rust-lang · JohnTitor · May 22, 2022 · May 31, 2022 · Jun 7, 2022 · Jun 7, 2022
diff --git a/compiler/rustc_parse/src/parser/expr.rs b/compiler/rustc_parse/src/parser/expr.rs
@@ -2718,13 +2718,12 @@ impl<'a> Parser<'a> {
                     ));
                 }
                 this.expect_one_of(&[token::Comma], &[token::CloseDelim(Delimiter::Brace)])
-                    .map_err(|mut err| {
-                        match (sm.span_to_lines(expr.span), sm.span_to_lines(arm_start_span)) {
-                            (Ok(ref expr_lines), Ok(ref arm_start_lines))
-                                if arm_start_lines.lines[0].end_col
-                                    == expr_lines.lines[0].end_col
-                                    && expr_lines.lines.len() == 2
-                                    && this.token == token::FatArrow =>
+                    .or_else(|mut err| {
+                        if this.token == token::FatArrow {
+                            if let Ok(expr_lines) = sm.span_to_lines(expr.span)
+                            && let Ok(arm_start_lines) = sm.span_to_lines(arm_start_span)
+                            && arm_start_lines.lines[0].end_col == expr_lines.lines[0].end_col
+                            && expr_lines.lines.len() == 2
                             {
                                 // We check whether there's any trailing code in the parse span,
                                 // if there isn't, we very likely have the following:
@@ -2743,15 +2742,41 @@ impl<'a> Parser<'a> {
                                     ",".to_owned(),
                                     Applicability::MachineApplicable,
                                 );
+                                return Err(err);
                             }
-                            _ => {
-                                err.span_label(
-                                    arrow_span,
-                                    "while parsing the `match` arm starting here",
-                                );
+                        } else {
+                            // FIXME(compiler-errors): We could also recover `; PAT =>` here
+
+                            // Try to parse a following `PAT =>`, if successful
+                            // then we should recover.
+                            let mut snapshot = this.create_snapshot_for_diagnostic();
+                            let pattern_follows = snapshot
+                                .parse_pat_allow_top_alt(
+                                    None,
+                                    RecoverComma::Yes,
+                                    RecoverColon::Yes,
+                                    CommaRecoveryMode::EitherTupleOrPipe,
+                                )
+                                .map_err(|err| err.cancel())
+                                .is_ok();
+                            if pattern_follows && snapshot.check(&TokenKind::FatArrow) {
+                                err.cancel();
+                                this.struct_span_err(
+                                    hi.shrink_to_hi(),
+                                    "expected `,` following `match` arm",
+                                )
+                                .span_suggestion(
+                                    hi.shrink_to_hi(),
+                                    "missing a comma here to end this `match` arm",
+                                    ",".to_owned(),
+                                    Applicability::MachineApplicable,
+                                )
+                                .emit();
+                                return Ok(true);
                             }
                         }
-                        err
+                        err.span_label(arrow_span, "while parsing the `match` arm starting here");
+                        Err(err)
                     })?;
             } else {
                 this.eat(&token::Comma);

diff --git a/compiler/rustc_parse/src/parser/item.rs b/compiler/rustc_parse/src/parser/item.rs
@@ -204,25 +204,7 @@ impl<'a> Parser<'a> {
         let mut def = || mem::replace(def, Defaultness::Final);
 
         let info = if self.eat_keyword(kw::Use) {
-            // USE ITEM
-            let tree = self.parse_use_tree()?;
-
-            // If wildcard or glob-like brace syntax doesn't have `;`,
-            // the user may not know `*` or `{}` should be the last.
-            if let Err(mut e) = self.expect_semi() {
-                match tree.kind {
-                    UseTreeKind::Glob => {
-                        e.note("the wildcard token must be last on the path");
-                    }
-                    UseTreeKind::Nested(..) => {
-                        e.note("glob-like brace syntax must be last on the path");
-                    }
-                    _ => (),
-                }
-                return Err(e);
-            }
-
-            (Ident::empty(), ItemKind::Use(tree))
+            self.parse_use_item()?
         } else if self.check_fn_front_matter(def_final) {
             // FUNCTION ITEM
             let (ident, sig, generics, body) = self.parse_fn(attrs, fn_parse_mode, lo, vis)?;
@@ -288,7 +270,12 @@ impl<'a> Parser<'a> {
         } else if let IsMacroRulesItem::Yes { has_bang } = self.is_macro_rules_item() {
             // MACRO_RULES ITEM
             self.parse_item_macro_rules(vis, has_bang)?
-        } else if vis.kind.is_pub() && self.isnt_macro_invocation() {
+        } else if self.isnt_macro_invocation()
+            && (self.token.is_ident_named(Symbol::intern("import"))
+                || self.token.is_ident_named(Symbol::intern("using")))
+        {
+            return self.recover_import_as_use();
+        } else if self.isnt_macro_invocation() && vis.kind.is_pub() {
             self.recover_missing_kw_before_item()?;
             return Ok(None);
         } else if macros_allowed && self.check_path() {
@@ -300,6 +287,48 @@ impl<'a> Parser<'a> {
         Ok(Some(info))
     }
 
