Put `intrinsics::unreachable` on a possible path to stabilization
Mark it with the `unreachable` feature and put it into the `mem` module.
This is a pretty straight-forward API that can already be simulated in
stable Rust by using `transmute` to create an uninhabited enum that can
be matched.
AddValidation: handle Call terminators into blocks that have multiple incoming edges
The old code was just wrong: It would add validation on paths that don't even come from the call, and it would add multiple validations if multiple calls end return to the same block.
Encode proper module spans in crate metadata.
The spans previously encoded only span the first token after the opening
brace, up to the closing brace of inline `mod` declarations. Thus, when
examining exports from an external crate, the spans don't include the
header of inline `mod` declarations.
r? @eddyb
Provide more explanation for Deref in String docs
While working on a different project I encountered a point of confusion where using `&String` to dereference a `String` into `&str` did not compile. I found the explanation of [String Deref](https://doc.rust-lang.org/std/string/struct.String.html#deref), thought that it matched what I was trying to do, and was confused as to why my program did not compile when the docs stated that it would work with 'any function which takes a `&str`'. At the bottom it is mentioned that this will 'generally' work, unless `String` is needed, but I found this statement confusing based on the previous claim of 'any'. Looking further into the docs I was able to find the function `as_str()` that works instead.
I thought it might be helpful to mention here deref coercion, an instance in which using `&String` does not work, to explain why it does not work, then direct users to a different option that should work in this instance. A user casually skimming the page will likely come to this explanation first, then find `as_str()` later, but be no the wiser as to what potentially went wrong.
r? @steveklabnik
Reexport all SyntaxExtension variants
This was previously done very inconsistently and made matches look weird since some variants had the `SyntaxExtension::` prefix while others didn't.
Detect relative urls in tidy check
This came up in #43631: there can be long relative urls in Markdown comments, that do not start with `http://` or `https://`, so the tidy check will not detect them as urls and complain about the line length. This PR adds detection of relative urls starting with `../`.
E0122: clarify wording
I *assume* the reason these constraints are not hard errors is backwards compatibility. If yes, I think the error explanation (at least the long form) should be clearer about that, which is what this PR does.
If not, the explanation should give some other suitable explanation.
Some assorted region hashing fixes.
This PR contains three changes.
1. It changes what we implement `HashStable` for. Previously, the trait was implemented for things in the local `TyCtxt`. That was OK, since we only invoked hashing with a `TyCtxt<'_, 'tcx, 'tcx>` where there is no difference. With query result hashing this becomes a problem though. So we now implement `HashStable` for things in `'gcx`.
2. The PR makes the regular `HashStable` implementation *not* anonymize late-bound regions anymore. It's a waste of computing resources and it's not clear that it would always be correct to do so.
3. The PR adds an option for stable hashing to treat all regions as erased and uses this new option when computing the `TypeId`. This should help with https://github.com/rust-lang/rust/issues/41875.
I did not add a test case for (3) since that's not possible yet. But it looks like @zackmdavis has something in the pipeline there `:)`.
r? @eddyb
Make a disable-jemalloc build work
Fixes#43510. I've tested this up to building a stage1 compiler.
r? @alexcrichton
cc @cuviper @vorner
@cuviper your fix was almost correct, you just had a stray `!` in there which caused the second error you saw.
Non-lexical lifetimes region renumberer
Regenerates region variables for all regions in a cloned MIR in the nll mir pass. This is part of the work for #43234.
Hint correct extern constant syntax
Error message for `extern "C" { const …}` is terse, and the right syntax is hard to guess given unfortunate difference between meaning of `static` in C and Rust.
I've added a hint for the right syntax.
rustc: Rearchitect lints to be emitted more eagerly
In preparation for incremental compilation this commit refactors the lint
handling infrastructure in the compiler to be more "eager" and overall more
incremental-friendly. Many passes of the compiler can emit lints at various
points but before this commit all lints were buffered in a table to be emitted
at the very end of compilation. This commit changes these lints to be emitted
immediately during compilation using pre-calculated lint level-related data
structures.
Linting today is split into two phases, one set of "early" lints run on the
`syntax::ast` and a "late" set of lints run on the HIR. This commit moves the
"early" lints to running as late as possible in compilation, just before HIR
lowering. This notably means that we're catching resolve-related lints just
before HIR lowering. The early linting remains a pass very similar to how it was
before, maintaining context of the current lint level as it walks the tree.
Post-HIR, however, linting is structured as a method on the `TyCtxt` which
transitively executes a query to calculate lint levels. Each request to lint on
a `TyCtxt` will query the entire crate's 'lint level data structure' and then go
from there about whether the lint should be emitted or not.
The query depends on the entire HIR crate but should be very quick to calculate
(just a quick walk of the HIR) and the red-green system should notice that the
lint level data structure rarely changes, and should hopefully preserve
incrementality.
Overall this resulted in a pretty big change to the test suite now that lints
are emitted much earlier in compilation (on-demand vs only at the end). This in
turn necessitated the addition of many `#![allow(warnings)]` directives
throughout the compile-fail test suite and a number of updates to the UI test
suite.
Closes https://github.com/rust-lang/rust/issues/42511
Fixed mutable vars being marked used when they weren't
#### NB : bootstrapping is slow on my machine, even with `keep-stage` - fixes for occurances in the current codebase are <s>in the pipeline</s> done. This PR is being put up for review of the fix of the issue.
Fixes#43526, Fixes#30280, Fixes#25049
### Issue
Whenever the compiler detected a mutable deref being used mutably, it marked an associated value as being used mutably as well. In the case of derefencing local variables which were mutable references, this incorrectly marked the reference itself being used mutably, instead of its contents - with the consequence of making the following code emit no warnings
```
fn do_thing<T>(mut arg : &mut T) {
... // don't touch arg - just deref it to access the T
}
```
### Fix
Make dereferences not be counted as a mutable use, but only when they're on borrows on local variables.
#### Why not on things other than local variables?
* Whenever you capture a variable in a closure, it gets turned into a hidden reference - when you use it in the closure, it gets dereferenced. If the closure uses the variable mutably, that is actually a mutable use of the thing being dereffed to, so it has to be counted.
* If you deref a mutable `Box` to access the contents mutably, you are using the `Box` mutably - so it has to be counted.
Avoid calling the column!() macro in panic
Closes#43057
This "fix" adds a new macro called `__rust_unstable_column` and to use it instead of the `column` macro inside panic. The new macro can be shadowed as well as `column` can, but its very likely that there is no code that does this in practice.
There is no real way to make "unstable" macros that are usable by stable macros, so we do the next best thing and prefix the macro with `__rust_unstable` to make sure people recognize it is unstable.
r? @alexcrichton
