Rollup merge of #85766 - workingjubilee:file-options, r=yaahc

[rust.git] / compiler / rustc_middle / src / ty / subst.rs

diff --git a/compiler/rustc_middle/src/ty/subst.rs b/compiler/rustc_middle/src/ty/subst.rs
index 9b8d22d8eafcebc6d5fa5b2c3d3642217c1f22ab..73a8e18949de06ad6a4d8d5b3dc0c8329b5c22bf 100644 (file)
--- a/compiler/rustc_middle/src/ty/subst.rs
+++ b/compiler/rustc_middle/src/ty/subst.rs
@@ -3,7 +3,7 @@
 use crate::mir;
 use crate::ty::codec::{TyDecoder, TyEncoder};
 use crate::ty::fold::{TypeFoldable, TypeFolder, TypeVisitor};
-use crate::ty::sty::{ClosureSubsts, GeneratorSubsts};
+use crate::ty::sty::{ClosureSubsts, GeneratorSubsts, InlineConstSubsts};
 use crate::ty::{self, Lift, List, ParamConst, Ty, TyCtxt};
 
 use rustc_hir::def_id::DefId;
@@ -22,7 +22,7 @@
 
 /// An entity in the Rust type system, which can be one of
 /// several kinds (types, lifetimes, and consts).
-/// To reduce memory usage, a `GenericArg` is a interned pointer,
+/// To reduce memory usage, a `GenericArg` is an interned pointer,
 /// with the lowest 2 bits being reserved for a tag to
 /// indicate the type (`Ty`, `Region`, or `Const`) it points to.
 #[derive(Copy, Clone, PartialEq, Eq, Hash)]
@@ -204,12 +204,20 @@ pub fn as_generator(&'tcx self) -> GeneratorSubsts<'tcx> {
         GeneratorSubsts { substs: self }
     }
 
-    /// Creates a `InternalSubsts` that maps each generic parameter to itself.
+    /// Interpret these substitutions as the substitutions of an inline const.
+    /// Inline const substitutions have a particular structure controlled by the
+    /// compiler that encodes information like the inferred type;
+    /// see `ty::InlineConstSubsts` struct for more comments.
+    pub fn as_inline_const(&'tcx self) -> InlineConstSubsts<'tcx> {
+        InlineConstSubsts { substs: self }
+    }
+
+    /// Creates an `InternalSubsts` that maps each generic parameter to itself.
     pub fn identity_for_item(tcx: TyCtxt<'tcx>, def_id: DefId) -> SubstsRef<'tcx> {
         Self::for_item(tcx, def_id, |param, _| tcx.mk_param_from_def(param))
     }
 
-    /// Creates a `InternalSubsts` for generic parameter definitions,
+    /// Creates an `InternalSubsts` for generic parameter definitions,
     /// by calling closures to obtain each kind.
     /// The closures get to observe the `InternalSubsts` as they're
     /// being built, which can be used to correctly
@@ -234,7 +242,7 @@ pub fn extend_to<F>(&self, tcx: TyCtxt<'tcx>, def_id: DefId, mut mk_kind: F) ->
         })
     }
 
-    fn fill_item<F>(
+    pub fn fill_item<F>(
         substs: &mut SmallVec<[GenericArg<'tcx>; 8]>,
         tcx: TyCtxt<'tcx>,
         defs: &ty::Generics,
@@ -249,7 +257,7 @@ fn fill_item<F>(
         Self::fill_single(substs, defs, mk_kind)
     }
 
-    fn fill_single<F>(
+    pub fn fill_single<F>(
         substs: &mut SmallVec<[GenericArg<'tcx>; 8]>,
         defs: &ty::Generics,
         mk_kind: &mut F,
@@ -486,7 +494,7 @@ fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
     }
 
     fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> {
-        if !t.needs_subst() {
+        if !t.potentially_needs_subst() {
             return t;
         }
 
@@ -497,10 +505,6 @@ fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> {
     }
 
     fn fold_const(&mut self, c: &'tcx ty::Const<'tcx>) -> &'tcx ty::Const<'tcx> {
-        if !c.needs_subst() {
-            return c;
-        }
-
         if let ty::ConstKind::Param(p) = c.val {
             self.const_for_param(p, c)
         } else {