1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88
// 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)) } }