bjoernager/rust
bjoernager/rust
1
Fork 0
Code Issues Pull requests Activity

Auto merge of #82159 - BoxyUwU:uwu, r=varkor

Browse source 
Use correct param_env in conservative_is_privately_uninhabited

cc `@lcnr`
r? `@varkor` since this is your FIXME that was removed ^^
This commit is contained in:
bors 2021-02-24 21:54:52 +00:00
commit 1fdadbf13a
9 changed files with 131 additions and 57 deletions
Download patch file Download diff file Expand all files Collapse all files

2
compiler/rustc_ty_utils/src/lib.rs
View file

@ -5,6 +5,8 @@
//! This API is completely unstable and subject to change.
#![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
#![feature(half_open_range_patterns)]
#![feature(exclusive_range_pattern)]
#![feature(nll)]
#![recursion_limit = "256"]

58
compiler/rustc_ty_utils/src/ty.rs
View file

@ -481,6 +481,63 @@ fn asyncness(tcx: TyCtxt<'_>, def_id: DefId) -> hir::IsAsync {
fn_like.asyncness()
}
/// Don't call this directly: use ``tcx.conservative_is_privately_uninhabited`` instead.
#[instrument(level = "debug", skip(tcx))]
pub fn conservative_is_privately_uninhabited_raw<'tcx>(
tcx: TyCtxt<'tcx>,
param_env_and: ty::ParamEnvAnd<'tcx, Ty<'tcx>>,
) -> bool {
let (param_env, ty) = param_env_and.into_parts();
match ty.kind() {
ty::Never => {
debug!("ty::Never =>");
true
}
ty::Adt(def, _) if def.is_union() => {
debug!("ty::Adt(def, _) if def.is_union() =>");
// For now, `union`s are never considered uninhabited.
false
}
ty::Adt(def, substs) => {
debug!("ty::Adt(def, _) if def.is_not_union() =>");
// Any ADT is uninhabited if either:
// (a) It has no variants (i.e. an empty `enum`);
// (b) Each of its variants (a single one in the case of a `struct`) has at least
// one uninhabited field.
def.variants.iter().all(|var| {
var.fields.iter().any(|field| {
let ty = tcx.type_of(field.did).subst(tcx, substs);
tcx.conservative_is_privately_uninhabited(param_env.and(ty))
})
})
}
ty::Tuple(..) => {
debug!("ty::Tuple(..) =>");
ty.tuple_fields().any(|ty| tcx.conservative_is_privately_uninhabited(param_env.and(ty)))
}
ty::Array(ty, len) => {
debug!("ty::Array(ty, len) =>");
match len.try_eval_usize(tcx, param_env) {
Some(0) | None => false,
// If the array is definitely non-empty, it's uninhabited if
// the type of its elements is uninhabited.
Some(1..) => tcx.conservative_is_privately_uninhabited(param_env.and(ty)),
}
}
ty::Ref(..) => {
debug!("ty::Ref(..) =>");
// References to uninitialised memory is valid for any type, including
// uninhabited types, in unsafe code, so we treat all references as
// inhabited.
false
}
_ => {
debug!("_ =>");
false
}
}
}
pub fn provide(providers: &mut ty::query::Providers) {
*providers = ty::query::Providers {
asyncness,
@ -498,6 +555,7 @@ pub fn provide(providers: &mut ty::query::Providers) {
instance_def_size_estimate,
issue33140_self_ty,
impl_defaultness,
conservative_is_privately_uninhabited: conservative_is_privately_uninhabited_raw,
..*providers
};
}