Implement associated existential types #52650

oli-obk · 2018-07-23T15:41:04Z

no idea if these work with generic traits. I'm going home for the day 🤣

rust-highfive · 2018-07-23T15:56:05Z

The job x86_64-gnu-llvm-5.0 of your PR failed on Travis (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.


[00:04:02] travis_fold:start:tidy
travis_time:start:tidy
tidy check
[00:04:02] tidy error: /checkout/src/librustc/infer/anon_types/mod.rs:699: line longer than 100 chars
[00:04:04] some tidy checks failed
[00:04:04] 
[00:04:04] 
[00:04:04] command did not execute successfully: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0-tools-bin/tidy" "/checkout/src" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0/bin/cargo" "--no-vendor" "--quiet"
[00:04:04] 
[00:04:04] 
[00:04:04] failed to run: /checkout/obj/build/bootstrap/debug/bootstrap test src/tools/tidy
[00:04:04] Build completed unsuccessfully in 0:00:52
[00:04:04] Build completed unsuccessfully in 0:00:52
[00:04:04] make: *** [tidy] Error 1
[00:04:04] Makefile:79: recipe for target 'tidy' failed

The command "stamp sh -x -c "$RUN_SCRIPT"" exited with 2.
travis_time:start:00d0eb38
$ date && (curl -fs --head https://google.com | grep ^Date: | sed 's/Date: //g' || true)
---
travis_time:end:1cc6f580:start=1532360864400677917,finish=1532360864413079365,duration=12401448
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$ ln -s . checkout && for CORE in obj/cores/core.*; do EXE=$(echo $CORE | sed 's|obj/cores/core\.[0-9]*\.!checkout!\(.*\)|\1|;y|!|/|'); if [ -f "$EXE" ]; then printf travis_fold":start:crashlog\n\033[31;1m%s\033[0m\n" "$CORE"; gdb -q -c "$CORE" "$EXE" -iex 'set auto-load off' -iex 'dir src/' -iex 'set sysroot .' -ex bt -ex q; echo travis_fold":"end:crashlog; fi; done || true
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$ cat ./obj/build/x86_64-unknown-linux-gnu/native/asan/build/lib/asan/clang_rt.asan-dynamic-i386.vers || true
cat: ./obj/build/x86_64-unknown-linux-gnu/native/asan/build/lib/asan/clang_rt.asan-dynamic-i386.vers: No such file or directory
travis_fold:end:after_failure.5
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$ dmesg | grep -i kill

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)

nikomatsakis

Nice!

nikomatsakis · 2018-07-24T20:06:28Z

src/librustc/infer/anon_types/mod.rs

                            },
+                            Some(hir::map::NodeImplItem(item)) => match item.node {
+                                hir::ImplItemKind::Existential(_) => may_define_existential_type(


I guess one of the wacky -- but perhaps .. fine -- consequences of this is that one could do something like

impl Foo for Bar { existential type Item; fn method() { fn helper() -> <Bar as Foo>::Item { .. } }

and that helper fn might count as a defining use?

I feel like we should only allow other members of the impl to be a defining use.

Not allowing this kind of defining use would be inconsistent with how normal existential types work.

I don't see it as particularly inconsistent — depends on your POV, I suppose. It seems to me that the various "sugared forms" (e.g., impl Trait) don't desugar directly to an existential type "sibling item", because they have different sets of defining uses... in the case of a function, only the fn return type in question. In the case of an impl, we get to decide?

For that matter, I do wonder if we would rather have the syntax here be type Item = impl Foo.

(cc @cramertj on this particular question)

I'm ok landing either way, but I would want to open an unresolved question on this point

yea the syntax is horrible on purpose. It's the only one everyone could agree on that we do not want.

I added two unresolved questions to the tracking issue. Dear god I hope they won't get lost. =)

IMO it's fine for helper to be a defining use of Item because it's "in the scope" of Item's definition (in this case, the trait impl).

Was there another discussion on syntax? Two points:

sometimes there are no constraints: but type Item; is of course ambiguous

"existential" is not really the correct term (mathematically it means "there exists at least one such ..."); really we just mean "indirectly specified"

So possibly indirect type Item; or unspec type Item; ?

This implemented the placeholder syntax from the RFC. Please check out the discussion on the tracking issue and follow up RFCs. The syntax has been heavily discussed there and is currently being RFCed as type Item = impl Trait;. So if you disagree with the proposed syntax or otherwise have opinions on this topic, bring it up on that RFC.

nikomatsakis · 2018-07-24T20:21:23Z

src/librustc/traits/project.rs

+    }
+    let substs = translate_substs(selcx.infcx(), param_env, impl_def_id, substs, assoc_ty.node);
+    let ty = if let ty::AssociatedKind::Existential = assoc_ty.item.kind {
+        tcx.mk_anon(assoc_ty.item.def_id, substs)


huh, something looks fishy here -- you are using substs as part of ty in this case...

yea, I'm gonna add some generics tests and do this properly

src/librustc/traits/project.rs

    } else {
        tcx.type_of(assoc_ty.item.def_id)
    };
-    let substs = translate_substs(selcx.infcx(), param_env, impl_def_id, substs, assoc_ty.node);
    Progress {
        ty: ty.subst(tcx, substs),


nikomatsakis · 2018-07-24T20:22:25Z

src/librustc/traits/specialize/specialization_graph.rs

+                | (Type, Existential)
+                => tcx.hygienic_eq(impl_item.ident, trait_item_name, trait_def_id),
+
+                _ => false,


I'd prefer to see this spelled out:

e.g., (Const, _) | (Method, _) | (Type, _) etc

this way when new kinds are added, we won't overlook them

nikomatsakis · 2018-07-25T14:37:26Z

@bors r+

bors · 2018-07-25T14:37:27Z

📌 Commit 33712a8 has been approved by nikomatsakis

bors · 2018-07-27T00:43:47Z

⌛ Testing commit 33712a8 with merge f1ecabf25ee6d7fc4a607e2e820013b8bf8619a1...

bors · 2018-07-27T02:32:08Z

💔 Test failed - status-travis

rust-highfive · 2018-07-27T02:32:09Z

The job dist-powerpc64le-linux of your PR failed on Travis (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.

