This is an alternative to https://github.com/rust-lang/rust/pull/29954 for fixing #29857 that seems to me to be more inline with the general strategy around `TyError`. It also includes the fix for #30589 -- in fact, just the minimal change of making `ty_is_local` tolerate `TyError` avoids the ICE, but you get a lot of duplicate error reports, so in the case where the impl's trait reference already includes `TyError`, we just ignore the impl altogether.
cc @arielb1 @sanxiyn
Fixes#29857.
Fixes#30589.
Downgrade unit struct match via S(..) warnings to errors
The error signalling was introduced in #29383
It was noted as a warning-cycle-less regression in #30379Fix#30379
Fixes#18037 "TypedArena cannot handle zero-sized types".
Closes#17931 "improve chunk allocation scheme used by Arena / TypedArena".
Closes#22847 "TypedArena should implement Send". - N.B. Arena cannot implement Send, since it may contain non-Send values.
Closes#18471 "`Arena::alloc_copy_inner` (at least) should be renamed and made public." - Added `Arena::alloc_bytes`.
Closes#18261 "support clearing TypedArena with the chunks preserved". - Only the largest chunk is preserved.
Fix a bug allowing an item and an external crate to collide so long as the external crate is declared after the item. For example,
```rust
mod core { pub fn f() {} } // This would be an error if it followed the `extern crate`
extern crate core; // This declaration is shadowed by the preceding module
fn main() { core::f(); }
```
This is a [breaking-change], but it looks unlikely to cause breakage in practice, and any breakage can be fixed by removing colliding `extern crate` declarations, which are shadowed and hence unused.
This just removes the `Some()` that appeared around terminators in MIR text output after https://github.com/rust-lang/rust/pull/30481 (cc @nagisa). The graphviz is already fixed.
r? @eddyb
the problem is that now "type_is_known_to_be_sized" now returns
false when called on a type with ty_err inside - this prevents
spurious errors (we may want to move the check to check::cast
anyway - see #12894).
len needs to be prefixed by self for this to work. That is something which trips me up all the time. It's reassuring to see that happening to seasoned Rust programmers.
I'm working my way through TRPL beginning at "Syntax and Semantics" as was recommended in a previous version.
I'm expecting the chapter to incrementally build up my knowledge of the language section by section, assuming no prior Rust experience. So it was a bit of a speed-bump to encounter references and the vector type in a code example long before they had been defined and explained.
Another commit in this PR tries to make consistent what is a "chapter" of TRPL versus a "section." Just a nit-pick, but not thinking about that stuff keeps my focus on the important material.
My background: Python programmer since ~2000, with moderate exposure to C, C++, assembly, operating systems, and system architecture in university several years ago.
For your kind consideration, feel welcome to use or drop or rework any part of this.
Fixes#30674
The test seems to work fine and assertion passes. The test seems to also be generated from MIR (LLVM IR has footprint of MIR translator), thus I’m reenabling it.
After a call to `visit_def_id()` missing in `mir::visit::Visitor` but not `mir::visit::MutVisitor` has caused me a couple hours of error hunting, I decided I'd take the time to get rid of the code duplication between the two implementations.
cc @rust-lang/compiler
`TypeFoldable`s can currently be visited inefficiently with an identity folder that is run only for its side effects. This creates a more efficient visitor for `TypeFoldable`s and uses it to implement `RegionEscape` and `HasProjectionTypes`, fixing cleanup issue #20298.
This is a pure refactoring.
It was recently realized that we accept defaulted type parameters everywhere, without feature gate, even though the only place that we really *intended* to accept them were on types. This PR adds a lint warning unless the "type-parameter-defaults" feature is enabled. This should eventually become a hard error.
This is a [breaking-change] in that new feature gates are required (or simply removing the defaults, which is probably a better choice as they have little effect at this time). Results of a [crater run][crater] suggest that approximately 5-15 crates are affected. I didn't do the measurement quite right so that run cannot distinguish "true" regressions from "non-root" regressions, but even the upper bound of 15 affected crates seems relatively minimal.
[crater]: https://gist.github.com/nikomatsakis/760c6a67698bd24253bf
cc @rust-lang/lang
r? @pnkfelix
In a straight-through read of "Syntax and Semantics," the concept of a
"reference" is used here before it is explained. Mention that and link to
the section explaining references.