+    fn recover_import_as_use(&mut self) -> PResult<'a, Option<(Ident, ItemKind)>> {
+        let span = self.token.span;
+        let token_name = super::token_descr(&self.token);
+        let snapshot = self.create_snapshot_for_diagnostic();
+        self.bump();
+        match self.parse_use_item() {
+            Ok(u) => {
+                self.struct_span_err(span, format!("expected item, found {token_name}"))
+                    .span_suggestion_short(
+                        span,
+                        "items are imported using the `use` keyword",
+                        "use".to_owned(),
+                        Applicability::MachineApplicable,
+                    )
+                    .emit();
+                Ok(Some(u))
+            }
+            Err(e) => {
+                e.cancel();
+                self.restore_snapshot(snapshot);
+                Ok(None)
+            }
+        }
+    }
+
+    fn parse_use_item(&mut self) -> PResult<'a, (Ident, ItemKind)> {
+        let tree = self.parse_use_tree()?;
+        if let Err(mut e) = self.expect_semi() {
+            match tree.kind {
+                UseTreeKind::Glob => {
+                    e.note("the wildcard token must be last on the path");
+                }
+                UseTreeKind::Nested(..) => {
+                    e.note("glob-like brace syntax must be last on the path");
+                }
+                _ => (),
+            }
+            return Err(e);
+        }
+        Ok((Ident::empty(), ItemKind::Use(tree)))
+    }
+
     /// When parsing a statement, would the start of a path be an item?
     pub(super) fn is_path_start_item(&mut self) -> bool {
         self.is_kw_followed_by_ident(kw::Union) // no: `union::b`, yes: `union U { .. }`

diff --git a/compiler/rustc_trait_selection/src/traits/util.rs b/compiler/rustc_trait_selection/src/traits/util.rs
@@ -304,22 +304,24 @@ pub fn get_vtable_index_of_object_method<'tcx, N>(
     tcx: TyCtxt<'tcx>,
     object: &super::ImplSourceObjectData<'tcx, N>,
     method_def_id: DefId,
-) -> usize {
+) -> Option<usize> {
     let existential_trait_ref = object
         .upcast_trait_ref
         .map_bound(|trait_ref| ty::ExistentialTraitRef::erase_self_ty(tcx, trait_ref));
     let existential_trait_ref = tcx.erase_regions(existential_trait_ref);
+
     // Count number of methods preceding the one we are selecting and
     // add them to the total offset.
-    let index = tcx
+    if let Some(index) = tcx
         .own_existential_vtable_entries(existential_trait_ref)
         .iter()
         .copied()
         .position(|def_id| def_id == method_def_id)
-        .unwrap_or_else(|| {
-            bug!("get_vtable_index_of_object_method: {:?} was not found", method_def_id);
-        });
-    object.vtable_base + index
+    {
+        Some(object.vtable_base + index)
+    } else {
+        None
+    }
 }
 
 pub fn closure_trait_ref_and_return_type<'tcx>(

diff --git a/compiler/rustc_ty_utils/src/instance.rs b/compiler/rustc_ty_utils/src/instance.rs
@@ -347,11 +347,15 @@ fn resolve_associated_item<'tcx>(
             _ => None,
         },
         traits::ImplSource::Object(ref data) => {
-            let index = traits::get_vtable_index_of_object_method(tcx, data, trait_item_id);
-            Some(Instance {
-                def: ty::InstanceDef::Virtual(trait_item_id, index),
-                substs: rcvr_substs,
-            })
+            if let Some(index) = traits::get_vtable_index_of_object_method(tcx, data, trait_item_id)
+            {
+                Some(Instance {
+                    def: ty::InstanceDef::Virtual(trait_item_id, index),
+                    substs: rcvr_substs,
+                })
+            } else {
+                None
+            }
         }
         traits::ImplSource::Builtin(..) => {
             if Some(trait_ref.def_id) == tcx.lang_items().clone_trait() {

diff --git a/library/alloc/tests/lib.rs b/library/alloc/tests/lib.rs
@@ -7,7 +7,6 @@
 #![feature(const_convert)]
 #![feature(const_cow_is_borrowed)]
 #![feature(const_heap)]
-#![feature(const_intrinsic_copy)]
 #![feature(const_mut_refs)]
 #![feature(const_nonnull_slice_from_raw_parts)]
 #![feature(const_ptr_write)]

