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Trait predicate ambiguities are not always in Self - #78111
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rust-highfive
commented
Oct 19, 2020
r? @lcnr (rust_highfive has picked a reviewer for you, use r? to override) |
lcnr
commented
Oct 19, 2020
bors
commented
Oct 19, 2020
📌 Commit 4cf890cacd538c608e8ac6dcfc7b22a7d5043344 has been approved by |
lcnr
commented
Oct 19, 2020
@bors r- missed something in my review |
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4cf890c to
c146e8cComparelcnr
commented
Oct 19, 2020
@bors r+ rollup |
bors
commented
Oct 19, 2020
📌 Commit c146e8c has been approved by |
Searching "type annotations needed" shows a whole bunch of other open issue reports that should be fixed by this (and I can confirm a few locally), non-exhaustive list: #75398, #72616, #71732 I'm not sure if/how many of these are worth adding extra tests for or just marking as closed by this. |
lcnr
commented
Oct 19, 2020
SNCPlay42
commented
Oct 19, 2020
Should we r- and add tests to this PR or clean these up later? |
Rollup of 10 pull requests Successful merges: - rust-lang#77612 (BTreeMap: test invariants more thoroughly and more readably) - rust-lang#77761 (Assert that pthread mutex initialization succeeded) - rust-lang#77778 ([x.py setup] Allow setting up git hooks from other worktrees) - rust-lang#77838 (const keyword: brief paragraph on 'const fn') - rust-lang#77923 ([net] apply clippy lints) - rust-lang#77931 (Fix false positive for `unused_parens` lint) - rust-lang#77959 (Tweak ui-tests structure) - rust-lang#78105 (change name in .mailmap) - rust-lang#78111 (Trait predicate ambiguities are not always in `Self`) - rust-lang#78121 (Do not ICE on pattern that uses a binding multiple times in generator) Failed merges: r? `@ghost`
lcnr
commented
Oct 20, 2020
will mark these issues as |
When reporting ambiguities in trait predicates, the compiler incorrectly assumed the ambiguity was always in the type the trait should be implemented on, and never the generic parameters of the trait. This caused silly suggestions for predicates like
<KnownType as Trait<_>>, such as giving explicit types to completely unrelated variables that happened to be of typeKnownType.This also reverts #73027, which worked around this issue in some cases and does not appear to be necessary any more.
fixes#77982
fixes#78055