rust/pull/83915#issuecomment-823643322) is sufficient, given the `src/test/ui/function-pointer/unsized-ret.rs` example I provided below. Rebasing the branch mentioned in that comment and testing that UI test, it seems that we actually end up only observing that `str: !Sized` during monomorphization, whereupon we ICE. Even if we were to fix that ICE, ideally we'd be raising an error that a fn pointer is being used badly during _typecheck_ instead of monomorphization, hence adapting the original approach in #83915.
I am happy to close this if people would prefer we rebase the original PR and land that -- I am partly opening to be annoying and get people thinking about this unsoundness again ❤️😸
cc: `@estebank` and `@nikomatsakis`
r? types
Here's a link to the thread: https://rust-lang.zulipchat.com/#narrow/stream/144729-t-types/topic/PR.20.2383915/near/235421351 for more context.
Improve error for when query is unsupported by crate
This is an improvement to the error message mentioned on #101666. It seems like a good idea to also add [this link to the rustc-dev-guide](https://rustc-dev-guide.rust-lang.org/query.html), if explaining the query system in detail is a concern here, but I'm unsure if there is any restrictions on adding links to error messages.
Rollup of 11 pull requests
Successful merges:
- #101389 (Tone down explanation on RefCell::get_mut)
- #101798 (Make `from_waker`, `waker` and `from_raw` unstably `const`)
- #101881 (Remove an unused struct field `late_bound`)
- #101904 (Add help for invalid inline argument)
- #101966 (Add unit test for identifier Unicode emoji diagnostics)
- #101979 (Update release notes for 1.64)
- #101985 (interpret: expose generate_stacktrace without full InterpCx)
- #102004 (Try to clarify what's new in 1.64.0 ffi types)
- #102005 (rustdoc: remove unused CSS `td.summary-column`)
- #102017 (Add all submodules to the list of directories tidy skips)
- #102019 (Remove backed off PRs from relnotes)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
Avoid duplicating StorageLive in let-else
cc `@est31`
Fix#101867Fix#101932#101410 introduced directives to activate storages of bindings in let-else earlier. However, since it is using the machinery of `match` and friends for pattern matching and binding, those storages are activated for the second time. This PR adjusts this behavior and avoid the duplicated activation for let-else statements.
interpret: expose generate_stacktrace without full InterpCx
In Miri we sometimes want to emit diagnostics without having a full `&InterpCx` available. To avoid duplicating code, this adds a way to get a stacktrace from an arbitrary slice of interpreter frames, that Miri can use with access to just a thread manager.
Add help for invalid inline argument
Fixes#101712
Removed 1 part of the test as its identical with another one. Do let me know if this is undesirable, so I can revert those changes.
`EarlyBinder` prevent misuse
folding a type before substituting is pretty much always wrong and could happen by accident, e.g. see https://github.com/rust-lang/rust/pull/99798#discussion_r968666538
this PR removes the `TypeFoldable` and `TypeVisitable` impl from `EarlyBinder`.
r? types cc `@jackh726`
change AccessLevels representation
Part of RFC (https://github.com/rust-lang/rust/issues/48054). This patch implements effective visibility table with basic methods and change AccessLevels table representation according to it.
r? ``@petrochenkov``
add note for `layout_of` when query depth overflows
Fixes#101747
Added `try_find_layout_root` function to add a note for `layout_of` when query depth overflows. This would make the error in #101747 look like this:
```
error: queries overflow the depth limit!
|
note: Query depth increased by 66 when computing layout of `core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<core::option::Option<alloc::boxed::Box<alloc::string::String>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>`!
--> D:\rust-backup\parallel_rust\query_depth.rs:40:1
|
40 | fn main() {
| ^^^^^^^^^
error: aborting due to previous error
```
cc ``@semicoleon``
