Some more pattern cleanup and bugfixing #34365

petrochenkov · 2016-06-19T17:07:43Z

The next part of #34095

The most significant fixed mistake is definitions for partially resolved associated types not being updated after full resolution.

fn f<T: Fn()>(arg: T::Output) { .... } // <- the definition of T::Output was not updated in def_map

For this reason unstable associated types of stable traits, like FnOnce::Output, could be used in stable code when written in unqualified form. Now they are properly checked, this is a [breaking-change] (pretty minor one, but a crater run would be nice). The fix is not to use unstable library features in stable code, alternatively FnOnce::Output can be stabilized.

Besides that, paths in struct patterns and expressions S::A { .. } are now fully resolved as associated types. Such types cannot be identified as structs at the moment, i.e. the change doesn't make previously invalid code valid, but it improves error diagnostics.

Other changes: Def::Err is supported better (less chances for ICEs for erroneous code), some incorrect error messages are corrected, some duplicated error messages are not reported, ADT definitions are now available through constructor IDs, everything else is cleanup and code audit.

Fixes #34209
Closes #22933 (adds tests)

r? @eddyb

eddyb · 2016-06-19T17:15:33Z

cc @nrc @nikomatsakis

eddyb · 2016-06-19T17:39:36Z

src/librustc_typeck/collect.rs

+    let adt = ccx.tcx.intern_adt_def(did, ty::AdtKind::Struct, variants);
+    if let Some(ctor_id) = ctor_id {
+        // Make adt definition available through constructor id as well.
+        ccx.tcx.insert_adt_def(ctor_id, adt);


Why was this done?

So you can go directly from Def::Struct to ADT definition regardless of where this Def::Struct is used - in a pattern, expression or a type. Sometimes Def::Struct denotes a type and sometimes a constructor and previously lookup_adt_def worked only with Def::Structs in type context and panicked otherwise, so workarounds had to be used.

petrochenkov · 2016-06-21T17:37:02Z

src/librustc_typeck/check/mod.rs

+        let ty_substituted = self.instantiate_type_scheme(path.span, substs, &type_scheme.ty);
+        self.write_ty(node_id, ty_substituted);
+        self.write_substs(node_id, ty::ItemSubsts {
+            substs: substs


Hm, this is probably a mistake and regression. The substs written are substs before instantiate_type_scheme, not after.
I.e. for

type Alias<T> = S<T, u16>; // Inside match Alias::<u8> { .. }

only u8 is written, not [u8, u16].
However, instantiate_path does the same mistake(?) even without this PR.

The AST part of rust-lang#34365 plugin-[breaking-change] cc rust-lang#31645

bors · 2016-06-28T04:46:30Z

☔ The latest upstream changes (presumably #34424) made this pull request unmergeable. Please resolve the merge conflicts.

petrochenkov · 2016-06-29T00:30:12Z

Rebased.
Still waiting for crater run.

eddyb · 2016-06-29T12:11:34Z

@petrochenkov Sorry about that, @nikomatsakis is on vacation.
But I have crater access now, so here's the crater report.
The two actual root regressions are in traverse and parsell, both using FnOnce::Output.

nikomatsakis · 2016-06-29T15:41:18Z

So as I wrote on IRC, I don't think that F::Output (where F: FnOnce) has to be unstable -- and I'm not sure it was intended to be, though I'll have to check around. What we wanted to be careful about was something like F: FnOnce<()>, because this reveals the form of the "input types", and there was some concern that F: FnOnce<(A,B)> might change to F: FnOnce<A,B> or something, depending on what approach we wound up with for variadic generics. But I think we know that the return type will always be an associated type, and I see no reason we would ever change its name.

bors · 2016-06-30T04:44:34Z

☔ The latest upstream changes (presumably #34552) made this pull request unmergeable. Please resolve the merge conflicts.

aturon · 2016-06-30T21:30:15Z

But I think we know that the return type will always be an associated type, and I see no reason we would ever change its name.

I agree on both counts. It seems OK for this name to be available on stable Rust.

aturon · 2016-07-07T21:19:18Z

Lang team meeting: we decided we should try this PR, but with marking the Output type as stable, and see whether that eliminates the regressions.

eddyb · 2016-07-07T21:24:10Z

@petrochenkov Looks like FnOnce::Output is explicitly marked unstable so just flipping that should work. This is likely what @nikomatsakis had in mind.

Instead of Def::Err erroneous bindings can get usual definitions that doesn't require special cases later on and have less chances to generate ICE.

…k_pat_path Update definitions in def_map for associated types written in unqualified form (like `Self::Output`) Cleanup finish_resolving_def_to_ty/resolve_ty_and_def_ufcs Make VariantDef's available through constructor IDs

Treat Def::Err correctly in struct patterns Make instantiate_path and instantiate_type a bit closer to each other

petrochenkov · 2016-07-08T10:56:09Z

Rebased, FnOnce::Output is stabilized.

eddyb · 2016-07-09T16:07:05Z

Crater report only shows 4 regressions in code using the unstable librustc APIs.

