Handle `#[cfg]`s on generic parameters
Records attributes on generic parameters in the item tree and filters out generic parameters disabled by `#[cfg]`s in `generic_params_query`.
Closes#11756
internal: Turn unresolved proc macro expansions into missing expressions
Reduces the amount of type related errors one gets when proc macro expansion is disabled.
SCIP requires symbols to be unique, but multiple functions may have a
parameter with the same name. Qualify parameters according to the
containing function.
When cross compiling macos → dragonfly the dist build fails in the
proc-maro-test-impl crate with the following error:
ld: unknown option: -z\nclang: error: linker command failed with
exit code 1 (use -v to see invocation)
This appears to be a wart stemming from using an Apple host for cross
compiling. Passing the target along to cargo allows it to pick up
a linker that it understands and DTRT.
Exclude non-identifier aliases from completion filtering text
When building `CompletionItem`s, this excludes aliases that aren't valid identifiers from the "lookup" text used to filter completions in the LSP client. Including them results in weird completion filtering behavior e.g. `Partial>` matching a completion for the `PartialOrd` trait because it has a doc alias of ">".
Closes#14692
Add ExternCrateDecl to HIR
Adding these doesn't really require much design effort as they represent a single import, unlike use trees which are one item that represent 0 or more imports.
We only resolve to this definition when actually resolving on the name or alias of an `extern crate name as alias` item, not usages yet as that requires far more changes that won't lead anywhere without giving it more thought. Nevertheless the changes slightly improve IDE things, an example being hover on the decl showing the merged doc comments for example.
cc https://github.com/rust-lang/rust-analyzer/issues/14079
Added remove unused imports assist
This resolves the most important part of #5131. I needed to make a couple of cosmetic changes to the search infrastructure to do this.
A few open questions:
* Should imports that don't resolve to anything be considered unused? I figured probably not, but it would be a trivial change to make if we want it.
* Is there a cleaner way to make the edits to the use list?
* Is there a cleaner way to get the list of uses that intersect the current selection?
* Is the performance acceptable? When testing this on itself, it takes a good couple seconds to perform the assist.
* Is there a way to hide the rustc diagnostics that overlap with this functionality?
