bjoernager/rust
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Rollup merge of #104411 - lcnr:bivariance-nll, r=compiler-errors

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nll: correctly deal with bivariance

fixes #104409

when in a bivariant context, relating stuff should always trivially succeed. Also changes the mir validator to correctly deal with higher ranked regions.

r? types cc ``@RalfJung``
This commit is contained in:
Dylan DPC 2022-11-19 11:54:44 +05:30 • committed by GitHub
commit 00876c68c4
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10 changed files with 130 additions and 85 deletions
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26
compiler/rustc_trait_selection/src/traits/engine.rs
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@ -125,6 +125,21 @@ impl<'a, 'tcx> ObligationCtxt<'a, 'tcx> {
.map(|infer_ok| self.register_infer_ok_obligations(infer_ok))
}
/// Checks whether `expected` is a subtype of `actual`: `expected <: actual`.
pub fn sub<T: ToTrace<'tcx>>(
&self,
cause: &ObligationCause<'tcx>,
param_env: ty::ParamEnv<'tcx>,
expected: T,
actual: T,
) -> Result<(), TypeError<'tcx>> {
self.infcx
.at(cause, param_env)
.sup(expected, actual)
.map(|infer_ok| self.register_infer_ok_obligations(infer_ok))
}
/// Checks whether `expected` is a supertype of `actual`: `expected :> actual`.
pub fn sup<T: ToTrace<'tcx>>(
&self,
cause: &ObligationCause<'tcx>,
@ -132,13 +147,10 @@ impl<'a, 'tcx> ObligationCtxt<'a, 'tcx> {
expected: T,
actual: T,
) -> Result<(), TypeError<'tcx>> {
match self.infcx.at(cause, param_env).sup(expected, actual) {
Ok(InferOk { obligations, value: () }) => {
self.register_obligations(obligations);
Ok(())
}
Err(e) => Err(e),
}
self.infcx
.at(cause, param_env)
.sup(expected, actual)
.map(|infer_ok| self.register_infer_ok_obligations(infer_ok))
}
pub fn select_where_possible(&self) -> Vec<FulfillmentError<'tcx>> {