Rename `bool::then_*` to `bool::to_option_*` and use where appropriate
Name change following https://github.com/rust-lang/rfcs/pull/2757. Also try it out throughout the compiler in places I think makes the code more readable.
The construction of the GlobalCtxt is moved from a generator's stack to
the Queries struct. Since the GlobalCtxt requires the HIR Forest and the
arenas to live longer, those are moved into Queries the same way.
The resulting handling of objects is more brittle, because consumers of
the Once objects need to be careful of their initialisation.
Move to using Box<dyn Fn() -> ...> so that we can let plugins register
state.
This also adds a callback that'll get called from plugin registration so
that Clippy and other tools can register lints without using the plugin
API. The plugin API still works, but this new API is more compatible
with drivers other than rustc.
`Compiler::compile()` is different to all the other `Compiler` methods
because it lacks a `Queries` entry. It only has one call site, which is
in a test that doesn't need its specific characteristics.
This patch replaces that call with a call to `Compile::link()`, which is
similar enough for the test's purposes. It also notes that the method is
an illustrative example of how `Compiler` can be used.
`Compiler::register_plugins()` calls `passes::register_plugins()`, which
calls `Compiler::dep_graph_future()`. This is the only way in which a
`passes` function calls a `Compiler` function.
This commit moves the `dep_graph_future()` call out of
`passes::register_plugins()` and into `Compiler::register_plugins()`,
which is a more sensible spot for it. This will delay the loading of the
dep graph slightly -- from the middle of plugin registration to the end
of plugin registration -- but plugin registration is fast enough
(especially compared to expansion) that the impact should be neglible.
