Add const params to Def

Co-Authored-By: Gabriel Smith <yodaldevoid@users.noreply.github.com>

src/librustc/hir/def.rs

@@ -52,6 +52,7 @@ pub enum Def {
     AssociatedExistential(DefId),
     PrimTy(hir::PrimTy),
     TyParam(DefId),
+    ConstParam(DefId),
     SelfTy(Option<DefId> /* trait */, Option<DefId> /* impl */),
     ToolMod, // e.g., `rustfmt` in `#[rustfmt::skip]`
 
@@ -265,7 +266,8 @@ impl Def {
             Def::Fn(id) | Def::Mod(id) | Def::Static(id, _) |
             Def::Variant(id) | Def::VariantCtor(id, ..) | Def::Enum(id) |
             Def::TyAlias(id) | Def::TraitAlias(id) |
-            Def::AssociatedTy(id) | Def::TyParam(id) | Def::Struct(id) | Def::StructCtor(id, ..) |
+            Def::AssociatedTy(id) | Def::TyParam(id) | Def::ConstParam(id) | Def::Struct(id) |
+            Def::StructCtor(id, ..) |
             Def::Union(id) | Def::Trait(id) | Def::Method(id) | Def::Const(id) |
             Def::AssociatedConst(id) | Def::Macro(id, ..) |
             Def::Existential(id) | Def::AssociatedExistential(id) | Def::ForeignTy(id) => {
@@ -322,6 +324,7 @@ impl Def {
             Def::Const(..) => "constant",
             Def::AssociatedConst(..) => "associated constant",
             Def::TyParam(..) => "type parameter",
+            Def::ConstParam(..) => "const parameter",
             Def::PrimTy(..) => "builtin type",
             Def::Local(..) => "local variable",
             Def::Upvar(..) => "closure capture",

src/librustc/hir/map/def_collector.rs

@@ -218,6 +218,7 @@ impl<'a> visit::Visitor<'a> for DefCollector<'a> {
         let def_path_data = match param.kind {
             GenericParamKind::Lifetime { .. } => DefPathData::LifetimeParam(name),
             GenericParamKind::Type { .. } => DefPathData::TypeParam(name),
+            GenericParamKind::Const { .. } => DefPathData::ConstParam(name),
         };
         self.create_def(param.id, def_path_data, REGULAR_SPACE, param.ident.span);
 

src/librustc/hir/map/definitions.rs

@@ -356,10 +356,12 @@ pub enum DefPathData {
     /// A closure expression
     ClosureExpr,
     // Subportions of items
-    /// A type parameter (generic parameter)
+    /// A type (generic) parameter
     TypeParam(InternedString),
-    /// A lifetime definition
+    /// A lifetime (generic) parameter
     LifetimeParam(InternedString),
+    /// A const (generic) parameter
+    ConstParam(InternedString),
     /// A variant of a enum
     EnumVariant(InternedString),
     /// A struct field
@@ -641,6 +643,7 @@ impl DefPathData {
             MacroDef(name) |
             TypeParam(name) |
             LifetimeParam(name) |
+            ConstParam(name) |
             EnumVariant(name) |
             Field(name) |
             GlobalMetaData(name) => Some(name),
@@ -669,6 +672,7 @@ impl DefPathData {
             MacroDef(name) |
             TypeParam(name) |
             LifetimeParam(name) |
+            ConstParam(name) |
             EnumVariant(name) |
             Field(name) |
             GlobalMetaData(name) => {

src/librustc/ich/impls_hir.rs

@@ -1046,6 +1046,7 @@ impl_stable_hash_for!(enum hir::def::Def {
     AssociatedExistential(def_id),
     PrimTy(prim_ty),
     TyParam(def_id),
+    ConstParam(def_id),
     SelfTy(trait_def_id, impl_def_id),
     ForeignTy(def_id),
     Fn(def_id),

src/librustc/ty/item_path.rs

@@ -325,6 +325,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
             data @ DefPathData::Module(..) |
             data @ DefPathData::TypeParam(..) |
             data @ DefPathData::LifetimeParam(..) |
+            data @ DefPathData::ConstParam(..) |
             data @ DefPathData::EnumVariant(..) |
             data @ DefPathData::Field(..) |
             data @ DefPathData::AnonConst |

src/librustc/util/ppaux.rs

@@ -426,6 +426,7 @@ impl PrintContext {
                     DefPathData::ClosureExpr |
                     DefPathData::TypeParam(_) |
                     DefPathData::LifetimeParam(_) |
+                    DefPathData::ConstParam(_) |
                     DefPathData::Field(_) |
                     DefPathData::StructCtor |
                     DefPathData::AnonConst |

src/librustc_save_analysis/lib.rs

@@ -762,6 +762,13 @@ impl<'l, 'tcx: 'l> SaveContext<'l, 'tcx> {
                     ref_id: id_from_def_id(def_id),
                 })
             }
+            HirDef::ConstParam(def_id) => {
+                Some(Ref {
+                    kind: RefKind::Variable,
+                    span,
+                    ref_id: id_from_def_id(def_id),
+                })
+            }
             HirDef::StructCtor(def_id, _) => {
                 // This is a reference to a tuple struct where the def_id points
                 // to an invisible constructor function. That is not a very useful