make `ConstEvaluatable` more strict
relevant zulip discussion: https://rust-lang.zulipchat.com/#narrow/stream/146212-t-compiler.2Fconst-eval/topic/.60ConstEvaluatable.60.20generic.20functions/near/204125452
Let's see how much this impacts. Depending on how this goes this should probably be a future compat warning.
Short explanation: we currently forbid anonymous constants which depend on generic types, e.g. `[0; std::mem::size_of::<T>]` currently errors.
We previously checked this by evaluating the constant and returned an error if that failed. This however allows things like
```rust
const fn foo<T>() -> usize {
if std::mem::size_of::<*mut T>() < 8 { // size of *mut T does not depend on T
std::mem::size_of::<T>()
} else {
8
}
}
fn test<T>() {
let _ = [0; foo::<T>()];
}
```
which is a backwards compatibility hazard. This also has worrying interactions with mir optimizations (https://github.com/rust-lang/rust/pull/74491#issuecomment-661890421) and intrinsics (#74538).
r? `@oli-obk` `@eddyb`
BTreeMap mutable iterators should not take any reference to visited nodes during iteration
Fixes#73915, overlapping mutable references during BTreeMap iteration
r? `@RalfJung`
Make rustdoc output deterministic for UI tests
Closes https://github.com/rust-lang/rust/issues/76442 (hopefully, since it's non-deterministic I don't have a way to test).
r? `@Mark-Simulacrum`
cc `@GuillaumeGomez`
rustdoc: Fix font CSS for crate lists
I had put it in the wrong file in #76126. This should fix it now. Thank
you to `@ollie27` for pointing this out!
---
`@rustbot` modify labels: T-rustdoc C-bug
Update cargo
8 commits in 126907a7cfccbe93778530e6a6bbaa3adb6c515c..875e0123259b0b6299903fe4aea0a12ecde9324f
2020-08-31 20:42:11 +0000 to 2020-09-08 20:17:21 +0000
- Lowercase and remove periods in error messages for consistency (rust-lang/cargo#8655)
- Allow running build-man.sh from any directory (rust-lang/cargo#8682)
- docs: add details for cargo check pass where cargo build fail (rust-lang/cargo#8677)
- Fix nightly exported_priv_warning test. (rust-lang/cargo#8678)
- fix mdbook test with ```ignore/text/sh/console (rust-lang/cargo#8674)
- End CACHEDIR.TAG with newline (rust-lang/cargo#8672)
- Fixed the fossil repo initialization actually run commands (rust-lang/cargo#8671)
- Remove asciidoc attribute in cargo-metadata man page. (rust-lang/cargo#8670)
Add help note to unconstrained const parameter
Resolves#68366, since it is currently intended behaviour.
If demonstrating `T -> U` is injective, there should be an additional word that it is not **yet** supported.
r? @lcnr
Fix HashMap visualizers in Visual Studio (Code)
CDB (as used in unit tests) doesn't care that we're using static_cast between unrelated types (`u8*` to `tuple<$T1, $T2>*`).
Visual Studio & Visual Studio Code care. These should've been reinterpret_cast or C casts.
Credit to @petrochenkov per https://github.com/rust-lang/rust/issues/76352 for helping catch this.
### Testing
```cmd
x.py test --stage 1 src/tools/tidy
x.py test --stage 1 --build x86_64-pc-windows-msvc src\test\debuginfo
```
remove public visibility previously needed for rustfmt
`submod_path_from_attr` in rustc_expand::module was previously public because it was also consumed by rustfmt. However, we've done a bit of refactoring in rustfmt and no longer need to use this function.
This changes the visibility to the parent mod as was originally going to be done before the rustfmt dependency was realized (c189565edc (diff-cd1b379893bae95f7991d5a3f3c6d337R201))
Add rust-dev component to support rustc development
This is preparatory work for permitting rustc developers to use CI-built LLVM rather than building it locally. Unlike distro-built LLVM, CI built LLVM is essentially guaranteed to behave perfectly for local development -- it is fully up to date, and carries all necessary patches.
This is a separate PR from #76349 because it needs to land before that one, since we want a master build with the full CI LLVM to be available for easier testing.
Make bootstrap build on beta
This is generally a good idea, and will help with being able to build bootstrap
without Python over time as it means we can "just" build with cargo +beta build
rather than needing the user to set environment variables. This is a minor step,
but a necessary one on that road.
r? `@jyn514`
Do not promote &mut of a non-ZST ever
Since ~pre-1.0~ 1.36, we have accepted code like this:
```rust
static mut TEST: &'static mut [i32] = {
let x = &mut [1,2,3];
x
};
```
I tracked it back to https://github.com/rust-lang/rust/pull/21744, but unfortunately could not find any discussion or RFC that would explain why we thought this was a good idea. And it's not, it breaks all sorts of things -- see https://github.com/rust-lang/rust/issues/75556.
To fix https://github.com/rust-lang/rust/issues/75556, we have to stop promoting non-ZST mutable references no matter the context, which is what this PR does. It's a breaking change.
