tree eda3f02564959285bd58981b80e6ed87b746c9f4
parent 4ba1aaf35f1ad55ddd094ab751f62dcf227a3185
parent 14eb94fe7a3ca3a92d5d7e42744d105c0fc6d527
author bors <bors@rust-lang.org> 1611024898 +0000
committer bors <bors@rust-lang.org> 1611024898 +0000

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`