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Split and inline ShallowResolver::fold_ty.

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This commit is contained in:
Nicholas Nethercote 2023-02-03 12:36:44 +11:00
parent c2cf3f7b24
commit fb8e6819aa
1 changed files with 46 additions and 37 deletions
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83
compiler/rustc_infer/src/infer/mod.rs
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@ -30,7 +30,7 @@ use rustc_middle::ty::relate::RelateResult;
use rustc_middle::ty::subst::{GenericArg, GenericArgKind, InternalSubsts, SubstsRef};
use rustc_middle::ty::visit::TypeVisitable;
pub use rustc_middle::ty::IntVarValue;
use rustc_middle::ty::{self, GenericParamDefKind, InferConst, Ty, TyCtxt};
use rustc_middle::ty::{self, GenericParamDefKind, InferConst, InferTy, Ty, TyCtxt};
use rustc_middle::ty::{ConstVid, FloatVid, IntVid, TyVid};
use rustc_span::symbol::Symbol;
use rustc_span::Span;
@ -1870,43 +1870,9 @@ impl<'a, 'tcx> TypeFolder<'tcx> for ShallowResolver<'a, 'tcx> {
/// If `ty` is a type variable of some kind, resolve it one level
/// (but do not resolve types found in the result). If `typ` is
/// not a type variable, just return it unmodified.
#[inline]
fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> {
match *ty.kind() {
ty::Infer(ty::TyVar(v)) => {
// Not entirely obvious: if `typ` is a type variable,
// it can be resolved to an int/float variable, which
// can then be recursively resolved, hence the
// recursion. Note though that we prevent type
// variables from unifying to other type variables
// directly (though they may be embedded
// structurally), and we prevent cycles in any case,
// so this recursion should always be of very limited
// depth.
//
// Note: if these two lines are combined into one we get
// dynamic borrow errors on `self.inner`.
let known = self.infcx.inner.borrow_mut().type_variables().probe(v).known();
known.map_or(ty, |t| self.fold_ty(t))
}
ty::Infer(ty::IntVar(v)) => self
.infcx
.inner
.borrow_mut()
.int_unification_table()
.probe_value(v)
.map_or(ty, |v| v.to_type(self.infcx.tcx)),
ty::Infer(ty::FloatVar(v)) => self
.infcx
.inner
.borrow_mut()
.float_unification_table()
.probe_value(v)
.map_or(ty, |v| v.to_type(self.infcx.tcx)),
_ => ty,
}
if let ty::Infer(v) = ty.kind() { self.fold_infer_ty(*v).unwrap_or(ty) } else { ty }
}
fn fold_const(&mut self, ct: ty::Const<'tcx>) -> ty::Const<'tcx> {
@ -1925,6 +1891,49 @@ impl<'a, 'tcx> TypeFolder<'tcx> for ShallowResolver<'a, 'tcx> {
}
}
impl<'a, 'tcx> ShallowResolver<'a, 'tcx> {
// This is separate from `fold_ty` to keep that method small and inlinable.
#[inline(never)]
fn fold_infer_ty(&mut self, v: InferTy) -> Option<Ty<'tcx>> {
match v {
ty::TyVar(v) => {
// Not entirely obvious: if `typ` is a type variable,
// it can be resolved to an int/float variable, which
// can then be recursively resolved, hence the
// recursion. Note though that we prevent type
// variables from unifying to other type variables
// directly (though they may be embedded
// structurally), and we prevent cycles in any case,
// so this recursion should always be of very limited
// depth.
//
// Note: if these two lines are combined into one we get
// dynamic borrow errors on `self.inner`.
let known = self.infcx.inner.borrow_mut().type_variables().probe(v).known();
known.map(|t| self.fold_ty(t))
}
ty::IntVar(v) => self
.infcx
.inner
.borrow_mut()
.int_unification_table()
.probe_value(v)
.map(|v| v.to_type(self.infcx.tcx)),
ty::FloatVar(v) => self
.infcx
.inner
.borrow_mut()
.float_unification_table()
.probe_value(v)
.map(|v| v.to_type(self.infcx.tcx)),
ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_) => None,
}
}
}
impl<'tcx> TypeTrace<'tcx> {
pub fn span(&self) -> Span {
self.cause.span