diff --git a/library/core/src/intrinsics.rs b/library/core/src/intrinsics.rs
@@ -2118,11 +2118,11 @@ pub(crate) fn is_nonoverlapping<T>(src: *const T, dst: *const T, count: usize) -
 /// [`Vec::append`]: ../../std/vec/struct.Vec.html#method.append
 #[doc(alias = "memcpy")]
 #[stable(feature = "rust1", since = "1.0.0")]
-#[rustc_const_unstable(feature = "const_intrinsic_copy", issue = "80697")]
+#[rustc_const_stable(feature = "const_intrinsic_copy", since = "1.63.0")]
 #[inline]
 pub const unsafe fn copy_nonoverlapping<T>(src: *const T, dst: *mut T, count: usize) {
     extern "rust-intrinsic" {
-        #[rustc_const_unstable(feature = "const_intrinsic_copy", issue = "80697")]
+        #[rustc_const_stable(feature = "const_intrinsic_copy", since = "1.63.0")]
         pub fn copy_nonoverlapping<T>(src: *const T, dst: *mut T, count: usize);
     }
 
@@ -2200,11 +2200,11 @@ pub const unsafe fn copy_nonoverlapping<T>(src: *const T, dst: *mut T, count: us
 /// ```
 #[doc(alias = "memmove")]
 #[stable(feature = "rust1", since = "1.0.0")]
-#[rustc_const_unstable(feature = "const_intrinsic_copy", issue = "80697")]
+#[rustc_const_stable(feature = "const_intrinsic_copy", since = "1.63.0")]
 #[inline]
 pub const unsafe fn copy<T>(src: *const T, dst: *mut T, count: usize) {
     extern "rust-intrinsic" {
-        #[rustc_const_unstable(feature = "const_intrinsic_copy", issue = "80697")]
+        #[rustc_const_stable(feature = "const_intrinsic_copy", since = "1.63.0")]
         fn copy<T>(src: *const T, dst: *mut T, count: usize);
     }
 

diff --git a/library/core/src/lib.rs b/library/core/src/lib.rs
@@ -114,7 +114,6 @@
 #![feature(const_convert)]
 #![feature(const_inherent_unchecked_arith)]
 #![feature(const_int_unchecked_arith)]
-#![feature(const_intrinsic_copy)]
 #![feature(const_intrinsic_forget)]
 #![feature(const_likely)]
 #![feature(const_maybe_uninit_uninit_array)]

diff --git a/library/core/src/ptr/const_ptr.rs b/library/core/src/ptr/const_ptr.rs
@@ -1199,7 +1199,7 @@ impl<T: ?Sized> *const T {
     /// See [`ptr::copy`] for safety concerns and examples.
     ///
     /// [`ptr::copy`]: crate::ptr::copy()
-    #[rustc_const_unstable(feature = "const_intrinsic_copy", issue = "80697")]
+    #[rustc_const_stable(feature = "const_intrinsic_copy", since = "1.63.0")]
     #[stable(feature = "pointer_methods", since = "1.26.0")]
     #[inline]
     pub const unsafe fn copy_to(self, dest: *mut T, count: usize)
@@ -1218,7 +1218,7 @@ impl<T: ?Sized> *const T {
     /// See [`ptr::copy_nonoverlapping`] for safety concerns and examples.
     ///
     /// [`ptr::copy_nonoverlapping`]: crate::ptr::copy_nonoverlapping()
-    #[rustc_const_unstable(feature = "const_intrinsic_copy", issue = "80697")]
+    #[rustc_const_stable(feature = "const_intrinsic_copy", since = "1.63.0")]
     #[stable(feature = "pointer_methods", since = "1.26.0")]
     #[inline]
     pub const unsafe fn copy_to_nonoverlapping(self, dest: *mut T, count: usize)

diff --git a/library/core/src/ptr/mod.rs b/library/core/src/ptr/mod.rs
@@ -1136,7 +1136,7 @@ pub const unsafe fn read<T>(src: *const T) -> T {
     // We are calling the intrinsics directly to avoid function calls in the generated code
     // as `intrinsics::copy_nonoverlapping` is a wrapper function.
     extern "rust-intrinsic" {
-        #[rustc_const_unstable(feature = "const_intrinsic_copy", issue = "80697")]
+        #[rustc_const_stable(feature = "const_intrinsic_copy", since = "1.63.0")]
         fn copy_nonoverlapping<T>(src: *const T, dst: *mut T, count: usize);
     }
 
