Improve formatting of doc code blocks
We don't currently apply automatic formatting to doc comment code blocks. As a
result, it has built up various idiosyncracies, which make such automatic
formatting difficult. Some of those idiosyncracies also make things harder for
human readers or other tools.
This PR makes a few improvements to doc code formatting, in the hopes of making
future automatic formatting easier, as well as in many cases providing net
readability improvements.
I would suggest reading each commit separately, as each commit contains one
class of changes.
These examples feature Rust code that's presented primarily to
illustrate how its compilation would be handled, and these examples are
formatted to highlight those aspects in ways that rustfmt wouldn't
preserve. Turn formatting off in those examples.
(Doc code isn't formatted yet, but this will make it easier to enable
doc code formatting in the future.)
Fix a mix-up of a block with its predecessors in handling of SwitchInt
edge effects for backward analysis. Note that this functionality is
currently unused, so change has no practical impact.
Apply effects to `otherwise` edge in dataflow analysis
This allows `ElaborateDrops` to remove drops when a `match` wildcard arm covers multiple no-Drop enum variants. It modifies dataflow analysis to update the `MaybeUninitializedPlaces` and `MaybeInitializedPlaces` data for a block reached through an `otherwise` edge.
Fixesrust-lang/rust#142705.
Separate dataflow analysis and results
`Analysis` gets put into `Results` with `EntryStates`, by `iterate_to_fixpoint`. This has two problems:
- `Results` is passed various places where only `Analysis` is needed.
- `EntryStates` is passed around mutably everywhere even though it is immutable.
This commit mostly separates `Analysis` from `Results` and fixes these two problems.
r? `@davidtwco`
Make #![feature(let_chains)] bootstrap conditional in compiler/
Let chains have been stabilized recently in #132833, so we can remove the gating from our uses in the compiler (as the compiler uses edition 2024).
`Results` contains and `Analysis` and an `EntryStates`. The unfortunate
thing about this is that the analysis needs to be mutable everywhere
(`&mut Analysis`) which forces the `Results` to be mutable everywhere,
even though `EntryStates` is immutable everywhere.
To fix this, this commit renames `Results` as `AnalysisAndResults`,
renames `EntryStates` as `Results`, and separates the analysis and
results as much as possible. (`AnalysisAndResults` doesn't get much use,
it's mostly there to facilitate method chaining of
`iterate_to_fixpoint`.)
`Results` is immutable everywhere, which:
- is a bit clearer on how the data is used,
- avoids an unnecessary clone of entry states in
`locals_live_across_suspend_points`, and
- moves the results outside the `RefCell` in Formatter.
The commit also reformulates `ResultsHandle` as the generic `CowMut`,
which is simpler than `ResultsHandle` because it doesn't need the
`'tcx` lifetime and the trait bounds. It also which sits nicely
alongside the new use of `Cow` in `ResultsCursor`.
Currently the graphviz code does a `results.visit_with` call while also
holding a `ResultsCursor` on the `results`. That is both kinds of
results traversals at the same time, which is awkward. This commit moves
the `results.visit_with` part earlier so the two results traversals
don't overlap.
Instead of `ResultsCursor`.
This partly undoes the second commit from #132346; possible because
`Results::as_result_cursor` (which doesn't consume the `Results`) is now
available. Delaying the `ResultsCursor` construction will facilitate the
next couple of commits.
I'm removing empty identifiers everywhere, because in practice they
always mean "no identifier" rather than "empty identifier". (An empty
identifier is impossible.) It's better to use `Option` to mean "no
identifier" because you then can't forget about the "no identifier"
possibility.
Some specifics:
- When testing an attribute for a single name, the commit uses the
`has_name` method.
- When testing an attribute for multiple names, the commit uses the new
`has_any_name` method.
- When using `match` on an attribute, the match arms now have `Some` on
them.
In the tests, we now avoid printing empty identifiers by not printing
the identifier in the `error:` line at all, instead letting the carets
point out the problem.
Revert <https://github.com/rust-lang/rust/pull/138084> to buy time to
consider options that avoids breaking downstream usages of cargo on
distributed `rustc-src` artifacts, where such cargo invocations fail due
to inability to inherit `lints` from workspace root manifest's
`workspace.lints` (this is only valid for the source rust-lang/rust
workspace, but not really the distributed `rustc-src` artifacts).
