Change opaque type syntax from `existential type` to type alias `impl Trait` #63180

varkor · 2019-08-01T00:26:47Z

This implements a new feature gate type_alias_impl_trait (this is slightly different from the originally proposed feature name, but matches what has been used in discussion since), deprecating the old existential_types feature.

The syntax for opaque types has been changed. In addition, the "existential" terminology has been replaced with "opaque", as per previous discussion and the RFC.

This makes partial progress towards implementing #63063.

r? @Centril

varkor · 2019-08-01T00:27:54Z

@bors p=5 (This bitrots quickly.)

alexreg · 2019-08-01T03:03:42Z

👍 on the rename. What remains after this?

Centril

r=me with review comments addressed

src/test/rustdoc-ui/coverage/traits.rs

src/test/ui/async-await/async-await.rs

src/libsyntax/parse/parser.rs

src/librustc/hir/check_attr.rs

src/librustc_typeck/outlives/implicit_infer.rs

src/libsyntax/print/pprust.rs

src/test/ui/issues/issue-60662.stdout

src/test/ui/traits/trait-bounds-in-arc.rs

src/test/ui/type-alias-impl-trait.rs

Centril · 2019-08-01T03:09:52Z

This implements a new feature gate type_alias_impl_trait (this is slightly different from the originally proposed feature name, but matches what has been used in discussion since), deprecating the old existential_types feature.

After merging, can you please change the tracking issue description + the F-* label name?

src/librustc/hir/print.rs

Centril · 2019-08-02T00:53:07Z

Changes look good.
r=me with the nit addressed. :)

varkor · 2019-08-02T02:40:42Z

@bors r=Centril

bors · 2019-08-02T02:40:43Z

📌 Commit 95cb30420c9f0928f1d116f54069308c3d9d0a75 has been approved by Centril

bors · 2019-08-02T05:39:42Z

⌛ Testing commit 95cb30420c9f0928f1d116f54069308c3d9d0a75 with merge 83de5034c67a36c99c643c1a148dd5ee1187cfc0...

bors · 2019-08-02T07:45:00Z

💔 Test failed - checks-azure

rust-highfive · 2019-08-02T07:45:01Z

The job x86_64-gnu-nopt of your PR failed (raw log). Through arcane magic we have determined that the following fragments from the build log may contain information about the problem.

Click to expand the log.

