rust/compiler/rustc_typeck
bors 94e6ea9fc9 Auto merge of #81103 - zackmdavis:comma_trail, r=davidtwco
don't suggest erroneous trailing comma after `..`

In #76612, suggestions were added for missing fields in patterns. However, the suggestions are being inserted just at the end
of the last field in the pattern—before any trailing comma after the last field. This resulted in the "if you don't care about missing fields" suggestion to recommend code with a trailing comma after the field ellipsis (`..,`), which is actually not legal ("`..` must be at the end and cannot have a trailing comma")!

Incidentally, the doc-comment on `error_unmentioned_fields` was using `you_cant_use_this_field` as an example field name (presumably copy-paste inherited from the description of Issue #76077), but the present author found this confusing, because unmentioned fields aren't necessarily unusable.

The suggested code in the diff this commit introduces to `destructuring-assignment/struct_destructure_fail.stderr` doesn't work, but it didn't work beforehand, either (because of the "found reserved identifier `_`" thing), so you can't really call it a regression; it could be fixed in a separate PR.

Resolves #78511.

r? `@davidtwco` or `@estebank`
2021-01-19 02:54:58 +00:00
..
src Auto merge of #81103 - zackmdavis:comma_trail, r=davidtwco 2021-01-19 02:54:58 +00:00
Cargo.toml
README.md

For high-level intro to how type checking works in rustc, see the type checking chapter of the rustc dev guide.