Teach parser to understand fake anonymous enum syntax #106960

estebank · 2023-01-17T01:20:52Z

Parse Ty | OtherTy in function argument and return types.
Parse type ascription in top level patterns.

Minimally address #100741.

rustbot · 2023-01-17T01:20:57Z

r? @cjgillot

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rustbot · 2023-01-17T01:31:56Z

Some changes occurred in src/tools/rustfmt

cc @rust-lang/rustfmt

Parse `-> Ty | OtherTy`. Parse type ascription in top level patterns.

fmease · 2023-01-17T16:00:52Z

You should probably add a self.may_recover() somewhere (#103534). The following code no longer compiles in your patch as far as I can tell (I could be wrong though):

macro_rules! check {
    ($Z:ty) => { compile_error!("triggered"); };
    ($X:ty | $Y:ty) => { };
}

check! { i32 | u8 } // passes on stable & nightly

estebank · 2023-01-17T17:09:46Z

@fmease that code continues to compile successfully (because the new parsing only triggers explicitly on type params and return types and nothing else). Added it as a test, as well as another test for the macro in those positions to confirm that even then the new parsing doesn't trigger in the macro context.

cjgillot

The improvements to type ascription in patterns are great.

cjgillot · 2023-01-21T10:21:54Z

compiler/rustc_ast/src/ast.rs

@@ -2096,6 +2096,9 @@ pub enum TyKind {
    Err,
    /// Placeholder for a `va_list`.
    CVarArgs,
+    /// Placeholder for "anonymous enums", which don't exist, but keeping their
+    /// information around lets us produce better diagnostics.
+    AnonEnum(Vec<P<Ty>>),


While I generally encourage to add information to the AST for diagnostics, adding a variant that does not exist in the language seems a bit too far.
IIUC, this is only needed for pretty-printing. I couldn't see where it appears in ui tests. Why isn't the usual TyKind::Err sufficient?

I can avoid including this for the purposes of this PR, but I have a very early attempt at real support for anonymous enums 1) to have more info for more accurate suggestions in later stages, particularly to deduplicate them (thinking of declaring the same enum in multiple return types) in subsequent work, and 2) having an in-tree proof of concept of the actual feature to convince myself of whether a very restricted version of this would be possible. I can safely remove this from this PR.

Edit: took it out.

Maybe TyKind::Err could contain an enum with parsed invalid syntax, like

enum TyError { AnonEnum(Vec<P<Ty>>), Other, }

src/tools/rustfmt/src/types.rs

cjgillot · 2023-01-23T20:01:52Z

@bors r+

bors · 2023-01-23T20:01:55Z

📌 Commit 020cca8 has been approved by cjgillot

It is now in the queue for this repository.

Teach parser to understand fake anonymous enum syntax Parse `Ty | OtherTy` in function argument and return types. Parse type ascription in top level patterns. Minimally address rust-lang#100741.

…iaskrgr Rollup of 11 pull requests Successful merges: - rust-lang#106407 (Improve proc macro attribute diagnostics) - rust-lang#106960 (Teach parser to understand fake anonymous enum syntax) - rust-lang#107085 (Custom MIR: Support binary and unary operations) - rust-lang#107086 (Print PID holding bootstrap build lock on Linux) - rust-lang#107175 (Fix escaping inference var ICE in `point_at_expr_source_of_inferred_type`) - rust-lang#107204 (suggest qualifying bare associated constants) - rust-lang#107248 (abi: add AddressSpace field to Primitive::Pointer ) - rust-lang#107272 (Implement ObjectSafe and WF in the new solver) - rust-lang#107285 (Implement `Generator` and `Future` in the new solver) - rust-lang#107286 (ICE in new solver if we see an inference variable) - rust-lang#107313 (Add Style Team Triagebot config) Failed merges: r? `@ghost` `@rustbot` modify labels: rollup

…ambiguous, r=estebank Revert "Teach parser to understand fake anonymous enum syntax" and related commits anonymous enum types are currently ambiguous in positions like: * `|` operator: `a as fn() -> B | C` * closure args: `|_: as fn() -> A | B` I first tried to thread around `RecoverAnonEnum` into all these positions, but the resulting complexity in the compiler is IMO not worth it, or at least worth a bit more thinking time. In the mean time, let's revert this syntax for now, so we can go back to the drawing board. Fixes rust-lang#107461 cc: `@estebank` `@cjgillot` rust-lang#106960 --- ### Squashed revert commits: Revert "review comment: Remove AST AnonTy" This reverts commit 020cca8. Revert "Ensure macros are not affected" This reverts commit 12d18e4. Revert "Emit fewer errors on patterns with possible type ascription" This reverts commit c847a01. Revert "Teach parser to understand fake anonymous enum syntax" This reverts commit 2d82420.

