Move str to libcore.

src/libcore/str/mod.rs

@@ -26,10 +26,20 @@ pub mod pattern;
 #[allow(missing_docs)]
 pub mod lossy;
 
-// HACK(eddyb) private and not named `str` to avoid changing name resolution.
-#[cfg(not(bootstrap))]
-#[lang = "str"]
-struct Str([u8]);
+mod sealed {
+    // HACK(eddyb) sealed away and not named `str` to avoid changing name resolution.
+    // Only `pub` to avoid the privacy checker producing errors.
+    #[cfg(not(bootstrap))]
+    #[lang = "str"]
+    #[stable(feature = "rust1", since = "1.0.0")]
+    pub struct Str([u8]);
+
+    #[unstable(feature = "structural_match", issue = "31434")]
+    impl crate::marker::StructuralPartialEq for str {}
+
+    #[unstable(feature = "structural_match", issue = "31434")]
+    impl crate::marker::StructuralEq for str {}
+}
 
 /// Parse a value from a string
 ///

src/librustc_codegen_llvm/debuginfo/metadata.rs

@@ -573,7 +573,9 @@ pub fn type_metadata(cx: &CodegenCx<'ll, 'tcx>, t: Ty<'tcx>, usage_site_span: Sp
 
     let ptr_metadata = |ty: Ty<'tcx>| match ty.kind {
         ty::Slice(typ) => Ok(vec_slice_metadata(cx, t, typ, unique_type_id, usage_site_span)),
-        ty::Str => Ok(vec_slice_metadata(cx, t, cx.tcx.types.u8, unique_type_id, usage_site_span)),
+        ty::Adt(def, _) if def.is_str() => {
+            Ok(vec_slice_metadata(cx, t, cx.tcx.types.u8, unique_type_id, usage_site_span))
+        }
         ty::Dynamic(..) => Ok(MetadataCreationResult::new(
             trait_pointer_metadata(cx, ty, Some(t), unique_type_id),
             false,
@@ -601,7 +603,9 @@ pub fn type_metadata(cx: &CodegenCx<'ll, 'tcx>, t: Ty<'tcx>, usage_site_span: Sp
         ty::Array(typ, _) | ty::Slice(typ) => {
             fixed_vec_metadata(cx, unique_type_id, t, typ, usage_site_span)
         }
-        ty::Str => fixed_vec_metadata(cx, unique_type_id, t, cx.tcx.types.i8, usage_site_span),
+        ty::Adt(def, _) if def.is_str() => {
+            fixed_vec_metadata(cx, unique_type_id, t, cx.tcx.types.i8, usage_site_span)
+        }
         ty::Dynamic(..) => {
             MetadataCreationResult::new(trait_pointer_metadata(cx, t, None, unique_type_id), false)
         }

src/librustc_codegen_llvm/type_of.rs

@@ -58,8 +58,7 @@ fn uncached_llvm_type<'a, 'tcx>(
         // FIXME(eddyb) producing readable type names for trait objects can result
         // in problematically distinct types due to HRTB and subtyping (see #47638).
         // ty::Dynamic(..) |
-        ty::Foreign(..) |
-        ty::Str => {
+        ty::Foreign(..) => {
             let mut name = String::with_capacity(32);
             let printer = DefPathBasedNames::new(cx.tcx, true, true);
             printer.push_type_name(layout.ty, &mut name, false);

src/librustc_codegen_ssa/debuginfo/type_names.rs

@@ -36,7 +36,7 @@ pub fn push_debuginfo_type_name<'tcx>(
     match t.kind {
         ty::Bool => output.push_str("bool"),
         ty::Char => output.push_str("char"),
-        ty::Str => output.push_str("str"),
+        ty::Adt(def, _) if def.is_str() => output.push_str("str"),
         ty::Never => output.push_str("!"),
         ty::Int(int_ty) => output.push_str(int_ty.name_str()),
         ty::Uint(uint_ty) => output.push_str(uint_ty.name_str()),

src/librustc_codegen_ssa/glue.rs

@@ -25,7 +25,7 @@ pub fn size_and_align_of_dst<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
             let vtable = info.unwrap();
             (meth::SIZE.get_usize(bx, vtable), meth::ALIGN.get_usize(bx, vtable))
         }
-        ty::Slice(_) | ty::Str => {
+        ty::Slice(_) => {
             let unit = layout.field(bx, 0);
             // The info in this case is the length of the str, so the size is that
             // times the unit size.

