`CompilerError` has `CompilationFailed` and `ICE` variants, which seems
reasonable at first. But the way it identifies them is flawed:
- If compilation errors out, i.e. `RunCompiler::run` returns an `Err`,
it uses `CompilationFailed`, which is reasonable.
- If compilation panics with `FatalError`, it catches the panic and uses
`ICE`. This is sometimes right, because ICEs do cause `FatalError`
panics, but sometimes wrong, because certain compiler errors also
cause `FatalError` panics. (The compiler/rustdoc/clippy/whatever just
catches the `FatalError` with `catch_with_exit_code` in `main`.)
In other words, certain non-ICE compilation failures get miscategorized
as ICEs. It's not possible to reliably distinguish the two cases, so
this commit merges them. It also renames the combined variant as just
`Failed`, to better match the existing `Interrupted` and `Skipped`
variants.
Here is an example of a non-ICE failure that causes a `FatalError`
panic, from `tests/ui/recursion_limit/issue-105700.rs`:
```
#![recursion_limit="4"]
#![invalid_attribute]
#![invalid_attribute]
#![invalid_attribute]
#![invalid_attribute]
#![invalid_attribute]
//~^ERROR recursion limit reached while expanding
fn main() {{}}
```
I added `tcx` argument to `internal` to force 'tcx to be the same
lifetime as TyCtxt. The only other solution I could think is to change
this function to be `unsafe`.
Simplify the `run` macro to avoid sometimes unnecessary dependency
on `TyCtxt`. Instead, users can use the new internal method `tcx()`.
Additionally, extend the macro to accept closures that may capture
variables.
These are non-backward compatible changes, but they only affect
internal APIs which are provided today as helper functions until we
have a stable API to start the compiler.
