…truct constructor

Only display the "remove this comma" suggestion when followed by an identifier

…bout why the move wasn't a copy.

This should address rust-lang#51190.

…ing.rs robust for NLL.

We currently give a specific message when encountering a `..` anywhere
other than the end of a pattern. Modify the parser to accept it (while
still emitting the error) so that we don't also trigger "missing fields
in pattern" errors afterwards.

When using `..` somewhere other than the end, parse the rest of the
pattern correctly while still emitting an error.

Add suggestions to either remove trailing `,` or moving the `..` to the
end.

fdio_spawn_etc is the preferred way of creating processes on Fuchsia
now.

Issue rust-lang#50974 : Suboptimal error in case of duplicate `,` in struct constructor

Fixes rust-lang#50974

Accept `..` in incorrect position to avoid further errors

We currently give a specific message when encountering a `..` anywhere
other than the end of a pattern. Modify the parser to accept it (while
still emitting the error) so that we don't also trigger "missing fields
in pattern" errors afterwards.

Add suggestions to either remove trailing `,` or moving the `..` to the
end.

Follow up to rust-lang#49268.

…ved-from-behind-borrow, r=nikomatsakis

NLL: report type moved from behind borrow of array/slice

When NLL has illegal move due to borrowed content in an array or slice, provide feedback about why the move wasn't a copy.

Drive by: While comparing the resulting `.nll.stderr` files to their old borrowck variants, I noticed that the test for borrowck-vec-pattern-nesting.rs was not signaling some errors under NLL due to the test assuming lexical lifetimes. So I fixed that too.

Fix rust-lang#51190

Refactor the const eval diagnostic API

* no longer report "const eval error" for things that have typeck errors
* errors and lints have saner spans and messages
* unified the diagnostic logic (const eval errors were slightly different depending on where they were reported, and there was also code duplication between the different reporters)
* report errors if an erroneous constant is used inside a promoted (fixes most of rust-lang#50814)

[fuchsia] Migrate from launchpad to fdio_spawn_etc

fdio_spawn_etc is the preferred way of creating processes on Fuchsia
now.

cc @abarth