Recover `mut $pat` and other improvements #63945

Centril · 2019-08-27T11:12:46Z

Recover on e.g. mut Foo(x, y) and suggest Foo(mut x, mut y). Fixes Custom diagnostic for bad mut in pattern with sub-bindings #63764.
Recover on e.g. let mut mut x;
Recover on e.g. let keyword and let keyword(...).
Cleanups in token.rs with fn is_non_raw_ident_where and friends.

rust-highfive · 2019-08-27T11:12:51Z

r? @eddyb

(rust_highfive has picked a reviewer for you, use r? to override)

Centril · 2019-08-27T11:12:57Z

r? @estebank

src/libsyntax/parse/parser/pat.rs

Centril · 2019-08-27T17:56:09Z

This turned out to add quite a bit of additional logic but I think it's a working implementation.
cc also @petrochenkov

Centril · 2019-08-27T18:00:12Z

src/libsyntax/parse/parser/pat.rs

+        AddMut.visit_pat(&mut pat);
+
+        // Unwrap; If we don't have `mut $ident`, error.
+        let pat = pat.into_inner();


We could avoid this allocation by extracting a new function fn parse_pat_with_range_pat_kind. This would also avoid the need for the NtPat logic above but it would also not recover on let mut $p where $p:pat.

src/test/ui/parser/issue-32501.stderr

estebank · 2019-08-27T18:55:06Z

src/test/ui/parser/keyword-pub-as-identifier.rs


 fn main() {
-    let pub = "foo"; //~ error: expected pattern, found keyword `pub`
+    let pub = "foo"; //~ error: expected identifier, found keyword `pub`


I think all of these tests could be one file, don't you think? (not to be addressed in this PR necessarily)

Want to file a follow up issue?

src/test/ui/self/self_type_keyword.stderr

src/test/ui/self/self_type_keyword.rs

estebank · 2019-08-27T19:03:21Z

src/libsyntax/parse/parser/pat.rs

+        self.check_path()
+        // Just for recovery (see `can_be_ident`).
+        || self.token.is_ident() && !self.token.is_bool_lit() && !self.token.is_keyword(kw::In)
+    }


Looking at this made me realize that we should have some check for "expected Fn() -> _, found bool and expr is foo\n|| bar" to detect a missing ; on the first pattern and returning a closure was intended 😬

What would be a concrete example of a pitfall here? I'd like to avoid complicating things until someone reports a an issue.

src/libsyntax/parse/parser/pat.rs

estebank

LGTM, but I'd like to handle the _ and Self cases as well to avoid being misleading (don't add or change the suggestion in those two cases). r=me

Centril · 2019-08-27T21:54:47Z

@estebank I made some more changes; can you have another quick look at the code?

estebank · 2019-08-27T21:55:04Z

@bors r+

bors · 2019-08-27T21:55:08Z

📌 Commit 42e895d has been approved by estebank

Recover `mut $pat` and other improvements - Recover on e.g. `mut Foo(x, y)` and suggest `Foo(mut x, mut y)`. Fixes rust-lang#63764. - Recover on e.g. `let mut mut x;` - Recover on e.g. `let keyword` and `let keyword(...)`. - Cleanups in `token.rs` with `fn is_non_raw_ident_where` and friends.

@ghost

Rollup of 11 pull requests Successful merges: - #63811 (Correctly suggest adding bounds to `impl Trait` argument) - #63933 (Resolve some small issues related to #63580) - #63938 (or-pattern: fix typo in error message) - #63945 (Recover `mut $pat` and other improvements) - #63958 (const_prop: only call error_to_const_error if we are actually showing something) - #63961 (Add Option<Span> to `require_lang_item`) - #63963 (remove the reference to __cxa_thread_atexit_impl) - #63965 (Prevent syntax error in LD linker version script) - #63968 (rustc_apfloat: make the crate #![no_std] explicitly.) - #63970 (Notify me (flip1995) when Clippy toolstate changes) - #63980 (add missing `#[repr(C)]` on the Slices union) Failed merges: - #63989 (Add Yaah to clippy toolstain notification list) r? @ghost