2019-08-02T05:41:19.0221244Z do so (now or later) by using -b with the checkout command again. Example:
2019-08-02T05:41:19.0223841Z 
2019-08-02T05:41:19.0227736Z   git checkout -b <new-branch-name>
2019-08-02T05:41:19.0229679Z 
2019-08-02T05:41:19.0232193Z HEAD is now at 83de5034c Auto merge of #63180 - varkor:trait-alias-impl-trait, r=Centril
2019-08-02T05:41:19.0364097Z ##[section]Starting: Collect CPU-usage statistics in the background
2019-08-02T05:41:19.0367187Z ==============================================================================
2019-08-02T05:41:19.0367272Z Task         : Bash
2019-08-02T05:41:19.0367347Z Description  : Run a Bash script on macOS, Linux, or Windows
---
2019-08-02T07:42:40.3616495Z 1 error: at least one trait must be specified
2019-08-02T07:42:40.3616884Z -   --> $DIR/generic_type_does_not_live_long_enough.rs:9:35
2019-08-02T07:42:40.3617154Z +   --> $DIR/generic_type_does_not_live_long_enough.rs:9:29
2019-08-02T07:42:40.3617222Z 3    |
2019-08-02T07:42:40.3617780Z - LL | existential type WrongGeneric<T>: 'static;
2019-08-02T07:42:40.3618079Z -    |                                   ^^^^^^^
2019-08-02T07:42:40.3618650Z + LL | type WrongGeneric<T> = impl 'static;
2019-08-02T07:42:40.3618820Z 6 
2019-08-02T07:42:40.3619054Z 7 error[E0308]: mismatched types
2019-08-02T07:42:40.3619413Z 8   --> $DIR/generic_type_does_not_live_long_enough.rs:6:18
2019-08-02T07:42:40.3619467Z 
2019-08-02T07:42:40.3619467Z 
2019-08-02T07:42:40.3619501Z 
2019-08-02T07:42:40.3619665Z The actual stderr differed from the expected stderr.
2019-08-02T07:42:40.3620116Z Actual stderr saved to /checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/type-alias-impl-trait/generic_type_does_not_live_long_enough.nll/generic_type_does_not_live_long_enough.nll.stderr
2019-08-02T07:42:40.3620457Z To update references, rerun the tests and pass the `--bless` flag
2019-08-02T07:42:40.3620812Z To only update this specific test, also pass `--test-args type-alias-impl-trait/generic_type_does_not_live_long_enough.rs`
2019-08-02T07:42:40.3620961Z error: 1 errors occurred comparing output.
2019-08-02T07:42:40.3621040Z status: exit code: 1
2019-08-02T07:42:40.3621040Z status: exit code: 1
2019-08-02T07:42:40.3622074Z command: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustc" "/checkout/src/test/ui/type-alias-impl-trait/generic_type_does_not_live_long_enough.rs" "-Zthreads=1" "--target=x86_64-unknown-linux-gnu" "--error-format" "json" "-Zui-testing" "-C" "prefer-dynamic" "--out-dir" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/type-alias-impl-trait/generic_type_does_not_live_long_enough.nll" "-Zborrowck=mir" "-Crpath" "-Cdebuginfo=0" "-Zunstable-options" "-Lnative=/checkout/obj/build/x86_64-unknown-linux-gnu/native/rust-test-helpers" "-L" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/type-alias-impl-trait/generic_type_does_not_live_long_enough.nll/auxiliary" "-A" "unused"
2019-08-02T07:42:40.3622617Z ------------------------------------------
2019-08-02T07:42:40.3622666Z 
2019-08-02T07:42:40.3622923Z ------------------------------------------
2019-08-02T07:42:40.3622990Z stderr:
2019-08-02T07:42:40.3622990Z stderr:
2019-08-02T07:42:40.3623523Z ------------------------------------------
2019-08-02T07:42:40.3623598Z error: at least one trait must be specified
2019-08-02T07:42:40.3623909Z   --> /checkout/src/test/ui/type-alias-impl-trait/generic_type_does_not_live_long_enough.rs:9:29
2019-08-02T07:42:40.3623990Z    |
2019-08-02T07:42:40.3624232Z LL | type WrongGeneric<T> = impl 'static;
2019-08-02T07:42:40.3624354Z 
2019-08-02T07:42:40.3624408Z error[E0308]: mismatched types
2019-08-02T07:42:40.3624711Z   --> /checkout/src/test/ui/type-alias-impl-trait/generic_type_does_not_live_long_enough.rs:6:18
2019-08-02T07:42:40.3624788Z    |
2019-08-02T07:42:40.3624788Z    |
2019-08-02T07:42:40.3624864Z LL |     let z: i32 = x; //~ ERROR mismatched types
2019-08-02T07:42:40.3624934Z    |                  ^ expected i32, found opaque type
2019-08-02T07:42:40.3625062Z    = note: expected type `i32`
2019-08-02T07:42:40.3625062Z    = note: expected type `i32`
2019-08-02T07:42:40.3625142Z               found type `WrongGeneric::<&{integer}>`
2019-08-02T07:42:40.3625383Z error: aborting due to 2 previous errors
2019-08-02T07:42:40.3625422Z 
2019-08-02T07:42:40.3625727Z For more information about this error, try `rustc --explain E0308`.
2019-08-02T07:42:40.3625795Z 
---
2019-08-02T07:42:40.3627187Z thread 'main' panicked at 'Some tests failed', src/tools/compiletest/src/main.rs:533:22
2019-08-02T07:42:40.3627270Z note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace.
2019-08-02T07:42:40.3627315Z 
2019-08-02T07:42:40.3627358Z 
2019-08-02T07:42:40.3629539Z command did not execute successfully: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0-tools-bin/compiletest" "--compile-lib-path" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib" "--run-lib-path" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib/rustlib/x86_64-unknown-linux-gnu/lib" "--rustc-path" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustc" "--src-base" "/checkout/src/test/ui" "--build-base" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui" "--stage-id" "stage2-x86_64-unknown-linux-gnu" "--mode" "ui" "--target" "x86_64-unknown-linux-gnu" "--host" "x86_64-unknown-linux-gnu" "--llvm-filecheck" "/checkout/obj/build/x86_64-unknown-linux-gnu/llvm/build/bin/FileCheck" "--host-rustcflags" "-Crpath -Cdebuginfo=0 -Zunstable-options  -Lnative=/checkout/obj/build/x86_64-unknown-linux-gnu/native/rust-test-helpers" "--target-rustcflags" "-Crpath -Cdebuginfo=0 -Zunstable-options  -Lnative=/checkout/obj/build/x86_64-unknown-linux-gnu/native/rust-test-helpers" "--docck-python" "/usr/bin/python2.7" "--lldb-python" "/usr/bin/python2.7" "--gdb" "/usr/bin/gdb" "--llvm-version" "9.0.0-rust-1.38.0-dev\n" "--cc" "" "--cxx" "" "--cflags" "" "--llvm-components" "" "--llvm-cxxflags" "" "--adb-path" "adb" "--adb-test-dir" "/data/tmp/work" "--android-cross-path" "" "--color" "always" "--compare-mode" "nll"
2019-08-02T07:42:40.3630166Z 
2019-08-02T07:42:40.3630219Z 
2019-08-02T07:42:40.3630286Z failed to run: /checkout/obj/build/bootstrap/debug/bootstrap test
2019-08-02T07:42:40.3630376Z Build completed unsuccessfully in 1:56:31
2019-08-02T07:42:40.3630376Z Build completed unsuccessfully in 1:56:31
2019-08-02T07:42:41.1250320Z ##[error]Bash exited with code '1'.
2019-08-02T07:42:41.1284824Z ##[section]Starting: Upload CPU usage statistics
2019-08-02T07:42:41.1292280Z ==============================================================================
2019-08-02T07:42:41.1292375Z Task         : Bash
2019-08-02T07:42:41.1292456Z Description  : Run a Bash script on macOS, Linux, or Windows

