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Rollup merge of #104206 - compiler-errors:ocx-more-2, r=lcnr

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Remove `save_and_restore_in_snapshot_flag`, use `ObligationCtxt` more

r? ```@lcnr```
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Dylan DPC 2022-11-12 12:02:52 +05:30 • committed by GitHub
commit 662df1ec86
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4 changed files with 119 additions and 179 deletions
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50
compiler/rustc_trait_selection/src/traits/specialize/mod.rs
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@ -10,10 +10,12 @@
//! [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/traits/specialization.html
pub mod specialization_graph;
use rustc_infer::traits::{TraitEngine, TraitEngineExt as _};
use specialization_graph::GraphExt;
use crate::errors::NegativePositiveConflict;
use crate::infer::{InferCtxt, InferOk, TyCtxtInferExt};
use crate::traits::engine::TraitEngineExt as _;
use crate::traits::select::IntercrateAmbiguityCause;
use crate::traits::{self, coherence, FutureCompatOverlapErrorKind, ObligationCause};
use rustc_data_structures::fx::FxIndexSet;
@ -200,36 +202,32 @@ fn fulfill_implication<'tcx>(
return Err(());
};
// Needs to be `in_snapshot` because this function is used to rebase
// substitutions, which may happen inside of a select within a probe.
let mut engine = <dyn TraitEngine<'tcx>>::new_in_snapshot(infcx.tcx);
// attempt to prove all of the predicates for impl2 given those for impl1
// (which are packed up in penv)
engine.register_predicate_obligations(infcx, obligations.chain(more_obligations));
infcx.save_and_restore_in_snapshot_flag(|infcx| {
let errors = traits::fully_solve_obligations(&infcx, obligations.chain(more_obligations));
match &errors[..] {
[] => {
debug!(
"fulfill_implication: an impl for {:?} specializes {:?}",
source_trait, target_trait
);
let errors = engine.select_all_or_error(infcx);
if !errors.is_empty() {
// no dice!
debug!(
"fulfill_implication: for impls on {:?} and {:?}, \
could not fulfill: {:?} given {:?}",
source_trait,
target_trait,
errors,
param_env.caller_bounds()
);
return Err(());
}
// Now resolve the *substitution* we built for the target earlier, replacing
// the inference variables inside with whatever we got from fulfillment.
Ok(infcx.resolve_vars_if_possible(target_substs))
}
errors => {
// no dice!
debug!(
"fulfill_implication: for impls on {:?} and {:?}, \
could not fulfill: {:?} given {:?}",
source_trait,
target_trait,
errors,
param_env.caller_bounds()
);
Err(())
}
}
})
debug!("fulfill_implication: an impl for {:?} specializes {:?}", source_trait, target_trait);
// Now resolve the *substitution* we built for the target earlier, replacing
// the inference variables inside with whatever we got from fulfillment.
Ok(infcx.resolve_vars_if_possible(target_substs))
}
// Query provider for `specialization_graph_of`.