Silence `TooGeneric` error
This error may be produced during intermediate failed attempts at evaluation of a generic const, which may nevertheless succeed later.
Fixes https://github.com/rust-lang/rust/issues/66962.
r? @eddyb
Fix ICE involving calling `Instance.ty` during const evaluation
Fixes#67639
`Instance.ty` assumes that we are in a fully monomorphic context (e.g.
codegen), and can therefore use an empty `ParamEnv` when performing
normalization. Howver, the MIR constant evaluator code ends up calling
`Instance.ty` as a result of us attemptign to 'speculatively'
const-evaluate generic functions during const propagation.
As a result,
we may end up with projections involving type parameters
(e.g. <T as MyTrait>::Bar>) in the type we are trying to normalize.
Normalization expects us to have proper predicates in the `ParamEnv` for
such projections, and will ICE if we don't.
This commit adds a new method `Instance.ty_env`, which takes a
`ParamEnv` for use during normalization. The MIR const-evaluator code is
changed to use this method, passing in the proper `ParamEnv` for the
context at hand.
Fixes#67639
`Instance.ty` assumes that we are in a fully monomorphic context (e.g.
codegen), and can therefore use an empty `ParamEnv` when performing
normalization. Howver, the MIR constant evaluator code ends up calling
`Instance.ty` as a result of us attemptign to 'speculatively'
const-evaluate generic functions during const propagation.
As a result,
we may end up with projections involving type parameters
(e.g. <T as MyTrait>::Bar>) in the type we are trying to normalize.
Normalization expects us to have proper predicates in the `ParamEnv` for
such projections, and will ICE if we don't.
This commit adds a new method `Instance.ty_env`, which takes a
`ParamEnv` for use during normalization. The MIR const-evaluator code is
changed to use this method, passing in the proper `ParamEnv` for the
context at hand.
Use self profile infrastructure for -Z time and -Z time-passes
There's no longer indentation for -Z time and -Z time-passes and duplicate timers between self profiling and -Z time-passes have been removed.
r? @wesleywiser
perf: Don't recurse into types that do not need normalizing
A bit speculative at this stage but profiling shows that type folding
takes up a substantial amount of time during normalization which may
indicate that many types may be folded despite there being nothing to
normalize
Nix reexports from `rustc_span` in `syntax`
Remove reexports `syntax::{source_map, symbol, edition}` and use `rustc_span` paths directly.
r? @petrochenkov
Suggest adding a lifetime constraint for opaque type
Fixes#67577, where code like this:
```
struct List {
data: Vec<String>,
}
impl List {
fn started_with<'a>(&'a self, prefix: &'a str) -> impl Iterator<Item=&'a str> {
self.data.iter().filter(|s| s.starts_with(prefix)).map(|s| s.as_ref())
}
}
```
will show this error:
```
Compiling playground v0.0.1 (/playground)
error[E0597]: `prefix` does not live long enough
--> src/lib.rs:6:47
|
5 | fn started_with<'a>(&'a self, prefix: &'a str) -> impl Iterator<Item=&'a str> {
| -- lifetime `'a` defined here --------------------------- opaque type requires that `prefix` is borrowed for `'a`
...
```
but without suggesting the lovely `help: you can add a constraint..`.
r? @estebank
A bit speculative at this stage but profiling shows that type folding
takes up a substantial amount of time during normalization which may
indicate that many types may be folded despite there being nothing to
normalize
