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postpone evaluation of constants whose substs depend on inference vars or regions

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b-naber 2021-10-18 17:36:45 +02:00
parent 87ec5680c9
commit 7530c43b79
1 changed files with 17 additions and 3 deletions
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20
compiler/rustc_infer/src/infer/mod.rs
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@ -21,6 +21,7 @@ use rustc_hir::def_id::{DefId, LocalDefId};
use rustc_middle::infer::canonical::{Canonical, CanonicalVarValues};
use rustc_middle::infer::unify_key::{ConstVarValue, ConstVariableValue};
use rustc_middle::infer::unify_key::{ConstVariableOrigin, ConstVariableOriginKind, ToType};
use rustc_middle::mir::interpret::ErrorHandled;
use rustc_middle::mir::interpret::EvalToConstValueResult;
use rustc_middle::traits::select;
use rustc_middle::ty::error::{ExpectedFound, TypeError};
@ -1584,10 +1585,23 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
unevaluated: ty::Unevaluated<'tcx>,
span: Option<Span>,
) -> EvalToConstValueResult<'tcx> {
let mut original_values = OriginalQueryValues::default();
let canonical = self.canonicalize_query((param_env, unevaluated), &mut original_values);
let param_env = self.tcx.erase_regions(param_env);
let mut substs = unevaluated.substs(self.tcx);
substs = self.tcx.erase_regions(substs);
substs = self.resolve_vars_if_possible(substs);
// Postpone the evaluation of constants whose substs depend on inference
// variables
if substs.has_infer_types_or_consts() {
return Err(ErrorHandled::TooGeneric);
}
let unevaluated = ty::Unevaluated {
def: unevaluated.def,
substs_: Some(substs),
promoted: unevaluated.promoted,
};
let (param_env, unevaluated) = canonical.value;
// The return value is the evaluated value which doesn't contain any reference to inference
// variables, thus we don't need to substitute back the original values.
self.tcx.const_eval_resolve(param_env, unevaluated, span)