src/librustc_codegen_ssa/mir/place.rs

@@ -125,7 +125,7 @@ impl<'a, 'tcx, V: CodegenObject> PlaceRef<'tcx, V> {
                 return simple();
             }
             _ if !field.is_unsized() => return simple(),
-            ty::Slice(..) | ty::Str | ty::Foreign(..) => return simple(),
+            ty::Slice(..) | ty::Foreign(..) => return simple(),
             ty::Adt(def, _) => {
                 if def.repr.packed() {
                     // FIXME(eddyb) generalize the adjustment when we

src/librustc_codegen_ssa/traits/type_.rs

@@ -86,7 +86,7 @@ pub trait DerivedTypeMethods<'tcx>: BaseTypeMethods<'tcx> + MiscMethods<'tcx> {
         let tail = self.tcx().struct_tail_erasing_lifetimes(ty, param_env);
         match tail.kind {
             ty::Foreign(..) => false,
-            ty::Str | ty::Slice(..) | ty::Dynamic(..) => true,
+            ty::Slice(..) | ty::Dynamic(..) => true,
             _ => bug!("unexpected unsized tail: {:?}", tail),
         }
     }

src/librustc_infer/infer/canonical/canonicalizer.rs

@@ -403,7 +403,6 @@ impl<'cx, 'tcx> TypeFolder<'tcx> for Canonicalizer<'cx, 'tcx> {
             | ty::Uint(..)
             | ty::Float(..)
             | ty::Adt(..)
-            | ty::Str
             | ty::Error
             | ty::Array(..)
             | ty::Slice(..)

src/librustc_infer/infer/freshen.rs

@@ -194,7 +194,6 @@ impl<'a, 'tcx> TypeFolder<'tcx> for TypeFreshener<'a, 'tcx> {
             | ty::Uint(..)
             | ty::Float(..)
             | ty::Adt(..)
-            | ty::Str
             | ty::Error
             | ty::Array(..)
             | ty::Slice(..)

src/librustc_lint/types.rs

@@ -617,6 +617,12 @@ impl<'a, 'tcx> ImproperCTypesVisitor<'a, 'tcx> {
         }
 
         match ty.kind {
+            ty::Adt(def, _) if def.is_str() => FfiUnsafe {
+                ty,
+                reason: "string slices have no C equivalent",
+                help: Some("consider using `*const u8` and a length instead"),
+            },
+
             ty::Adt(def, substs) => {
                 if def.is_phantom_data() {
                     return FfiPhantom(ty);
@@ -822,12 +828,6 @@ impl<'a, 'tcx> ImproperCTypesVisitor<'a, 'tcx> {
                 FfiUnsafe { ty, reason: "trait objects have no C equivalent", help: None }
             }
 
-            ty::Str => FfiUnsafe {
-                ty,
-                reason: "string slices have no C equivalent",
-                help: Some("consider using `*const u8` and a length instead"),
-            },
-
             ty::Tuple(..) => FfiUnsafe {
                 ty,
                 reason: "tuples have unspecified layout",

src/librustc_middle/traits/query.rs

@@ -219,7 +219,6 @@ pub fn trivial_dropck_outlives<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> bool {
         | ty::GeneratorWitness(..)
         | ty::RawPtr(_)
         | ty::Ref(..)
-        | ty::Str
         | ty::Foreign(..)
         | ty::Error => true,
 

src/librustc_middle/ty/context.rs

@@ -1838,7 +1838,7 @@ macro_rules! sty_debug_print {
                 for &Interned(t) in types {
                     let variant = match t.kind {
                         ty::Bool | ty::Char | ty::Int(..) | ty::Uint(..) |
-                            ty::Float(..) | ty::Str | ty::Never => continue,
+                            ty::Float(..) | ty::Never => continue,
                         ty::Error => /* unimportant */ continue,
                         $(ty::$variant(..) => &mut $variant,)*
                     };
@@ -2165,7 +2165,9 @@ impl<'tcx> TyCtxt<'tcx> {
 
     #[inline]
     pub fn mk_str(self) -> Ty<'tcx> {
-        self.mk_ty(Str)
+        let def_id = self.require_lang_item(lang_items::StrItem, None);
+        let adt_def = self.adt_def(def_id);
+        self.mk_ty(Adt(adt_def, InternalSubsts::empty()))
     }
 
