Fix redundant semicolon lint interaction with proc macro attributes
Fixes#63967 and fixes#63947, both of which were caused by the lint's changes to the parser interacting poorly with proc macro attributes and causing span information to be lost
r? @varkor
or-patterns: Push `PatKind/PatternKind::Or` at top level to HIR & HAIR
Following up on work in https://github.com/rust-lang/rust/pull/64111, https://github.com/rust-lang/rust/pull/63693, and https://github.com/rust-lang/rust/pull/61708, in this PR:
- We change `hair::Arm.patterns: Vec<Pattern<'_>>` into `hir::Arm.pattern: Pattern<'_>`.
- `fn hair::Arm::top_pats_hack` is introduced as a temporary crutch in MIR building to avoid more changes.
- We change `hir::Arm.pats: HirVec<P<Pat>>` into `hir::Arm.pat: P<Pat>`.
- The hacks in `rustc::hir::lowering` are removed since the representation hack is no longer necessary.
- In some places, `fn hir::Arm::top_pats_hack` is introduced to leave some things as future work.
- Misc changes: HIR pretty printing is adjusted to behave uniformly wrt. top/inner levels, rvalue promotion is adjusted, regionck, and dead_code is also.
- Type checking is adjusted to uniformly handle or-patterns at top/inner levels.
To make things compile, `p_0 | ... | p_n` is redefined as a "reference pattern" in [`fn is_non_ref_pat`](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_typeck/check/struct.FnCtxt.html#method.is_non_ref_pat) for now. This is done so that reference types are not eagerly stripped from the `expected: Ty<'tcx>`.
- Liveness is adjusted wrt. the `unused_variables` and `unused_assignments` lints to handle top/inner levels uniformly and the handling of `fn` parameters, `let` locals, and `match` arms are unified in this respect. This is not tested for now as exhaustiveness checks are reachable and will ICE.
- In `check_match`, checking `@` and by-move bindings is adjusted. However, exhaustiveness checking is not adjusted the moment and is handled by @dlrobertson in https://github.com/rust-lang/rust/pull/63688.
- AST borrowck (`construct.rs`) is not adjusted as AST borrowck will be removed soon.
r? @matthewjasper
cc @dlrobertson @varkor @oli-obk
Stabilize `param_attrs` in Rust 1.39.0
# Stabilization proposal
I propose that we stabilize `#![feature(param_attrs)]`.
Tracking issue: #60406
Version: 1.39 (2019-09-26 => beta, 2019-11-07 => stable).
## What is stabilized
It is now possible to add outer attributes like `#[cfg(..)]` on formal parameters of functions, closures, and function pointer types. For example:
```rust
fn len(
#[cfg(windows)] slice: &[u16],
#[cfg(not(windows))] slice: &[u8],
) -> usize {
slice.len()
}
```
## What isn't stabilized
* Documentation comments like `/// Doc` on parameters.
* Code expansion of a user-defined `#[proc_macro_attribute]` macro used on parameters.
* Built-in attributes other than `cfg`, `cfg_attr`, `allow`, `warn`, `deny`, and `forbid`. Currently, only the lints `unused_variables` and `unused_mut` have effect and may be controlled on parameters.
## Motivation
The chief motivations for stabilizing `param_attrs` include:
* Finer conditional compilation with `#[cfg(..)]` and linting control of variables.
* Richer macro DSLs created by users.
* External tools and compiler internals can take advantage of the additional information that the parameters provide.
For more examples, see the [RFC][rfc motivation].
## Reference guide
In the grammar of function and function pointer, the grammar of variadic tails (`...`) and parameters are changed respectively from:
```rust
FnParam = { pat:Pat ":" }? ty:Type;
VaradicTail = "...";
```
into:
```rust
FnParam = OuterAttr* { pat:Pat ":" }? ty:Type;
VaradicTail = OuterAttr* "...";
```
The grammar of a closure parameter is changed from:
```rust
ClosureParam = pat:Pat { ":" ty:Type }?;
```
into:
```rust
ClosureParam = OuterAttr* pat:Pat { ":" ty:Type }?;
```
More generally, where there's a list of formal (value) parameters separated or terminated by `,` and delimited by `(` and `)`. Each parameter in that list may optionally be prefixed by `OuterAttr+`.
Note that in all cases, `OuterAttr*` applies to the whole parameter and not just the pattern. This distinction matters in pretty printing and in turn for macros.
## History
* On 2018-10-15, @Robbepop proposes [RFC 2565][rfc], "Attributes in formal function parameter position".
* On 2019-04-30, [RFC 2565][rfc] is merged and the tracking issue is made.
* On 2019-06-12, a partial implementation was completed. The implementation was done in [#60669][60669] by @c410-f3r and the PR was reviewed by @petrochenkov and @Centril.
* On 2019-07-29, [#61238][61238] was fixed in [#61856][61856]. The issue fixed was that lint attributes on function args had no effect. The PR was written by @c410-f3r and reviewed by @matthewjasper, @petrochenkov, and @oli-obk.