I'm a bot! I can only do what humans tell me to, so if this was not helpful or you have suggestions for improvements, please ping or otherwise contact @TimNN. (Feature Requests)

bors · 2019-08-03T02:21:30Z

⌛ Testing commit fbd7e0c with merge d727071...

@Centril

Change opaque type syntax from `existential type` to type alias `impl Trait` This implements a new feature gate `type_alias_impl_trait` (this is slightly different from the originally proposed feature name, but matches what has been used in discussion since), deprecating the old `existential_types` feature. The syntax for opaque types has been changed. In addition, the "existential" terminology has been replaced with "opaque", as per previous discussion and the RFC. This makes partial progress towards implementing #63063. r? @Centril

bors · 2019-08-03T06:03:34Z

☀️ Test successful - checks-azure
Approved by: Centril
Pushing d727071 to master...

Broken due to: * rust-lang/rust#63180 (`Existential` -> `OpaqueTy`) * rust-lang/rust#63121 (New fields for `FormatSpec`)

Rustup to latest rustc master Broken due to: * rust-lang/rust#63180 (`Existential` -> `OpaqueTy`) * rust-lang/rust#63121 (New fields for `FormatSpec`)

Rustup to latest rustc master Broken due to: changelog: none * rust-lang/rust#63180 (`Existential` -> `OpaqueTy`) * rust-lang/rust#63121 (New fields for `FormatSpec`)

Rustup to latest rustc master Broken due to: * rust-lang/rust#63180 (`Existential` -> `OpaqueTy`) * rust-lang/rust#63121 (New fields for `FormatSpec`) changelog: none

`existential_type` deprecated by rust-lang/rust#63180 in favour of `#![feature(type_alias_impl_trait)]`. This change updates the code to use the new syntax and the circle ci configuration.

