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// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
//! Methods for normalizing when you don't care about regions (and
//! aren't doing type inference). If either of those things don't
//! apply to you, use `infcx.normalize(...)`.
//!
//! The methods in this file use a `TypeFolder` to recursively process
//! contents, invoking the underlying
//! `normalize_ty_after_erasing_regions` query for each type found
//! within. (This underlying query is what is cached.)
use ty::{self, Ty, TyCtxt};
use ty::fold::{TypeFoldable, TypeFolder};
impl<'cx, 'tcx> TyCtxt<'cx, 'tcx, 'tcx> {
/// Erase the regions in `value` and then fully normalize all the
/// types found within. The result will also have regions erased.
///
/// This is appropriate to use only after type-check: it assumes
/// that normalization will succeed, for example.
pub fn normalize_erasing_regions<T>(self, param_env: ty::ParamEnv<'tcx>, value: T) -> T
where
T: TypeFoldable<'tcx>,
{
debug!(
"normalize_erasing_regions::<{}>(value={:?}, param_env={:?})",
unsafe { ::std::intrinsics::type_name::<T>() },
value,
param_env,
);
// Erase first before we do the real query -- this keeps the
// cache from being too polluted.
let value = self.erase_regions(&value);
if !value.has_projections() {
value
} else {
value.fold_with(&mut NormalizeAfterErasingRegionsFolder {
tcx: self,
param_env: param_env,
})
}
}
/// If you have a `Binder<T>`, you can do this to strip out the
/// late-bound regions and then normalize the result, yielding up
/// a `T` (with regions erased). This is appropriate when the
/// binder is being instantiated at the call site.
///
/// NB. Currently, higher-ranked type bounds inhibit
/// normalization. Therefore, each time we erase them in
/// translation, we need to normalize the contents.
pub fn normalize_erasing_late_bound_regions<T>(
self,
param_env: ty::ParamEnv<'tcx>,
value: &ty::Binder<T>,
) -> T
where
T: TypeFoldable<'tcx>,
{
assert!(!value.needs_subst());
let value = self.erase_late_bound_regions(value);
self.normalize_erasing_regions(param_env, value)
}
}
struct NormalizeAfterErasingRegionsFolder<'cx, 'tcx: 'cx> {
tcx: TyCtxt<'cx, 'tcx, 'tcx>,
param_env: ty::ParamEnv<'tcx>,
}
impl<'cx, 'tcx> TypeFolder<'tcx, 'tcx> for NormalizeAfterErasingRegionsFolder<'cx, 'tcx> {
fn tcx<'a>(&'a self) -> TyCtxt<'a, 'tcx, 'tcx> {
self.tcx
}
fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> {
self.tcx.normalize_ty_after_erasing_regions(self.param_env.and(ty))
}
}
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