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Use ObligationCtxt in expected_inputs_for_expected_outputs

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This commit is contained in:
Michael Goulet 2022-11-09 18:27:20 +00:00
parent cc9b259b5e
commit bdced83a2e
1 changed files with 7 additions and 26 deletions
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33
compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs
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@ -18,6 +18,7 @@ use rustc_infer::infer::canonical::{Canonical, OriginalQueryValues, QueryRespons
use rustc_infer::infer::error_reporting::TypeAnnotationNeeded::E0282;
use rustc_infer::infer::{InferOk, InferResult};
use rustc_middle::ty::adjustment::{Adjust, Adjustment, AutoBorrow, AutoBorrowMutability};
use rustc_middle::ty::error::TypeError;
use rustc_middle::ty::fold::TypeFoldable;
use rustc_middle::ty::visit::TypeVisitable;
use rustc_middle::ty::{
@ -32,9 +33,7 @@ use rustc_span::symbol::{kw, sym, Ident};
use rustc_span::{Span, DUMMY_SP};
use rustc_trait_selection::infer::InferCtxtExt as _;
use rustc_trait_selection::traits::error_reporting::TypeErrCtxtExt as _;
use rustc_trait_selection::traits::{
self, ObligationCause, ObligationCauseCode, TraitEngine, TraitEngineExt,
};
use rustc_trait_selection::traits::{self, ObligationCause, ObligationCauseCode, ObligationCtxt};
use std::collections::hash_map::Entry;
use std::slice;
@ -766,34 +765,16 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
let expect_args = self
.fudge_inference_if_ok(|| {
let ocx = ObligationCtxt::new(self);
// Attempt to apply a subtyping relationship between the formal
// return type (likely containing type variables if the function
// is polymorphic) and the expected return type.
// No argument expectations are produced if unification fails.
let origin = self.misc(call_span);
let ures = self.at(&origin, self.param_env).sup(ret_ty, formal_ret);
// FIXME(#27336) can't use ? here, Try::from_error doesn't default
// to identity so the resulting type is not constrained.
match ures {
Ok(ok) => {
// Process any obligations locally as much as
// we can. We don't care if some things turn
// out unconstrained or ambiguous, as we're
// just trying to get hints here.
let errors = self.save_and_restore_in_snapshot_flag(|_| {
let mut fulfill = <dyn TraitEngine<'_>>::new(self.tcx);
for obligation in ok.obligations {
fulfill.register_predicate_obligation(self, obligation);
}
fulfill.select_where_possible(self)
});
if !errors.is_empty() {
return Err(());
}
}
Err(_) => return Err(()),
ocx.sup(&origin, self.param_env, ret_ty, formal_ret)?;
if !ocx.select_where_possible().is_empty() {
return Err(TypeError::Mismatch);
}
// Record all the argument types, with the substitutions