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Pretty-print always-const trait predicates correctly #119476

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merged 1 commit into from
Jan 3, 2024

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@fmease fmease commented Dec 31, 2023

Follow-up to #119099.

r? fee1-dead

@rustbot 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 Dec 31, 2023
@fmease fmease added F-const_trait_impl `#![feature(const_trait_impl)]` F-effects `#![feature(effects)]` labels Dec 31, 2023
--> $DIR/call-generic-method-nonconst.rs:23:34
|
LL | pub const EQ: bool = equals_self(&S);
| ----------- ^^ the trait `~const Foo` is not implemented for `S`
| ----------- ^^ the trait `const Foo` is not implemented for `S`
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@fmease fmease Dec 31, 2023

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This regression is a bit unfortunate. Of course, from the perspective of the lowered code, it makes perfect sense that we register always-const trait predicate obligations in const item bodies, so technically speaking it's correct.

Still, it's bad that we're now basically saying S: const Trait is unsatisfied // required by bound ~const Trait in equals_self.

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r=me unless you want a specific review

@@ -20,7 +20,8 @@ const fn equals_self<T: ~const Foo>(t: &T) -> bool {
// Calling `equals_self` with something that has a non-const impl should throw an error, despite
// it not using the impl.

// FIXME(effects): We should print `S: ~const Foo` here instead.
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Why? I believe that S: const Foo makes sense here, since this is in an always-const context...

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@fmease fmease Jan 1, 2024

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It does make sense to me as I've written above, I'm just not super keen on the
diagnostic note required by this bound, *points at ~const*.
I can imagine ppl will open gh issues for that. Anyways.

Comment on lines +7 to +8
= note: expected constant `false`
found constant `true`
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We may want to intercept the TypeError here and special-case it for host params (as a follow-up)...

@fmease fmease force-pushed the pp-always-const-trait-preds branch from 19e4eb2 to 01ac44a Compare January 1, 2024 13:03
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fmease commented Jan 1, 2024

I've removed that FIXME.

@bors r=compiler-errors rollup

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bors commented Jan 1, 2024

📌 Commit 01ac44a has been approved by compiler-errors

It is now in the queue for this repository.

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bors commented Jan 1, 2024

🌲 The tree is currently closed for pull requests below priority 100. This pull request will be tested once the tree is reopened.

@bors 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 1, 2024
fmease added a commit to fmease/rust that referenced this pull request Jan 2, 2024
…, r=compiler-errors

Pretty-print always-const trait predicates correctly

Follow-up to rust-lang#119099.

r? fee1-dead
fmease added a commit to fmease/rust that referenced this pull request Jan 3, 2024
…, r=compiler-errors

Pretty-print always-const trait predicates correctly

Follow-up to rust-lang#119099.

r? fee1-dead
bors added a commit to rust-lang-ci/rust that referenced this pull request Jan 3, 2024
Rollup of 21 pull requests

Successful merges:

 - rust-lang#119086 (Query panic!() to useful diagnostic)
 - rust-lang#119239 (Remove unnecessary arm in `check_expr_yield`)
 - rust-lang#119298 (suppress change-tracker warnings in CI containers)
 - rust-lang#119319 (Document that File does not buffer reads/writes)
 - rust-lang#119434 (rc: Take *const T in is_dangling)
 - rust-lang#119444 (Rename `TyCtxt::is_closure` to `TyCtxt::is_closure_or_coroutine`)
 - rust-lang#119474 (Update tracking issue of naked_functions)
 - rust-lang#119476 (Pretty-print always-const trait predicates correctly)
 - rust-lang#119477 (rustdoc ui: adjust tooltip z-index to be above sidebar)
 - rust-lang#119479 (Remove two unused feature gates from rustc_query_impl)
 - rust-lang#119487 (Minor improvements in comment on `freshen.rs`)
 - rust-lang#119492 (Update books)
 - rust-lang#119494 (Deny defaults for higher-ranked generic parameters)
 - rust-lang#119498 (Update deadlinks of `strict_provenance` lints)
 - rust-lang#119505 (Don't synthesize host effect params for trait associated functions marked const)
 - rust-lang#119510 (Report I/O errors from rmeta encoding with emit_fatal)
 - rust-lang#119512 (Mark myself as back from leave)
 - rust-lang#119514 (coverage: Avoid a query stability hazard in `function_coverage_map`)
 - rust-lang#119523 (llvm: Allow `noundef` in codegen tests)
 - rust-lang#119534 (Update `thread_local` examples to use `local_key_cell_methods`)
 - rust-lang#119544 (Fix: Properly set vendor in i686-win7-windows-msvc target)

r? `@ghost`
`@rustbot` modify labels: rollup
@bors bors merged commit b41b169 into rust-lang:master Jan 3, 2024
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@rustbot rustbot added this to the 1.77.0 milestone Jan 3, 2024
rust-timer added a commit to rust-lang-ci/rust that referenced this pull request Jan 3, 2024
Rollup merge of rust-lang#119476 - fmease:pp-always-const-trait-preds, r=compiler-errors

Pretty-print always-const trait predicates correctly

Follow-up to rust-lang#119099.

r? fee1-dead
@fmease fmease deleted the pp-always-const-trait-preds branch January 3, 2024 20:57
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6 participants