[01:46:26] [ 39%] Building MipsGenGlobalISel.inc...
[01:46:26] [ 39%] Building AArch64GenInstrInfo.inc...
[01:46:26] [ 39%] Building MipsGenInstrInfo.inc...

Broadcast message from root@travis-job-af0c6e06-6d69-43e8-bed8-f2f061e6472c
 (unknown) at 2:31 ...
The system is going down for power off NOW!
[01:46:27] 
[01:46:27] Session terminated, terminating shell...make[2]: make[2]: *** Deleting file `lib/Target/Mips/MipsGenGlobalISel.inc.tmp'
[01:46:27] *** Deleting file `lib/Target/X86/X86GenDAGISel.inc.tmp'
[01:46:27] make[2]: *** [lib/Target/Mips/MipsGenInstrInfo.inc.tmp] Terminatedmake[2]: *** [lib/Target/X86/X86GenDAGISel.inc.tmp] Terminated
[01:46:27] 
[01:46:27] make[1]: *** [lib/Target/X86/CMakeFiles/X86CommonTableGen.dir/all] Terminated
[01:46:27] make[1]: *** [lib/Target/Mips/CMakeFiles/MipsCommonTableGen.dir/all] Terminated
[01:46:27] make[2]: *** [lib/Target/AArch64/AArch64GenInstrInfo.inc.tmp] Terminated
[01:46:27] make[1]: *** [lib/Target/AArch64/CMakeFiles/AArch64CommonTableGen.dir/all] Terminated
[01:46:27]  ...terminated.
[01:46:27] make: *** [all] Terminated

The command "stamp sh -x -c "$RUN_SCRIPT"" exited with 143.
travis_time:start:1b968fa0
$ date && (curl -fs --head https://google.com | grep ^Date: | sed 's/Date: //g' || true)

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)

kennytm · 2018-07-27T03:41:13Z

@bors retry

bors · 2018-07-27T05:32:52Z

⌛ Testing commit 33712a8 with merge c82d35770ac9d4b53bb93247456206c003c5e4e8...

bors · 2018-07-27T06:08:12Z

💔 Test failed - status-travis

rust-highfive · 2018-07-27T06:08:14Z

The job dist-powerpc64le-linux of your PR failed on Travis (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.

#######################################################                   77.6%
######################################################################## 100.0%
[00:01:27] extracting /checkout/obj/build/cache/2018-07-13/rust-std-beta-x86_64-unknown-linux-gnu.tar.gz
[00:01:28] downloading https://static.rust-lang.org/dist/2018-07-13/rustc-beta-x86_64-unknown-linux-gnu.tar.gz
No output has been received in the last 30m0s, this potentially indicates a stalled build or something wrong with the build itself.
Check the details on how to adjust your build configuration on: https://docs.travis-ci.com/user/common-build-problems/#Build-times-out-because-no-output-was-received
The build has been terminated

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)

kennytm · 2018-07-27T06:24:09Z

@bors retry #40474

what is happening 😒

bors · 2018-07-27T07:16:20Z

⌛ Testing commit 33712a8 with merge 7c2aeb9...

@nikomatsakis

…tsakis Implement associated existential types r? @nikomatsakis no idea if these work with generic traits. I'm going home for the day 🤣

bors · 2018-07-27T09:10:03Z

☀️ Test successful - status-appveyor, status-travis
Approved by: nikomatsakis
Pushing 7c2aeb9 to master...

Implement associated existential types

9130efd

rust-highfive assigned nikomatsakis Jul 23, 2018

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Jul 23, 2018

nikomatsakis requested changes Jul 24, 2018

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oli-obk added 2 commits July 25, 2018 10:47

Fix associated existentials for generic traits

93974cb

Remove useless comment

01eacd8

oli-obk force-pushed the associated_existential_types branch from 65e016b to 01eacd8 Compare July 25, 2018 08:49

Add type system canaries for potential future bugs

33712a8

aturon mentioned this pull request Jul 25, 2018

Tracking issue for impl Trait (RFC 1522, RFC 1951, RFC 2071) #34511

Closed

29 tasks

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 Jul 25, 2018

nikomatsakis approved these changes Jul 25, 2018

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bors added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Jul 27, 2018

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 Jul 27, 2018

bors added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Jul 27, 2018

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 Jul 27, 2018

bors added a commit that referenced this pull request Jul 27, 2018

Auto merge of #52650 - oli-obk:associated_existential_types, r=nikoma…

7c2aeb9

…tsakis Implement associated existential types r? @nikomatsakis no idea if these work with generic traits. I'm going home for the day 🤣

bors merged commit 33712a8 into rust-lang:master Jul 27, 2018

eddyb mentioned this pull request Aug 29, 2018

Use the new explicit form of impl Trait to put all in a trait. rust-lang/gll#33

Open

pnkfelix mentioned this pull request Oct 9, 2018

error: internal compiler error: Accessing (*_310) with the kind Write(Move) shouldn't be possible #54597

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Centril mentioned this pull request Jul 28, 2019

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

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oli-obk deleted the associated_existential_types branch June 15, 2020 15:28

traviscross mentioned this pull request Apr 2, 2023

TAIT defining scope options #107645

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Implement associated existential types #52650

Implement associated existential types #52650

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Implement associated existential types #52650

Implement associated existential types #52650

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