Notice that this still works, since it does not rely on promotion:
```rust
static mut TEST: &'static mut [i32] = &mut [0,1,2];
```
Cc `@rust-lang/wg-const-eval`
Tracing update
This does not bring the more significant changes that are coming down the pipeline, but since I've already prepared the PR leaving it up :)
See https://github.com/rust-lang/rust/pull/76210#issuecomment-685065938:
> Unfortunately, tracing 0.1.20 — which contained the change to reduce the amount of code generated by the tracing macros — had to be yanked, as it broke previously-compiling code for some downstream crates. I've not yet had the chance to fix this and release a new patch. So, in order to benefit from the changes to reduce generated code, you'll need to wait until there's a new version of tracing as well as tracing-attributes and tracing-core.
Add derive macro for specifying diagnostics using attributes.
Introduces `#[derive(SessionDiagnostic)]`, a derive macro for specifying structs that can be converted to Diagnostics using directions given by attributes on the struct and its fields. Currently, the following attributes have been implemented:
- `#[code = "..."]` -- this sets the Diagnostic's error code, and must be provided on the struct iself (ie, not on a field). Equivalent to calling `code`.
- `#[message = "..."]` -- this sets the Diagnostic's primary error message.
- `#[label = "..."]` -- this must be applied to fields of type `Span`, and is equivalent to `span_label`
- `#[suggestion(..)]` -- this allows a suggestion message to be supplied. This attribute must be applied to a field of type `Span` or `(Span, Applicability)`, and is equivalent to calling `span_suggestion`. Valid arguments are:
- `message = "..."` -- this sets the suggestion message.
- (Optional) `code = "..."` -- this suggests code for the suggestion. Defaults to empty.
`suggestion`also comes with other variants: `#[suggestion_short(..)]`, `#[suggestion_hidden(..)]` and `#[suggestion_verbose(..)]` which all take the same keys.
Within the strings passed to each attribute, fields can be referenced without needing to be passed explicitly into the format string -- eg, `#[error = "{ident} already declared"] ` will set the error message to `format!("{} already declared", &self.ident)`. Any fields on the struct can be referenced in this way.
Additionally, for any of these attributes, Option fields can be used to only optionally apply the decoration -- for example:
```rust
#[derive(SessionDiagnostic)]
#[code = "E0123"]
struct SomeKindOfError {
...
#[suggestion(message = "informative error message")]
opt_sugg: Option<(Span, Applicability)>
...
}
```
will not emit a suggestion if `opt_sugg` is `None`.
We plan on iterating on this macro further; this PR is a start.
Closes#61132.
r? `@oli-obk`
Support dataflow problems on arbitrary lattices
This PR implements last of the proposed extensions I mentioned in the design meeting for the original dataflow refactor. It extends the current dataflow framework to work with arbitrary lattices, not just `BitSet`s. This is a prerequisite for dataflow-enabled MIR const-propagation. Personally, I am skeptical of the usefulness of doing const-propagation pre-monomorphization, since many useful constants only become known after monomorphization (e.g. `size_of::<T>()`) and users have a natural tendency to hand-optimize the rest. It's probably worth exprimenting with, however, and others have shown interest cc `@rust-lang/wg-mir-opt.`
The `Idx` associated type is moved from `AnalysisDomain` to `GenKillAnalysis` and replaced with an associated `Domain` type that must implement `JoinSemiLattice`. Like before, each `Analysis` defines the "bottom value" for its domain, but can no longer override the dataflow join operator. Analyses that want to use set intersection must now use the `lattice::Dual` newtype. `GenKillAnalysis` impls have an additional requirement that `Self::Domain: BorrowMut<BitSet<Self::Idx>>`, which effectively means that they must use `BitSet<Self::Idx>` or `lattice::Dual<BitSet<Self::Idx>>` as their domain.
Most of these changes were mechanical. However, because a `Domain` is no longer always a powerset of some index type, we can no longer use an `IndexVec<BasicBlock, GenKillSet<A::Idx>>>` to store cached block transfer functions. Instead, we use a boxed `dyn Fn` trait object. I discuss a few alternatives to the current approach in a commit message.
The majority of new lines of code are to preserve existing Graphviz diagrams for those unlucky enough to have to debug dataflow analyses. I find these diagrams incredibly useful when things are going wrong and considered regressing them unacceptable, especially the pretty-printing of `MovePathIndex`s, which are used in many dataflow analyses. This required a parallel `fmt` trait used only for printing dataflow domains, as well as a refactoring of the `graphviz` module now that we cannot expect the domain to be a `BitSet`. Some features did have to be removed, such as the gen/kill display mode (which I didn't use but existed to mirror the output of the old dataflow framework) and line wrapping. Since I had to rewrite much of it anyway, I took the opportunity to switch to a `Visitor` for printing dataflow state diffs instead of using cursors, which are error prone for code that must be generic over both forward and backward analyses. As a side-effect of this change, we no longer have quadratic behavior when writing graphviz diagrams for backward dataflow analyses.
r? `@pnkfelix`
This currently includes libLLVM, llvm-config, and FileCheck, but will perhaps
expand to more tooling overtime. It should be considered entirely unstable and
may change at any time.
Implement Seek::stream_position() for BufReader
Optimization over `BufReader::seek()` for getting the current position without flushing the internal buffer.
Related to #31100. Based on the code in #70577.
