Thread pattern types through the HIR

Author: oli-obk

compiler/rustc_ast_lowering/src/lib.rs

@@ -1463,6 +1463,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                     }
                 }
             }
+            TyKind::Pat(ty, pat) => hir::TyKind::Pat(self.lower_ty(ty, itctx), self.lower_pat(pat)),
             TyKind::MacCall(_) => {
                 span_bug!(t.span, "`TyKind::MacCall` should have been expanded by now")
             }
@@ -1473,7 +1474,6 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                 );
                 hir::TyKind::Err(guar)
             }
-            TyKind::Pat(..) => span_bug!(t.span, "pattern types are unimplemented"),
             TyKind::Dummy => panic!("`TyKind::Dummy` should never be lowered"),
         };
 

compiler/rustc_hir/src/hir.rs

@@ -2624,6 +2624,8 @@ pub enum TyKind<'hir> {
     Infer,
     /// Placeholder for a type that has failed to be defined.
     Err(rustc_span::ErrorGuaranteed),
+    /// Pattern types (`u32 as 1..`)
+    Pat(&'hir Ty<'hir>, &'hir Pat<'hir>),
 }
 
 #[derive(Debug, Clone, Copy, HashStable_Generic)]

compiler/rustc_hir/src/intravisit.rs

@@ -882,6 +882,10 @@ pub fn walk_ty<'v, V: Visitor<'v>>(visitor: &mut V, typ: &'v Ty<'v>) -> V::Resul
         TyKind::AnonAdt(item_id) => {
             try_visit!(visitor.visit_nested_item(item_id));
         }
+        TyKind::Pat(ty, pat) => {
+            try_visit!(visitor.visit_ty(ty));
+            try_visit!(visitor.visit_pat(pat));
+        }
     }
     V::Result::output()
 }

compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs

@@ -2195,6 +2195,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                 // handled specially and will not descend into this routine.
                 self.ty_infer(None, hir_ty.span)
             }
+            hir::TyKind::Pat(..) => span_bug!(ast_ty.span, "{ast_ty:#?}"),
             hir::TyKind::Err(guar) => Ty::new_error(tcx, *guar),
         };
 

compiler/rustc_hir_pretty/src/lib.rs

@@ -330,6 +330,11 @@ impl<'a> State<'a> {
                 self.word("_");
             }
             hir::TyKind::AnonAdt(..) => self.word("/* anonymous adt */"),
+            hir::TyKind::Pat(ty, pat) => {
+                self.print_type(ty);
+                self.word(" is ");
+                self.print_pat(pat);
+            }
         }
         self.end()
     }

compiler/rustc_lint/src/non_local_def.rs

@@ -143,6 +143,7 @@ impl<'tcx> LateLintPass<'tcx> for NonLocalDefinitions {
                     | TyKind::Never
                     | TyKind::Tup(_)
                     | TyKind::Path(_)
+                    | TyKind::Pat(..)
                     | TyKind::AnonAdt(_)
                     | TyKind::OpaqueDef(_, _, _)
                     | TyKind::Typeof(_)

compiler/rustc_passes/src/hir_stats.rs

@@ -352,6 +352,7 @@ impl<'v> hir_visit::Visitor<'v> for StatCollector<'v> {
                 TraitObject,
                 Typeof,
                 Infer,
+                Pat,
                 Err
             ]
         );

src/librustdoc/clean/mod.rs

@@ -1782,6 +1782,7 @@ pub(crate) fn clean_ty<'tcx>(ty: &hir::Ty<'tcx>, cx: &mut DocContext<'tcx>) -> T
             BorrowedRef { lifetime, mutability: m.mutbl, type_: Box::new(clean_ty(m.ty, cx)) }
         }
         TyKind::Slice(ty) => Slice(Box::new(clean_ty(ty, cx))),
+        TyKind::Pat(ty, pat) => Type::Pat(Box::new(clean_ty(ty, cx)), format!("{pat:?}").into()),
         TyKind::Array(ty, ref length) => {
             let length = match length {
                 hir::ArrayLen::Infer(..) => "_".to_string(),

src/librustdoc/clean/types.rs

@@ -1475,7 +1475,9 @@ pub(crate) enum Type {
     ///
     /// This is mostly Rustdoc's version of [`hir::Path`].
     /// It has to be different because Rustdoc's [`PathSegment`] can contain cleaned generics.
-    Path { path: Path },
+    Path {
+        path: Path,
+    },
     /// A `dyn Trait` object: `dyn for<'a> Trait<'a> + Send + 'static`
     DynTrait(Vec<PolyTrait>, Option<Lifetime>),
     /// A type parameter.
@@ -1492,10 +1494,15 @@ pub(crate) enum Type {
     ///
     /// The `String` field is a stringified version of the array's length parameter.
     Array(Box<Type>, Box<str>),
+    Pat(Box<Type>, Box<str>),
     /// A raw pointer type: `*const i32`, `*mut i32`
     RawPointer(Mutability, Box<Type>),
     /// A reference type: `&i32`, `&'a mut Foo`
-    BorrowedRef { lifetime: Option<Lifetime>, mutability: Mutability, type_: Box<Type> },
+    BorrowedRef {
+        lifetime: Option<Lifetime>,
+        mutability: Mutability,
+        type_: Box<Type>,
+    },
 
     /// A qualified path to an associated item: `<Type as Trait>::Name`
     QPath(Box<QPathData>),
@@ -1692,6 +1699,7 @@ impl Type {
             BareFunction(..) => PrimitiveType::Fn,
             Slice(..) => PrimitiveType::Slice,
             Array(..) => PrimitiveType::Array,
+            Type::Pat(..) => PrimitiveType::Pat,
             RawPointer(..) => PrimitiveType::RawPointer,
             QPath(box QPathData { ref self_type, .. }) => return self_type.inner_def_id(cache),
             Generic(_) | Infer | ImplTrait(_) => return None,
@@ -1745,6 +1753,7 @@ pub(crate) enum PrimitiveType {
     Str,
     Slice,
     Array,
+    Pat,
     Tuple,
     Unit,
     RawPointer,
@@ -1895,6 +1904,7 @@ impl PrimitiveType {
             Bool => sym::bool,
             Char => sym::char,
             Array => sym::array,
+            Pat => sym::pat,
             Slice => sym::slice,
             Tuple => sym::tuple,
             Unit => sym::unit,

src/librustdoc/html/format.rs

@@ -1071,6 +1071,10 @@ fn fmt_type<'cx>(
                 write!(f, "]")
             }
         },
+        clean::Type::Pat(ref t, ref pat) => {
+            fmt::Display::fmt(&t.print(cx), f)?;
+            write!(f, " is {pat}")
+        }
         clean::Array(ref t, ref n) => match **t {
             clean::Generic(name) if !f.alternate() => primitive_link(
                 f,