Pkgsrc changes: * Remove patch which no longer applies (but what about RPATH?) * Adapt a few patches to changed files upstream. Upstream changes: Version 1.39.0 (2019-11-07) =========================== Language -------- - [You can now create `async` functions and blocks with `async fn`, `async move {}`, and `async {}` respectively, and you can now call `.await` on async expressions.][63209] - [You can now use certain attributes on function, closure, and function pointer parameters.][64010] These attributes include `cfg`, `cfg_attr`, `allow`, `warn`, `deny`, `forbid` as well as inert helper attributes used by procedural macro attributes applied to items. e.g. ```rust fn len( #[cfg(windows)] slice: &[u16], #[cfg(not(windows))] slice: &[u8], ) -> usize { slice.len() } ``` - [You can now take shared references to bind-by-move patterns in the `if` guards of `match` arms.][63118] e.g. ```rust fn main() { let array: Box<[u8; 4]> = Box::new([1, 2, 3, 4]); match array { nums // ---- `nums` is bound by move. if nums.iter().sum::<u8>() == 10 // ^------ `.iter()` implicitly takes a reference to `nums`. => { drop(nums); // ----------- Legal as `nums` was bound by move and so we have ownership. } _ => unreachable!(), } } ``` Compiler -------- - [Added tier 3\* support for the `i686-unknown-uefi` target.][64334] - [Added tier 3 support for the `sparc64-unknown-openbsd` target.][63595] - [rustc will now trim code snippets in diagnostics to fit in your terminal.] [63402] **Note** Cargo currently doesn't use this feature. Refer to [cargo#7315][cargo/7315] to track this feature's progress. - [You can now pass `--show-output` argument to test binaries to print the output of successful tests.][62600] \* Refer to Rust's [platform support page][forge-platform-support] for more information on Rust's tiered platform support. Libraries --------- - [`Vec::new` and `String::new` are now `const` functions.][64028] - [`LinkedList::new` is now a `const` function.][63684] - [`str::len`, `[T]::len` and `str::as_bytes` are now `const` functions.][63770] - [The `abs`, `wrapping_abs`, and `overflowing_abs` numeric functions are now `const`.][63786] Stabilized APIs --------------- - [`Pin::into_inner`] - [`Instant::checked_duration_since`] - [`Instant::saturating_duration_since`] Cargo ----- - [You can now publish git dependencies if supplied with a `version`.] [cargo/7237] - [The `--all` flag has been renamed to `--workspace`.][cargo/7241] Using `--all` is now deprecated. Misc ---- - [You can now pass `-Clinker` to rustdoc to control the linker used for compiling doctests.][63834] Compatibility Notes ------------------- - [Code that was previously accepted by the old borrow checker, but rejected by the NLL borrow checker is now a hard error in Rust 2018.][63565] This was previously a warning, and will also become a hard error in the Rust 2015 edition in the 1.40.0 release. - [`rustdoc` now requires `rustc` to be installed and in the same directory to run tests.][63827] This should improve performance when running a large amount of doctests. - [The `try!` macro will now issue a deprecation warning.][62672] It is recommended to use the `?` operator instead. - [`asinh(-0.0)` now correctly returns `-0.0`.][63698] Previously this returned `0.0`. [62600]: rust-lang/rust#62600 [62672]: rust-lang/rust#62672 [63118]: rust-lang/rust#63118 [63209]: rust-lang/rust#63209 [63402]: rust-lang/rust#63402 [63565]: rust-lang/rust#63565 [63595]: rust-lang/rust#63595 [63684]: rust-lang/rust#63684 [63698]: rust-lang/rust#63698 [63770]: rust-lang/rust#63770 [63786]: rust-lang/rust#63786 [63827]: rust-lang/rust#63827 [63834]: rust-lang/rust#63834 [63927]: rust-lang/rust#63927 [63933]: rust-lang/rust#63933 [63934]: rust-lang/rust#63934 [63938]: rust-lang/rust#63938 [63940]: rust-lang/rust#63940 [63941]: rust-lang/rust#63941 [63945]: rust-lang/rust#63945 [64010]: rust-lang/rust#64010 [64028]: rust-lang/rust#64028 [64334]: rust-lang/rust#64334 [cargo/7237]: rust-lang/cargo#7237 [cargo/7241]: rust-lang/cargo#7241 [cargo/7315]: rust-lang/cargo#7315 [`Pin::into_inner`]: https://doc.rust-lang.org/std/pin/struct.Pin.html#method.into_inner [`Instant::checked_duration_since`]: https://doc.rust-lang.org/std/time/struct.Instant.html#method.checked_duration_since [`Instant::saturating_duration_since`]: https://doc.rust-lang.org/std/time/struct.Instant.html#method.saturating_duration_since

@matthewjasper

…stebank parse: recover `mut (x @ y)` as `(mut x @ mut y)`. Follow up to rust-lang#68992 (comment) and rust-lang#63945. Specifically, when given `let mut (x @ y)` we recover with `let (mut x @ mut y)` as the suggestion: ```rust error: `mut` must be attached to each individual binding --> $DIR/mut-patterns.rs:12:9 | LL | let mut (x @ y) = 0; | ^^^^^^^^^^^ help: add `mut` to each binding: `(mut x @ mut y)` | = note: `mut` may be followed by `variable` and `variable @ pattern` ``` r? @matthewjasper @estebank

Centril added 3 commits August 27, 2019 10:14

token: refactor with is_non_raw_ident_where.

5cc1559

Simplify with Symbol/Token::is_book_lit.

e49b958

recover on 'mut ' and improve recovery for keywords.

f908aa9

rust-highfive assigned eddyb Aug 27, 2019

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Aug 27, 2019

rust-highfive assigned estebank and unassigned eddyb Aug 27, 2019

Centril commented Aug 27, 2019

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Centril changed the title ~~Recover mut $pat and other improvements~~ [WIP] Recover mut $pat and other improvements Aug 27, 2019

Ensure 'let mut ;' where ':pat' is banned.

dbbe336

Centril changed the title ~~[WIP] Recover mut $pat and other improvements~~ Recover mut $pat and other improvements Aug 27, 2019

Centril commented Aug 27, 2019

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estebank reviewed Aug 27, 2019

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estebank reviewed Aug 27, 2019

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estebank reviewed Aug 27, 2019

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estebank approved these changes Aug 27, 2019

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Improve 'mut ' diagnostic.

42e895d

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Aug 27, 2019

Centril mentioned this pull request Aug 29, 2019

Rollup of 11 pull requests #63990

Merged

bors merged commit 42e895d into rust-lang:master Aug 29, 2019

Centril deleted the recover-mut-pat branch August 29, 2019 08:48

Centril mentioned this pull request Sep 28, 2019

RFC: mut (x, y, ..) and mut [x, y, ..] pattern shorthand rust-lang/rfcs#2401

Closed

Centril mentioned this pull request Feb 17, 2020

parse: recover mut (x @ y) as (mut x @ mut y). #69236

Merged

Recover mut $pat and other improvements #63945

Recover mut $pat and other improvements #63945

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Recover `mut $pat` and other improvements #63945

Recover `mut $pat` and other improvements #63945

Centril commented Aug 27, 2019 •

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