Improve lifetime name annotations for closures & async functions #76468

SNCPlay42 · 2020-09-08T05:33:26Z

Don't refer to async functions as "generators" in error output
Where possible, emit annotations pointing exactly at the & in the return type of closures (when they have explicit return types) and async functions, like we do for arguments.
Addresses Error message in async fn refers to lifetime '1 without defining it #74072, but I wouldn't call that closed until annotations are identical for async and non-async functions.
Emit a better annotation when the lifetime doesn't appear in the full name type, which currently happens for opaque types like impl Future. Addresses Unclear lifetime error in closure producing a future #74497, but further improves could probably be made (why doesn't it appear in the type as impl Future + '1?)
This is included in the same PR because the changes to give_name_if_anonymous_region_appears_in_output would introduce ICE otherwise (it would return None in cases where it didn't previously, which then gets unwrapped)

rust-highfive · 2020-09-08T05:33:29Z

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

SNCPlay42 · 2020-09-08T05:35:58Z

compiler/rustc_mir/src/borrow_check/diagnostics/region_name.rs

+    /// returns the `i32`.
+    ///
+    /// [`OpaqueDef`]: hir::TyKind::OpaqueDef
+    fn get_future_inner_return_ty(&self, hir_ty: &'tcx hir::Ty<'tcx>) -> &'tcx hir::Ty<'tcx> {


Should this live somewhere more general, like on rustc_middle::hir::map::Map? Is it useful anywhere else?

#78755
This one is actually very close to the one in #76765, basically only differing in how we obtain the OpaqueDef that represents the Future that is the return type of the async fn

crlf0710 · 2020-09-25T13:49:30Z

r? @estebank

bors · 2020-09-26T20:07:52Z

☔ The latest upstream changes (presumably #77224) made this pull request unmergeable. Please resolve the merge conflicts.

Note that reviewers usually do not review pull requests until merge conflicts are resolved! Once you resolve the conflicts, you should change the labels applied by bors to indicate that your PR is ready for review. Post this as a comment to change the labels:

@rustbot modify labels: +S-waiting-on-review -S-waiting-on-author

bors · 2020-10-05T11:59:19Z

☔ The latest upstream changes (presumably #77552) made this pull request unmergeable. Please resolve the merge conflicts.

Note that reviewers usually do not review pull requests until merge conflicts are resolved! Once you resolve the conflicts, you should change the labels applied by bors to indicate that your PR is ready for review. Post this as a comment to change the labels:

@rustbot modify labels: +S-waiting-on-review -S-waiting-on-author

and give return of async fn a better span

Dylan-DPC-zz · 2020-10-08T00:45:15Z

~~@SNCPlay42 if you can resolve the new conflicts, we can get it reviewed after that to proceed with this~~

EDIT: ignore, didn't see the commit

Dylan-DPC-zz · 2020-10-08T00:46:54Z

@estebank this is ready for review

tmandry · 2020-10-20T17:23:16Z

Just to check, does this fix #75785?

SNCPlay42 · 2020-10-20T17:34:14Z

@tmandry no, this pr would change the output to what is shown in #75785 (comment) which still points at the wrong reference.

Dylan-DPC-zz · 2020-11-07T19:59:38Z

r? @Mark-Simulacrum

Mark-Simulacrum

r=me with nit fixed

compiler/rustc_mir/src/borrow_check/diagnostics/region_name.rs

SNCPlay42 · 2020-11-09T16:18:02Z

@rustbot modify labels: -S-waiting-on-author +S-waiting-on-review

Mark-Simulacrum · 2020-11-09T16:19:48Z

@bors r+ rollup

bors · 2020-11-09T16:19:50Z

📌 Commit 61b52a3 has been approved by Mark-Simulacrum

Rollup of 12 pull requests Successful merges: - rust-lang#74754 (Add `#[cfg(panic = '...')]`) - rust-lang#76468 (Improve lifetime name annotations for closures & async functions) - rust-lang#77016 (Test clippy on PR CI on changes) - rust-lang#78480 (BTreeMap: fix pointer provenance rules) - rust-lang#78502 (Update Chalk to 0.36.0) - rust-lang#78513 (Infer the default host target from the host toolchain if possible) - rust-lang#78566 (Enable LLVM Polly via llvm-args.) - rust-lang#78580 (inliner: Break inlining cycles) - rust-lang#78710 (rustc_ast: Do not panic by default when visiting macro calls) - rust-lang#78746 (Demote i686-unknown-freebsd to tier 2 compiler target) - rust-lang#78830 (fix `super_visit_with` for `Terminator`) - rust-lang#78844 (Monomorphize a type argument of size-of operation during codegen) Failed merges: r? `@ghost` `@rustbot` modify labels: rollup

rust-highfive assigned nikomatsakis Sep 8, 2020

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Sep 8, 2020

SNCPlay42 commented Sep 8, 2020

View reviewed changes

jyn514 added A-diagnostics Area: Messages for errors, warnings, and lints T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Sep 9, 2020

rust-highfive assigned estebank and unassigned nikomatsakis Sep 25, 2020

SNCPlay42 force-pushed the lifetime-names branch from b32d618 to 074d3e3 Compare September 26, 2020 20:31

SNCPlay42 added 2 commits October 5, 2020 14:01

don't refer to async as 'generators'

34ff352

and give return of async fn a better span

add RegionNameHighlight::Occluded

5042dbd

SNCPlay42 force-pushed the lifetime-names branch from 074d3e3 to faa241b Compare October 5, 2020 13:11

camelid added A-async-await Area: Async & Await A-closures Area: Closures (`|…| { … }`) labels Oct 7, 2020

Dylan-DPC-zz 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 Oct 8, 2020

Dylan-DPC-zz 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 Oct 8, 2020

camelid added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Nov 6, 2020

rust-highfive assigned Mark-Simulacrum and unassigned estebank Nov 7, 2020

Mark-Simulacrum reviewed Nov 8, 2020

View reviewed changes

compiler/rustc_mir/src/borrow_check/diagnostics/region_name.rs Outdated Show resolved Hide resolved

Mark-Simulacrum 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 Nov 8, 2020

use RegionNameHighlight for async fn and closure returns

61b52a3

SNCPlay42 force-pushed the lifetime-names branch from faa241b to 61b52a3 Compare November 9, 2020 16:16

rustbot 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 Nov 9, 2020

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 Nov 9, 2020

Dylan-DPC-zz mentioned this pull request Nov 9, 2020

Rollup of 12 pull requests #78904

Merged

bors merged commit 99f16e6 into rust-lang:master Nov 10, 2020

rustbot added this to the 1.49.0 milestone Nov 10, 2020

SNCPlay42 mentioned this pull request Dec 4, 2020

Prefer regions with an external_name in approx_universal_upper_bound #78164

Merged

tmandry mentioned this pull request Dec 17, 2020

Deduplicate code that finds the return type of a future #78755

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SNCPlay42 deleted the lifetime-names branch April 18, 2021 01:23

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Improve lifetime name annotations for closures & async functions #76468

Improve lifetime name annotations for closures & async functions #76468

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Improve lifetime name annotations for closures & async functions #76468

Improve lifetime name annotations for closures & async functions #76468

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