diff options
| author | Mara Bos <m-ou.se@m-ou.se> | 2020-11-16 17:26:38 +0100 |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2020-11-16 17:26:38 +0100 |
| commit | e6b6c8e4fc63b2229e4db079510c1dac26917437 (patch) | |
| tree | 4f3c7a87cf0dadf0ddc4485c9d823ac351058844 | |
| parent | c3da682249d2d6fc80735e8b0da8be4b2451f551 (diff) | |
| parent | 0bc04e327c54db788b0a7093879e3c4e51301356 (diff) | |
| download | rust-e6b6c8e4fc63b2229e4db079510c1dac26917437.tar.gz rust-e6b6c8e4fc63b2229e4db079510c1dac26917437.zip | |
Rollup merge of #79087 - ThePuzzlemaker:issue-79083-docfix, r=RalfJung
Update E0744 about control flow in `const` contexts to accurately describe when the error is triggered and why This PR fixes #79083. `const fn` currently supports `if`, `match`, `loop`, and `while` in terms of control flow. The error relating to control flow in `const` contexts currently states that those control flow constructs are not allowed in `const` contexts. That is no longer true, as RFC 2342 and 2344 were [stabilized](https://github.com/rust-lang/rust/pull/72437). `for` loops, however, as well as `?` and `.await` are still not allowed, so I changed the error message to be more descriptive of the error as it is not just control flow that could trigger this error. I also added links to tracking issues that mark things that are blocking the usage of these expressions.
| -rw-r--r-- | compiler/rustc_error_codes/src/error_codes/E0744.md | 19 |
1 files changed, 11 insertions, 8 deletions
diff --git a/compiler/rustc_error_codes/src/error_codes/E0744.md b/compiler/rustc_error_codes/src/error_codes/E0744.md index 14cff3613e0..45804ab266e 100644 --- a/compiler/rustc_error_codes/src/error_codes/E0744.md +++ b/compiler/rustc_error_codes/src/error_codes/E0744.md @@ -1,4 +1,4 @@ -A control-flow expression was used inside a const context. +An unsupported expression was used inside a const context. Erroneous code example: @@ -12,12 +12,15 @@ const _: i32 = { }; ``` -At the moment, `if` and `match`, as well as the looping constructs `for`, -`while`, and `loop`, are forbidden inside a `const`, `static`, or `const fn`. +At the moment, `for` loops, `.await`, and the `Try` operator (`?`) are forbidden +inside a `const`, `static`, or `const fn`. -This will be allowed at some point in the future, but the implementation is not -yet complete. See the tracking issue for [conditionals] or [loops] in a const -context for the current status. +This may be allowed at some point in the future, but the implementation is not +yet complete. See the tracking issues for [`async`] and [`?`] in `const fn`, and +(to support `for` loops in `const fn`) the tracking issues for [`impl const +Trait for Ty`] and [`&mut T`] in `const fn`. -[conditionals]: https://github.com/rust-lang/rust/issues/49146 -[loops]: https://github.com/rust-lang/rust/issues/52000 +[`async`]: https://github.com/rust-lang/rust/issues/69431 +[`?`]: https://github.com/rust-lang/rust/issues/74935 +[`impl const Trait for Ty`]: https://github.com/rust-lang/rust/issues/67792 +[`&mut T`]: https://github.com/rust-lang/rust/issues/57349 |