* On 2019-08-02, a bug [#63210][63210] was filed wherein the attributes on formal parameters would not be passed to macros. The issue was about forgetting to call the relevant method in `fn print_arg` in the pretty printer. In [#63212][63212], written by @Centril on 2019-08-02 and reviewed by @davidtwco, the issue aforementioned was fixed.
* This PR stabilizes `param_attrs`.
## Tests
* [On Rust 2018, attributes aren't permitted on function parameters without a pattern in trait definitions.](https://github.com/rust-lang/rust/blob/master/src/test/ui/rfc-2565-param-attrs/param-attrs-2018.rs)
* [All attributes that should be allowed. This includes `cfg`, `cfg_attr`, and lints check attributes.](https://github.com/rust-lang/rust/blob/master/src/test/ui/rfc-2565-param-attrs/param-attrs-allowed.rs)
* [Built-in attributes, which should be forbidden, e.g., `#[test]`, are.](https://github.com/rust-lang/rust/blob/master/src/test/ui/rfc-2565-param-attrs/param-attrs-builtin-attrs.rs)
* [`cfg` and `cfg_attr` are properly evaluated.](https://github.com/rust-lang/rust/blob/master/src/test/ui/rfc-2565-param-attrs/param-attrs-cfg.rs)
* [`unused_mut`](46f405ec4d/src/test/ui/rfc-2565-param-attrs/param-attrs-cfg.rs) and [`unused_variables`](https://github.com/rust-lang/rust/blob/master/src/test/ui/lint/lint-unused-variables.rs) are correctly applied to parameter patterns.
* [Pretty printing takes formal parameter attributes into account.](https://github.com/rust-lang/rust/blob/master/src/test/ui/rfc-2565-param-attrs/param-attrs-pretty.rs)
## Possible future work
* Custom attributes inside function parameters aren't currently supported but it is something being worked on internally.
* Since documentation comments are syntactic sugar for `#[doc(...)]`, it is possible to allow literal `/// Foo` comments on function parameters.
[rfc motivation]: https://github.com/rust-lang/rfcs/blob/master/text/2565-formal-function-parameter-attributes.md#motivation
[rfc]: https://github.com/rust-lang/rfcs/pull/2565
[60669]: https://github.com/rust-lang/rust/pull/60669
[61856]: https://github.com/rust-lang/rust/pull/61856
[63210]: https://github.com/rust-lang/rust/issues/63210
[61238]: https://github.com/rust-lang/rust/issues/61238
[63212]: https://github.com/rust-lang/rust/pull/63212
This report is a collaborative work with @Centril.
Fixes#64590
When we emit an 'unreachable' lint, we now add a note pointing at the
expression that actually causes the code to be unreachable (e.g.
`return`, `break`, `panic`).
This is especially useful when macros are involved, since a diverging
expression might be hidden inside of a macro invocation.
This is not perfectly correct as `#[attr] (5)` will still not lint, but
it does seem good enough, in particular as the parentheses in that case
are not unambiguously incorrect.
rustc: Stabilize options for pipelined compilation
This commit stabilizes options in the compiler necessary for Cargo to
enable "pipelined compilation" by default. The concept of pipelined
compilation, how it's implemented, and what it means for rustc are
documented in #60988. This PR is coupled with a PR against Cargo
(rust-lang/cargo#7143) which updates Cargo's support for pipelined
compliation to rustc, and also enables support by default in Cargo.
(note that the Cargo PR cannot land until this one against rustc lands).
The technical changes performed here were to stabilize the functionality
proposed in #60419 and #60987, the underlying pieces to enable pipelined
compilation support in Cargo. The issues have had some discussion during
stabilization, but the newly stabilized surface area here is:
* A new `--json` flag was added to the compiler.
* The `--json` flag can be passed multiple times.
* The value of the `--json` flag is a comma-separated list of
directives.
* The `--json` flag cannot be combined with `--color`
* The `--json` flag must be combined with `--error-format=json`
* The acceptable list of directives to `--json` are:
* `diagnostic-short` - the `rendered` field of diagnostics will have a
"short" rendering matching `--error-format=short`
* `diagnostic-rendered-ansi` - the `rendered` field of diagnostics
will be colorized with ansi color codes embedded in the string field
* `artifacts` - JSON blobs will be emitted for artifacts being emitted
by the compiler
The unstable `-Z emit-artifact-notifications` and `--json-rendered`
flags have also been removed during this commit as well.
Closes#60419Closes#60987Closes#60988
Rollup of 8 pull requests
Successful merges:
- #61856 (Lint attributes on function arguments)
- #62360 (Document that ManuallyDrop::drop should not called more than once)
- #62392 (Update minifier-rs version)
- #62871 (Explicit error message for async recursion.)
- #62995 (Avoid ICE when suggestion span is at Eof)
- #63053 (SystemTime docs: recommend Instant for elapsed time)
- #63081 (tidy: Cleanup the directory whitelist)
- #63088 (Remove anonymous_parameters from unrelated test)
Failed merges:
r? @ghost
