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Auto merge of #103695 - LYF1999:yf/103563, r=lcnr

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fix: Unexpected trait bound not satisfied in HRTB and Associated Type

fix https://github.com/rust-lang/rust/issues/103563
This commit is contained in:
bors 2023-02-14 10:01:19 +00:00
commit 9bb6e60d1f
2 changed files with 121 additions and 1 deletions
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47
compiler/rustc_trait_selection/src/traits/select/mod.rs
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@ -27,6 +27,7 @@ use super::{
use crate::infer::{InferCtxt, InferOk, TypeFreshener};
use crate::traits::error_reporting::TypeErrCtxtExt;
use crate::traits::project::try_normalize_with_depth_to;
use crate::traits::project::ProjectAndUnifyResult;
use crate::traits::project::ProjectionCacheKeyExt;
use crate::traits::ProjectionCacheKey;
@ -1049,7 +1050,51 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
return Ok(cycle_result);
}
let (result, dep_node) = self.in_task(|this| this.evaluate_stack(&stack));
let (result, dep_node) = self.in_task(|this| {
let mut result = this.evaluate_stack(&stack)?;
// fix issue #103563, we don't normalize
// nested obligations which produced by `TraitDef` candidate
// (i.e. using bounds on assoc items as assumptions).
// because we don't have enough information to
// normalize these obligations before evaluating.
// so we will try to normalize the obligation and evaluate again.
// we will replace it with new solver in the future.
if EvaluationResult::EvaluatedToErr == result
&& fresh_trait_pred.has_projections()
&& fresh_trait_pred.is_global()
{
let mut nested_obligations = Vec::new();
let predicate = try_normalize_with_depth_to(
this,
param_env,
obligation.cause.clone(),
obligation.recursion_depth + 1,
obligation.predicate,
&mut nested_obligations,
);
if predicate != obligation.predicate {
let mut nested_result = EvaluationResult::EvaluatedToOk;
for obligation in nested_obligations {
nested_result = cmp::max(
this.evaluate_predicate_recursively(stack.list(), obligation)?,
nested_result,
);
}
if nested_result.must_apply_modulo_regions() {
let obligation = obligation.with(this.tcx(), predicate);
result = cmp::max(
nested_result,
this.evaluate_trait_predicate_recursively(stack.list(), obligation)?,
);
}
}
}
Ok::<_, OverflowError>(result)
});
let result = result?;
if !result.must_apply_modulo_regions() {