     #[inline]

src/librustc_middle/ty/diagnostics.rs

@@ -10,14 +10,14 @@ impl<'tcx> TyS<'tcx> {
         match self.kind {
             Bool
             | Char
-            | Str
             | Int(_)
             | Uint(_)
             | Float(_)
             | Infer(InferTy::IntVar(_))
             | Infer(InferTy::FloatVar(_))
             | Infer(InferTy::FreshIntTy(_))
             | Infer(InferTy::FreshFloatTy(_)) => true,
+            Adt(def, _) if def.is_str() => true,
             _ => false,
         }
     }
@@ -28,14 +28,14 @@ impl<'tcx> TyS<'tcx> {
         match self.kind {
             Bool
             | Char
-            | Str
             | Int(_)
             | Uint(_)
             | Float(_)
             | Infer(InferTy::IntVar(_))
             | Infer(InferTy::FloatVar(_))
             | Infer(InferTy::FreshIntTy(_))
             | Infer(InferTy::FreshFloatTy(_)) => true,
+            Adt(def, _) if def.is_str() => true,
             Ref(_, x, _) | Array(x, _) | Slice(x) => x.peel_refs().is_simple_ty(),
             Tuple(tys) if tys.is_empty() => true,
             _ => false,

src/librustc_middle/ty/error.rs

@@ -216,9 +216,10 @@ impl<'tcx> TypeError<'tcx> {
 impl<'tcx> ty::TyS<'tcx> {
     pub fn sort_string(&self, tcx: TyCtxt<'_>) -> Cow<'static, str> {
         match self.kind {
-            ty::Bool | ty::Char | ty::Int(_) | ty::Uint(_) | ty::Float(_) | ty::Str | ty::Never => {
+            ty::Bool | ty::Char | ty::Int(_) | ty::Uint(_) | ty::Float(_) | ty::Never => {
                 format!("`{}`", self).into()
             }
+            ty::Adt(def, _) if def.is_str() => "`str`".into(),
             ty::Tuple(ref tys) if tys.is_empty() => format!("`{}`", self).into(),
 
             ty::Adt(def, _) => format!("{} `{}`", def.descr(), tcx.def_path_str(def.did)).into(),
@@ -288,8 +289,8 @@ impl<'tcx> ty::TyS<'tcx> {
             | ty::Int(_)
             | ty::Uint(_)
             | ty::Float(_)
-            | ty::Str
             | ty::Never => "type".into(),
+            ty::Adt(def, _) if def.is_str() => "type".into(),
             ty::Tuple(ref tys) if tys.is_empty() => "unit type".into(),
             ty::Adt(def, _) => def.descr().into(),
             ty::Foreign(_) => "extern type".into(),

src/librustc_middle/ty/fast_reject.rs

@@ -28,7 +28,6 @@ where
     UintSimplifiedType(ast::UintTy),
     FloatSimplifiedType(ast::FloatTy),
     AdtSimplifiedType(D),
-    StrSimplifiedType,
     ArraySimplifiedType,
     PtrSimplifiedType,
     NeverSimplifiedType,
@@ -67,7 +66,6 @@ pub fn simplify_type(
         ty::Uint(uint_type) => Some(UintSimplifiedType(uint_type)),
         ty::Float(float_type) => Some(FloatSimplifiedType(float_type)),
         ty::Adt(def, _) => Some(AdtSimplifiedType(def.did)),
-        ty::Str => Some(StrSimplifiedType),
         ty::Array(..) | ty::Slice(_) => Some(ArraySimplifiedType),
         ty::RawPtr(_) => Some(PtrSimplifiedType),
         ty::Dynamic(ref trait_info, ..) => match trait_info.principal_def_id() {
@@ -122,7 +120,6 @@ impl<D: Copy + Debug + Ord + Eq> SimplifiedTypeGen<D> {
             UintSimplifiedType(t) => UintSimplifiedType(t),
             FloatSimplifiedType(t) => FloatSimplifiedType(t),
             AdtSimplifiedType(d) => AdtSimplifiedType(map(d)),
-            StrSimplifiedType => StrSimplifiedType,
             ArraySimplifiedType => ArraySimplifiedType,
             PtrSimplifiedType => PtrSimplifiedType,
             NeverSimplifiedType => NeverSimplifiedType,
@@ -149,7 +146,6 @@ where
         match *self {
             BoolSimplifiedType
             | CharSimplifiedType
-            | StrSimplifiedType
             | ArraySimplifiedType
             | PtrSimplifiedType
             | NeverSimplifiedType

src/librustc_middle/ty/flags.rs

@@ -67,7 +67,6 @@ impl FlagComputation {
             | &ty::Float(_)
             | &ty::Uint(_)
             | &ty::Never
-            | &ty::Str
             | &ty::Foreign(..) => {}
 
