mikros/rust
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

expose default substs in param_env

Browse Source
This commit is contained in:
b-naber 2021-10-25 15:34:59 +02:00
parent aa5740c715
commit c6b69017e2
1 changed files with 12 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
compiler/rustc_ty_utils/src/ty.rs
View File

@ -247,6 +247,7 @@ fn trait_of_item(tcx: TyCtxt<'_>, def_id: DefId) -> Option<DefId> {
}
/// See `ParamEnv` struct definition for details.
#[instrument(level = "debug", skip(tcx))]
fn param_env(tcx: TyCtxt<'_>, def_id: DefId) -> ty::ParamEnv<'_> {
// The param_env of an impl Trait type is its defining function's param_env
if let Some(parent) = ty::is_impl_trait_defn(tcx, def_id) {
@ -274,9 +275,20 @@ fn param_env(tcx: TyCtxt<'_>, def_id: DefId) -> ty::ParamEnv<'_> {
predicates.extend(environment);
}
// It's important that we include the default substs in unevaluated
// constants, since `Unevaluated` instances in predicates whose substs are None
// can lead to "duplicate" caller bounds candidates during trait selection,
// duplicate in the sense that both have their default substs, but the
// candidate that resulted from a superpredicate still uses `None` in its
// `substs_` field of `Unevaluated` to indicate that it has its default substs,
// whereas the other candidate has `substs_: Some(default_substs)`, see
// issue #89334
predicates = tcx.expose_default_const_substs(predicates);
let unnormalized_env =
ty::ParamEnv::new(tcx.intern_predicates(&predicates), traits::Reveal::UserFacing);
debug!("unnormalized_env caller bounds: {:?}", unnormalized_env.caller_bounds());
let body_id = def_id
.as_local()
.map(|def_id| tcx.hir().local_def_id_to_hir_id(def_id))