This breakage was reported in
<https://github.com/rust-lang/rust/issues/138304>.
This reverts commit 48caf81484b50dca5a5cebb614899a3df81ca898, reversing
changes made to c6662879b27f5161e95f39395e3c9513a7b97028.
By naming them in `[workspace.lints.rust]` in the top-level
`Cargo.toml`, and then making all `compiler/` crates inherit them with
`[lints] workspace = true`. (I omitted `rustc_codegen_{cranelift,gcc}`,
because they're a bit different.)
The advantages of this over the current approach:
- It uses a standard Cargo feature, rather than special handling in
bootstrap. So, easier to understand, and less likely to get
accidentally broken in the future.
- It works for proc macro crates.
It's a shame it doesn't work for rustc-specific lints, as the comments
explain.
Remove `rustc_middle::mir::tcx` module.
This is a really weird module. For example, what does `tcx` in `rustc_middle::mir::tcx::PlaceTy` mean? The answer is "not much".
The top-level module comment says:
> Methods for the various MIR types. These are intended for use after
> building is complete.
Awfully broad for a module that has a handful of impl blocks for some MIR types, none of which really relates to `TyCtxt`. `git blame` indicates the comment is ancient, from 2015, and made sense then.
This module is now vestigial. This commit removes it and moves all the code within into `rustc_middle::mir::statement`. Some specifics:
- `Place`, `PlaceRef`, `Rvalue`, `Operand`, `BorrowKind`: they all have `impl` blocks in both the `tcx` and `statement` modules. The commit merges the former into the latter.
- `BinOp`, `UnOp`: they only have `impl` blocks in `tcx`. The commit moves these into `statement`.
- `PlaceTy`, `RvalueInitializationState`: they are defined in `tcx`. This commit moves them into `statement` *and* makes them available in `mir::*`, like many other MIR types.
r? `@tmandry`
This is a really weird module. For example, what does `tcx` in
`rustc_middle::mir::tcx::PlaceTy` mean? The answer is "not much".
The top-level module comment says:
> Methods for the various MIR types. These are intended for use after
> building is complete.
Awfully broad for a module that has a handful of impl blocks for some
MIR types, none of which really relates to `TyCtxt`. `git blame`
indicates the comment is ancient, from 2015, and made sense then.
This module is now vestigial. This commit removes it and moves all the
code within into `rustc_middle::mir::statement`. Some specifics:
- `Place`, `PlaceRef`, `Rvalue`, `Operand`, `BorrowKind`: they all have `impl`
blocks in both the `tcx` and `statement` modules. The commit merges
the former into the latter.
- `BinOp`, `UnOp`: they only have `impl` blocks in `tcx`. The commit
moves these into `statement`.
- `PlaceTy`, `RvalueInitializationState`: they are defined in `tcx`.
This commit moves them into `statement` *and* makes them available in
`mir::*`, like many other MIR types.
`rustc_mir_dataflow/src/elaborate_drops.rs` contains some infrastructure
used by a few MIR passes: the `elaborate_drop` function, the
`DropElaborator` trait, etc.
`rustc_mir_transform/src/elaborate_drops.rs` (same file name, different
crate) contains the `ElaborateDrops` pass. It relies on a lot of the
infrastructure from `rustc_mir_dataflow/src/elaborate_drops.rs`.
It turns out that the drop infrastructure is only used in
`rustc_mir_transform`, so this commit moves it there. (The only
exception is the small `DropFlagState` type, which is moved to the
existing `rustc_mir_dataflow/src/drop_flag_effects.rs`.) The file is
renamed from `rustc_mir_dataflow/src/elaborate_drops.rs` to
`rustc_mir_transform/src/elaborate_drop.rs` (with no trailing `s`)
because (a) the `elaborate_drop` function is the most important export,
and (b) `rustc_mir_transform/src/elaborate_drops.rs` already exists.
All the infrastructure pieces that used to be `pub` are now
`pub(crate)`, because they are now only used within
`rustc_mir_transform`.
