bjoernager/rust
bjoernager/rust
1
Fork 0
Code Activity

Remove some special code handling TAIT being passed through if and match

Browse source 
This is not necessary for RPIT anymore, since we reverted that to using inference vars.
This commit is contained in:
Oli Scherer 2022-02-17 15:23:28 +00:00
parent 02536fe18b
commit 1f46f771a6
6 changed files with 68 additions and 27 deletions
Download patch file Download diff file Expand all files Collapse all files

28
compiler/rustc_typeck/src/check/expectation.rs
View file

@ -1,6 +1,5 @@
use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
use rustc_middle::ty::{self, Ty};
use rustc_span::DUMMY_SP;
use rustc_span::{self, Span};
use super::Expectation::*;
@ -44,7 +43,7 @@ impl<'a, 'tcx> Expectation<'tcx> {
// when checking the 'then' block which are incompatible with the
// 'else' branch.
pub(super) fn adjust_for_branches(&self, fcx: &FnCtxt<'a, 'tcx>) -> Expectation<'tcx> {
match self.strip_opaque(fcx) {
match *self {
ExpectHasType(ety) => {
let ety = fcx.shallow_resolve(ety);
if !ety.is_ty_var() { ExpectHasType(ety) } else { NoExpectation }
@ -105,35 +104,14 @@ impl<'a, 'tcx> Expectation<'tcx> {
/// for the program to type-check). `only_has_type` will return
/// such a constraint, if it exists.
pub(super) fn only_has_type(self, fcx: &FnCtxt<'a, 'tcx>) -> Option<Ty<'tcx>> {
match self.strip_opaque(fcx) {
ExpectHasType(ty) => Some(ty),
match self {
ExpectHasType(ty) => Some(fcx.resolve_vars_if_possible(ty)),
NoExpectation | ExpectCastableToType(_) | ExpectRvalueLikeUnsized(_) | IsLast(_) => {
None
}
}
}
/// We must not treat opaque types as expected types in their defining scope, as that
/// will break `fn foo() -> impl Trait { if cond { a } else { b } }` if `a` and `b` are
/// only "equal" if they coerce to a common target, like two different function items
/// coercing to a function pointer if they have the same signature.
fn strip_opaque(self, fcx: &FnCtxt<'a, 'tcx>) -> Self {
match self {
ExpectHasType(ty) => {
let ty = fcx.resolve_vars_if_possible(ty);
match *ty.kind() {
ty::Opaque(def_id, _)
if fcx.infcx.opaque_type_origin(def_id, DUMMY_SP).is_some() =>
{
NoExpectation
}
_ => self,
}
}
_ => self,
}
}
/// Like `only_has_type`, but instead of returning `None` if no
/// hard constraint exists, creates a fresh type variable.
pub(super) fn coercion_target_type(self, fcx: &FnCtxt<'a, 'tcx>, span: Span) -> Ty<'tcx> {