…694) Merge pull request #694 existential_type deprecated by rust-lang/rust#63180 in favour of #![feature(type_alias_impl_trait)]. This change updates the code with the new (much better) syntax and the circle ci configuration (merge after image is built).

rust-highfive assigned Centril Aug 1, 2019

varkor force-pushed the trait-alias-impl-trait branch from 52d3e24 to 3adbffe Compare August 1, 2019 00:29

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varkor mentioned this pull request Aug 1, 2019

Investigate whether Ty and OpaqueTy can be merged #63204

Closed

varkor force-pushed the trait-alias-impl-trait branch from a3aa40b to b09e8bd Compare August 2, 2019 00:27

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varkor added 9 commits August 2, 2019 02:44

Switch existential_type to type_alias_impl_trait

87738fe

Update syntax in existing tests

fc48541

Replace "existential" by "opaque"

c28ce3e

Fix fallout after rebase

70c8839

Replace abstract type with type alias impl Trait

2777386

Replace exist_ty and ExistTy with opaque_ty and OpaqueTy

b4fe555

Rename OpaqueTyOrigin variants

16033d1

Resolve FIXME with async-await test

a45cde5

Address review comments

b049221

varkor force-pushed the trait-alias-impl-trait branch from b09e8bd to 95cb304 Compare August 2, 2019 02:40

bors added the S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. label Aug 2, 2019

bors mentioned this pull request Aug 2, 2019

Update Cargo.lock #61393

Merged

bors added the S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. label Aug 2, 2019

bors added the merged-by-bors This PR was explicitly merged by bors. label Aug 3, 2019

bors merged commit fbd7e0c into rust-lang:master Aug 3, 2019

This was referenced Aug 3, 2019

rustdoc: general cleanups #62955

Merged

Make "see issue" consistent #63008

Closed

Stabilize async_await in Rust 1.39.0 #63209

Merged

Rename ItemKind::Ty to ItemKind::TyAlias #63213

Merged

phansch added a commit to phansch/rust-clippy that referenced this pull request Aug 3, 2019

Rustup to latest rustc master

d61df4f

Broken due to: * rust-lang/rust#63180 (`Existential` -> `OpaqueTy`) * rust-lang/rust#63121 (New fields for `FormatSpec`)

phansch mentioned this pull request Aug 3, 2019

Rustup to latest rustc master rust-lang/rust-clippy#4328

Merged

Centril mentioned this pull request Aug 3, 2019

Tracking issue for RFC 2515, "Permit impl Trait in type aliases" #63063

Open

8 tasks

little-arhat mentioned this pull request Aug 4, 2019

"can't qualify macro invocation with pub" error can fire without any macro invocations #63255

Closed

This was referenced Aug 22, 2019

existential keyword support intellij-rust/intellij-rust#4267

Closed

(DNM) Update toolchain to nightly-2019-08-21 (existential_type deprecated) tari-project/tari#694

Merged

Centril mentioned this pull request Aug 26, 2019

Confusing error message with type unification of impl Traits #63167

Closed

bjorn3 mentioned this pull request Sep 29, 2019

Switch back to a generic BootInfoFrameAllocator as soon as type X = impl Trait is supported phil-opp/blog_os#671

Open

Centril added the F-type_alias_impl_trait `#[feature(type_alias_impl_trait)]` label Nov 10, 2019

chrissimpkins mentioned this pull request Feb 10, 2020

ICE with type_alias_impl_trait: errors selecting obligation during MIR typeck #63355

Closed

dtolnay mentioned this pull request Sep 4, 2021

Delete old 'existential type' provisional syntax dtolnay/syn#1061

Merged

traviscross mentioned this pull request Apr 2, 2023

TAIT defining scope options #107645

Open

matthiaskrgr mentioned this pull request Dec 25, 2023

ICE: ForeignItem(ForeignItem ... is not a valid scope for an opaque type item #119295

Closed

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Change opaque type syntax from `existential type` to type alias `impl Trait` #63180

Change opaque type syntax from `existential type` to type alias `impl Trait` #63180

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Change opaque type syntax from existential type to type alias impl Trait #63180

Change opaque type syntax from existential type to type alias impl Trait #63180

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Change opaque type syntax from `existential type` to type alias `impl Trait` #63180

Change opaque type syntax from `existential type` to type alias `impl Trait` #63180