             // You might think that we could just return Error for

src/librustc_middle/ty/layout.rs

@@ -542,7 +542,7 @@ impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> {
                     ty::Foreign(..) => {
                         return Ok(tcx.intern_layout(Layout::scalar(self, data_ptr)));
                     }
-                    ty::Slice(_) | ty::Str => scalar_unit(Int(dl.ptr_sized_integer(), false)),
+                    ty::Slice(_) => scalar_unit(Int(dl.ptr_sized_integer(), false)),
                     ty::Dynamic(..) => {
                         let mut vtable = scalar_unit(Pointer);
                         vtable.valid_range = 1..=*vtable.valid_range.end();
@@ -597,14 +597,6 @@ impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> {
                     size: Size::ZERO,
                 })
             }
-            ty::Str => tcx.intern_layout(Layout {
-                variants: Variants::Single { index: VariantIdx::new(0) },
-                fields: FieldsShape::Array { stride: Size::from_bytes(1), count: 0 },
-                abi: Abi::Aggregate { sized: false },
-                largest_niche: None,
-                align: dl.i8_align,
-                size: Size::ZERO,
-            }),
 
             // Odd unit types.
             ty::FnDef(..) => univariant(&[], &ReprOptions::default(), StructKind::AlwaysSized)?,
@@ -2069,7 +2061,7 @@ where
                 }
 
                 match tcx.struct_tail_erasing_lifetimes(pointee, cx.param_env()).kind {
-                    ty::Slice(_) | ty::Str => tcx.types.usize,
+                    ty::Slice(_) => tcx.types.usize,
                     ty::Dynamic(_, _) => {
                         tcx.mk_imm_ref(tcx.lifetimes.re_static, tcx.mk_array(tcx.types.usize, 3))
                         /* FIXME: use actual fn pointers
@@ -2092,7 +2084,6 @@ where
 
             // Arrays and slices.
             ty::Array(element, _) | ty::Slice(element) => element,
-            ty::Str => tcx.types.u8,
 
             // Tuples, generators and closures.
             ty::Closure(_, ref substs) => substs.as_closure().upvar_tys().nth(i).unwrap(),

src/librustc_middle/ty/mod.rs

@@ -1864,6 +1864,8 @@ bitflags! {
         /// Indicates whether the variant list of this ADT is `#[non_exhaustive]`.
         /// (i.e., this flag is never set unless this ADT is an enum).
         const IS_VARIANT_LIST_NON_EXHAUSTIVE = 1 << 10;
+        /// Indicates whether the type is `str`.
+        const IS_STR              = 1 << 11;
     }
 }
 
@@ -2254,6 +2256,9 @@ impl<'tcx> AdtDef {
         if Some(did) == tcx.lang_items().rc() {
             flags |= AdtFlags::IS_RC;
         }
+        if Some(did) == tcx.lang_items().str_type() {
+            flags |= AdtFlags::IS_STR;
+        }
 
         AdtDef { did, variants, flags, repr }
     }
@@ -2354,6 +2359,12 @@ impl<'tcx> AdtDef {
         self.flags.contains(AdtFlags::IS_MANUALLY_DROP)
     }
 
+    /// Returns `true` if this is `str`.
+    #[inline]
+    pub fn is_str(&self) -> bool {
+        self.flags.contains(AdtFlags::IS_STR)
+    }
+
     /// Returns `true` if this type has a destructor.
     pub fn has_dtor(&self, tcx: TyCtxt<'tcx>) -> bool {
         self.destructor(tcx).is_some()

src/librustc_middle/ty/outlives.rs

@@ -138,7 +138,6 @@ fn compute_components(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>, out: &mut SmallVec<[Compo
             ty::Adt(..) |         // OutlivesNominalType
             ty::Opaque(..) |        // OutlivesNominalType (ish)
             ty::Foreign(..) |     // OutlivesNominalType
-            ty::Str |             // OutlivesScalar (ish)
             ty::Array(..) |       // ...
             ty::Slice(..) |       // ...
             ty::RawPtr(..) |      // ...

src/librustc_middle/ty/print/mod.rs

@@ -290,7 +290,6 @@ pub fn characteristic_def_id_of_type(ty: Ty<'_>) -> Option<DefId> {
         | ty::Char
         | ty::Int(_)
         | ty::Uint(_)
-        | ty::Str
         | ty::FnPtr(_)
         | ty::Projection(_)
         | ty::Placeholder(..)

src/librustc_middle/ty/print/obsolete.rs

@@ -36,7 +36,7 @@ impl DefPathBasedNames<'tcx> {
         match t.kind {
             ty::Bool => output.push_str("bool"),
             ty::Char => output.push_str("char"),
-            ty::Str => output.push_str("str"),
+            ty::Adt(def, _) if def.is_str() => output.push_str("str"),
             ty::Never => output.push_str("!"),
             ty::Int(ty) => output.push_str(ty.name_str()),
             ty::Uint(ty) => output.push_str(ty.name_str()),