Immovable generators
This adds support for immovable generators which allow you to borrow local values inside generator across suspension points. These are declared using a `static` keyword:
```rust
let mut generator = static || {
let local = &Vec::new();
yield;
local.push(0i8);
};
generator.resume();
// ERROR moving the generator after it has resumed would invalidate the interior reference
// drop(generator);
```
Region inference is no longer affected by the types stored in generators so the regions inside should be similar to other code (and unaffected by the presence of `yield` expressions). The borrow checker is extended to pick up the slack so interior references still result in errors for movable generators. This fixes#44197, #45259 and #45093.
This PR depends on [PR #44917 (immovable types)](https://github.com/rust-lang/rust/pull/44917), I suggest potential reviewers ignore the first commit as it adds immovable types.
rustdoc: Populate external_traits with traits only seen in impls
This means default methods can always be found and "Important traits" will include all spotlight traits.
No longer parse it.
Remove AutoTrait variant from AST and HIR.
Remove backwards compatibility lint.
Remove coherence checks, they make no sense for the new syntax.
Remove from rustdoc.
The Generics now contain one Vec of an enum for the generic parameters,
rather than two separate Vec's for lifetime and type parameters.
Additionally, places that previously used Vec<LifetimeDef> now use
Vec<GenericParam> instead.
nll part 5
Next round of changes from the nll-master branch.
Extensions:
- we now propagate ty-region-outlives constraints out of closures and into their creator when necessary
- we fix a few ICEs that can occur by doing liveness analysis (and the resulting normalization) during type-checking
- we handle the implicit region bound that assumes that each type `T` outlives the fn body
- we handle normalization of inputs/outputs in fn signatures
Not included in this PR (will come next):
- handling `impl Trait`
- tracking causal information
- extended errors
r? @arielb1