…biguous, r=estebank Revert "Teach parser to understand fake anonymous enum syntax" and related commits anonymous enum types are currently ambiguous in positions like: * `|` operator: `a as fn() -> B | C` * closure args: `|_: as fn() -> A | B` I first tried to thread around `RecoverAnonEnum` into all these positions, but the resulting complexity in the compiler is IMO not worth it, or at least worth a bit more thinking time. In the mean time, let's revert this syntax for now, so we can go back to the drawing board. Fixes rust-lang#107461 cc: `@estebank` `@cjgillot` rust-lang#106960 --- ### Squashed revert commits: Revert "review comment: Remove AST AnonTy" This reverts commit 020cca8. Revert "Ensure macros are not affected" This reverts commit 12d18e4. Revert "Emit fewer errors on patterns with possible type ascription" This reverts commit c847a01. Revert "Teach parser to understand fake anonymous enum syntax" This reverts commit 2d82420.

…ler-errors Parse and recover from type ascription in patterns Reintroduce part of rust-lang#106960, which was reverted in rust-lang#107478. r? `@compiler-errors`

…iaskrgr Rollup of 11 pull requests Successful merges: - rust-lang#106407 (Improve proc macro attribute diagnostics) - rust-lang#106960 (Teach parser to understand fake anonymous enum syntax) - rust-lang#107085 (Custom MIR: Support binary and unary operations) - rust-lang#107086 (Print PID holding bootstrap build lock on Linux) - rust-lang#107175 (Fix escaping inference var ICE in `point_at_expr_source_of_inferred_type`) - rust-lang#107204 (suggest qualifying bare associated constants) - rust-lang#107248 (abi: add AddressSpace field to Primitive::Pointer ) - rust-lang#107272 (Implement ObjectSafe and WF in the new solver) - rust-lang#107285 (Implement `Generator` and `Future` in the new solver) - rust-lang#107286 (ICE in new solver if we see an inference variable) - rust-lang#107313 (Add Style Team Triagebot config) Failed merges: r? `@ghost` `@rustbot` modify labels: rollup

Teach parser to understand fake anonymous enum syntax Parse `Ty | OtherTy` in function argument and return types. Parse type ascription in top level patterns. Minimally address rust-lang#100741.

rustbot assigned cjgillot Jan 17, 2023

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Jan 17, 2023

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estebank force-pushed the parse-anon-enums branch from b64e455 to 3e53763 Compare January 17, 2023 01:31

estebank added 2 commits January 17, 2023 01:58

Teach parser to understand fake anonymous enum syntax

2d82420

Parse `-> Ty | OtherTy`. Parse type ascription in top level patterns.

Emit fewer errors on patterns with possible type ascription

c847a01

estebank force-pushed the parse-anon-enums branch from 71a2806 to c847a01 Compare January 17, 2023 01:58

Ensure macros are not affected

12d18e4

estebank force-pushed the parse-anon-enums branch from 89dfe4c to 12d18e4 Compare January 17, 2023 17:10

cjgillot reviewed Jan 21, 2023

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cjgillot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jan 21, 2023

estebank force-pushed the parse-anon-enums branch 2 times, most recently from 0a8fa43 to cfff2eb Compare January 23, 2023 14:32

estebank added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Jan 23, 2023

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ytmimi reviewed Jan 23, 2023

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src/tools/rustfmt/src/types.rs Outdated Show resolved Hide resolved

review comment: Remove AST AnonTy

020cca8

estebank force-pushed the parse-anon-enums branch from cfff2eb to 020cca8 Compare January 23, 2023 18:21

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 Jan 23, 2023

matthiaskrgr mentioned this pull request Jan 23, 2023

Rollup of 9 pull requests #107240

Closed

This was referenced Jan 25, 2023

Rollup of 9 pull requests #107311

Closed

Rollup of 11 pull requests #107314

Merged

bors merged commit ba928ba into rust-lang:master Jan 26, 2023

rustbot added this to the 1.69.0 milestone Jan 26, 2023

nicopap mentioned this pull request Jan 30, 2023

Closure with a typed function argument and top level struct constructor break in nightly #107461

Closed

compiler-errors mentioned this pull request Jan 30, 2023

Revert "Teach parser to understand fake anonymous enum syntax" and related commits #107478

Merged

estebank mentioned this pull request Feb 2, 2023

Parse and recover from type ascription in patterns #107602

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estebank deleted the parse-anon-enums branch November 9, 2023 05:12

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Teach parser to understand fake anonymous enum syntax #106960

Teach parser to understand fake anonymous enum syntax #106960

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Teach parser to understand fake anonymous enum syntax #106960

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