…ies with more than one element.

* If there are generics, don't allow to have quotes.

* Move all functions outside parseQuery

 * Forbid generics without a path (so "<p>" is forbidden).
 * Change `handleSingleArg` so that it takes `results_others`, `results_in_args` and `results_returned` as arguments instead of using the "global" variables.
 * Change `createQueryElement` so that it returns the newly created element instead of taking `elems` as argument.
 * Improve documentation

…e handled correctly

…tabs

…eBNF does not allow elements without a name

…elements

This breaks on submodules (see rust-lang#96188). Disable the assertion for now until I can think of a proper
fix.

This doesn't revert any of the changes in `Step`s themselves, only what
`ShouldRun::paths` does.

This implementation returns a best attempt at the current exe path. On
fuchsia, fdio will always use `argv[0]` as the process name and if it is
not set then an error will be returned. Because this is not guaranteed
to be the case, this implementation returns an error if `argv` does not
contain any elements.

Previously, we would retrieve the span from the `Body` using
the `locations` field. However, we may end up changing the
`locations` field when moving a constraint from a promoted
to a different body.

We now store the original `Span` in a dedication field, so that
changes to the `locations` do not affect the quality of our
diagnostics.

…ch, r=notriddle

Create real parser for search queries

You can test it [here](https://rustdoc.crud.net/imperio/improve-rustdoc-search/std/index.html).

This PR adds a real parser for the query engine in rustdoc. The parser is quite simple but it allows to makes query handling much easier. I added a new testsuite to ensure it works as expected and ran fuzzing checks on it for a few hours without problems.

So about the parser: as you can see in the screenshot, it handles recursive generics parsing. It also allows to set which item should use exact matching by adding double-quotes around it (look for `exact_search` in the screenshot).

Now about the query engine itself: I simplified it a lot thanks to the parsed query. It behaves mostly the same when there is only one argument, but is much more powerful when there are more than one.

When making this change, we also removed the support for multi-query.

PS: A big part of the PR is tests and test-related code. :)

r? `@camelid`

…andry

[fuchsia] Add implementation for `current_exe`

This implementation returns a best attempt at the current exe path. On
fuchsia, fdio will always use `argv[0]` as the process name and if it is
not set then an error will be returned. Because this is not guaranteed
to be the case, this implementation returns an error if `argv` does not
contain any elements.

Remove assertion that all paths in `ShouldRun` exist

This breaks on submodules (see rust-lang#96188). Disable the assertion for now until I can think of a proper
fix.

This doesn't revert any of the changes in `Step`s themselves, only what
`ShouldRun::paths` does.

Fix locations for intrinsics impls and change to links

These still referred to `rustc_mir`.

Add an explicit `Span` field to `OutlivesConstraint`

Previously, we would retrieve the span from the `Body` using
the `locations` field. However, we may end up changing the
`locations` field when moving a constraint from a promoted
to a different body.

We now store the original `Span` in a dedication field, so that
changes to the `locations` do not affect the quality of our
diagnostics.