In some limited cases, suggest where bounds for non-type params#82194
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bors merged 1 commit intorust-lang:masterfrom Feb 18, 2021
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In some limited cases, suggest where bounds for non-type params#82194bors merged 1 commit intorust-lang:masterfrom
where bounds for non-type params#82194bors merged 1 commit intorust-lang:masterfrom
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@bors r+ |
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📌 Commit 4e0a948ced62713a113636367b64b4aa76e05b4e has been approved by |
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@bors r- |
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@bors r=petrochenkov |
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📌 Commit 32c97da has been approved by |
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| help: consider introducing a `where` bound, but there might be an alternative better way to express this requirement | ||
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| LL | fn issue_81421<T: Read + Write>(mut stream: T) where &T: std::io::Read { |
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Is this syntax even allowed? where &T: .. will not compile due to missing lifetime parameters unfortunately
error[E0637]: `&` without an explicit lifetime name cannot be used here
--> src/lib.rs:2:23
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2 | fn foo<T>(x: T) where &T: std::io::Read { }
| ^ explicit lifetime name needed here
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We (I?) allow for limited "mistakes" in the suggested code as long as the compiler gives you further suggestions that lead you to working code. We can gate this suggestion in particular or/and extend E0637 to suggest where a lifetime can be added (we already have suggestions to extend foo's type param list and to add a for lifetime in other places).
Indeed writing where for<'a> &'a T: Read compiles successfully.
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Filed #82312 to track that potential work.
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…n, r=petrochenkov In some limited cases, suggest `where` bounds for non-type params Partially address rust-lang#81971.
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Rollup of 10 pull requests Successful merges: - rust-lang#81546 ([libtest] Run the test synchronously when hitting thread limit) - rust-lang#82066 (Ensure valid TraitRefs are created for GATs) - rust-lang#82112 (const_generics: Dont evaluate array length const when handling yet another error ) - rust-lang#82194 (In some limited cases, suggest `where` bounds for non-type params) - rust-lang#82215 (Replace if-let and while-let with `if let` and `while let`) - rust-lang#82218 (Make sure pdbs are copied along with exe and dlls when bootstrapping) - rust-lang#82236 (avoid converting types into themselves (clippy::useless_conversion)) - rust-lang#82246 (Add long explanation for E0549) - rust-lang#82248 (Optimize counting digits in line numbers during error reporting) - rust-lang#82256 (Print -Ztime-passes (and misc stats/logs) on stderr, not stdout.) Failed merges: r? `@ghost` `@rustbot` modify labels: rollup
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Partially address #81971.