@alexcrichton @aturon Can we merge this with the stabilization of FnOnce::Output directly?

aturon · 2016-07-09T19:36:18Z

@eddyb Yep, at this point everybody's signed off on that step.

eddyb · 2016-07-09T19:42:11Z

@bors r+

bors · 2016-07-09T19:42:12Z

📌 Commit d27e55c has been approved by eddyb

bors · 2016-07-09T22:16:21Z

⌛ Testing commit d27e55c with merge f93aaf8...

@eddyb

Some more pattern cleanup and bugfixing The next part of #34095 The most significant fixed mistake is definitions for partially resolved associated types not being updated after full resolution. ``` fn f<T: Fn()>(arg: T::Output) { .... } // <- the definition of T::Output was not updated in def_map ``` For this reason unstable associated types of stable traits, like `FnOnce::Output`, could be used in stable code when written in unqualified form. Now they are properly checked, this is a **[breaking-change]** (pretty minor one, but a crater run would be nice). The fix is not to use unstable library features in stable code, alternatively `FnOnce::Output` can be stabilized. Besides that, paths in struct patterns and expressions `S::A { .. }` are now fully resolved as associated types. Such types cannot be identified as structs at the moment, i.e. the change doesn't make previously invalid code valid, but it improves error diagnostics. Other changes: `Def::Err` is supported better (less chances for ICEs for erroneous code), some incorrect error messages are corrected, some duplicated error messages are not reported, ADT definitions are now available through constructor IDs, everything else is cleanup and code audit. Fixes #34209 Closes #22933 (adds tests) r? @eddyb

bors · 2016-07-10T01:16:46Z

rust-highfive assigned eddyb Jun 19, 2016

petrochenkov force-pushed the deferr branch from 0dcd412 to 914bf7d Compare June 19, 2016 17:08

eddyb added the S-waiting-on-crater Status: Waiting on a crater run to be completed. label Jun 19, 2016

eddyb reviewed Jun 19, 2016
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petrochenkov mentioned this pull request Jun 19, 2016

Merge PatKind::QPath into PatKind::Path in AST #34368

Merged

petrochenkov reviewed Jun 21, 2016
View reviewed changes

petrochenkov mentioned this pull request Jun 22, 2016

Rustc panic when wrong namespace in destructuring patern #34413

Closed

jseyfried added a commit to jseyfried/rust that referenced this pull request Jun 25, 2016

Rollup merge of rust-lang#34368 - petrochenkov:astqpath, r=Manishearth

4e2e31c

The AST part of rust-lang#34365 plugin-[breaking-change] cc rust-lang#31645

petrochenkov force-pushed the deferr branch from 914bf7d to 6bd1d7a Compare June 29, 2016 00:29

eddyb added I-nominated T-lang Relevant to the language team, which will review and decide on the PR/issue. and removed S-waiting-on-crater Status: Waiting on a crater run to be completed. labels Jun 29, 2016

petrochenkov mentioned this pull request Jun 29, 2016

Non-existent struct enum variant in pattern causes ICE #34564

Closed

pnkfelix removed the I-nominated label Jul 7, 2016

petrochenkov added 6 commits July 8, 2016 12:36

Don't generate Def::Err if it's not stored in def_map immediately

d3c94b2

Cleanup of some pattern related code

ba419a7

Better support for associated types in struct patterns

4d4c7be

Do not generate Def::Err in bindings

eb32440

Instead of Def::Err erroneous bindings can get usual definitions that doesn't require special cases later on and have less chances to generate ICE.

Remove unnecessary accessor function VariantDefData::kind

49ea3d4

petrochenkov added 5 commits July 8, 2016 12:42

Resolve partially resolved paths in struct patterns/expressions

a397b60

Treat Def::Err correctly in struct patterns Make instantiate_path and instantiate_type a bit closer to each other

Merge PatKind::QPath into PatKind::Path in HIR

9c05fb2

Add tests + Fix rustdoc regression + Fix rebase

2859f8b

Move some common code into check_struct_path

390b639

Stabilize FnOnce::Output + Fix rebase

d27e55c

petrochenkov force-pushed the deferr branch from 6bd1d7a to d27e55c Compare July 8, 2016 10:53

bors merged commit d27e55c into rust-lang:master Jul 10, 2016

This was referenced Jul 10, 2016

rustfmt librustc_resolve #34584

Closed

Simplify the macro hygiene algorithm #34570

Merged

extended information for slice pattern errors (E0527 through E0529) #34319

Merged

petrochenkov mentioned this pull request Jul 12, 2016

Tracking issue for Fn traits (unboxed_closures & fn_traits feature) #29625

Open

2 tasks

petrochenkov deleted the deferr branch September 21, 2016 20:04

petrochenkov restored the deferr branch September 21, 2016 20:04

petrochenkov deleted the deferr branch September 21, 2016 20:04

TimNN mentioned this pull request Oct 7, 2016

“Let NullaryConstructor = something;” causes internal compiler error: “tried to overwrite interned AdtDef” #37026

Closed

petrochenkov mentioned this pull request Oct 24, 2016

Support Self in struct expressions and patterns #37035

Merged

compiler-errors mentioned this pull request Jul 2, 2024

Async closures rust-lang/rfcs#3668

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Some more pattern cleanup and bugfixing #34365

Some more pattern cleanup and bugfixing #34365

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Some more pattern cleanup and bugfixing #34365

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