@@ -1331,7 +1331,7 @@ pub const unsafe fn write<T>(dst: *mut T, src: T) {
     // We are calling the intrinsics directly to avoid function calls in the generated code
     // as `intrinsics::copy_nonoverlapping` is a wrapper function.
     extern "rust-intrinsic" {
-        #[rustc_const_unstable(feature = "const_intrinsic_copy", issue = "80697")]
+        #[rustc_const_stable(feature = "const_intrinsic_copy", since = "1.63.0")]
         fn copy_nonoverlapping<T>(src: *const T, dst: *mut T, count: usize);
     }
 

diff --git a/library/core/src/ptr/mut_ptr.rs b/library/core/src/ptr/mut_ptr.rs
@@ -1311,7 +1311,7 @@ impl<T: ?Sized> *mut T {
     /// See [`ptr::copy`] for safety concerns and examples.
     ///
     /// [`ptr::copy`]: crate::ptr::copy()
-    #[rustc_const_unstable(feature = "const_intrinsic_copy", issue = "80697")]
+    #[rustc_const_stable(feature = "const_intrinsic_copy", since = "1.63.0")]
     #[stable(feature = "pointer_methods", since = "1.26.0")]
     #[inline(always)]
     pub const unsafe fn copy_to(self, dest: *mut T, count: usize)
@@ -1330,7 +1330,7 @@ impl<T: ?Sized> *mut T {
     /// See [`ptr::copy_nonoverlapping`] for safety concerns and examples.
     ///
     /// [`ptr::copy_nonoverlapping`]: crate::ptr::copy_nonoverlapping()
-    #[rustc_const_unstable(feature = "const_intrinsic_copy", issue = "80697")]
+    #[rustc_const_stable(feature = "const_intrinsic_copy", since = "1.63.0")]
     #[stable(feature = "pointer_methods", since = "1.26.0")]
     #[inline(always)]
     pub const unsafe fn copy_to_nonoverlapping(self, dest: *mut T, count: usize)
@@ -1349,7 +1349,7 @@ impl<T: ?Sized> *mut T {
     /// See [`ptr::copy`] for safety concerns and examples.
     ///
     /// [`ptr::copy`]: crate::ptr::copy()
-    #[rustc_const_unstable(feature = "const_intrinsic_copy", issue = "80697")]
+    #[rustc_const_stable(feature = "const_intrinsic_copy", since = "1.63.0")]
     #[stable(feature = "pointer_methods", since = "1.26.0")]
     #[inline(always)]
     pub const unsafe fn copy_from(self, src: *const T, count: usize)
@@ -1368,7 +1368,7 @@ impl<T: ?Sized> *mut T {
     /// See [`ptr::copy_nonoverlapping`] for safety concerns and examples.
     ///
     /// [`ptr::copy_nonoverlapping`]: crate::ptr::copy_nonoverlapping()
-    #[rustc_const_unstable(feature = "const_intrinsic_copy", issue = "80697")]
+    #[rustc_const_stable(feature = "const_intrinsic_copy", since = "1.63.0")]
     #[stable(feature = "pointer_methods", since = "1.26.0")]
     #[inline(always)]
     pub const unsafe fn copy_from_nonoverlapping(self, src: *const T, count: usize)

diff --git a/library/core/tests/ptr.rs b/library/core/tests/ptr.rs
@@ -19,6 +19,7 @@ fn test_const_from_raw_parts() {
 #[test]
 fn test() {
     unsafe {
+        #[repr(C)]
         struct Pair {
             fst: isize,
             snd: isize,

diff --git a/src/test/ui/consts/copy-intrinsic.rs b/src/test/ui/consts/copy-intrinsic.rs
@@ -2,14 +2,14 @@
 
 // ignore-tidy-linelength
 #![feature(intrinsics, staged_api)]
-#![feature(const_mut_refs, const_intrinsic_copy)]
+#![feature(const_mut_refs)]
 use std::mem;
 
 extern "rust-intrinsic" {
-    #[rustc_const_unstable(feature = "const_intrinsic_copy", issue = "80697")]
+    #[rustc_const_stable(feature = "const_intrinsic_copy", since = "1.63.0")]
     fn copy_nonoverlapping<T>(src: *const T, dst: *mut T, count: usize);
 
-    #[rustc_const_unstable(feature = "const_intrinsic_copy", issue = "80697")]
+    #[rustc_const_stable(feature = "const_intrinsic_copy", since = "1.63.0")]
     fn copy<T>(src: *const T, dst: *mut T, count: usize);
 }
 

diff --git a/src/test/ui/consts/intrinsic_without_const_stab.rs b/src/test/ui/consts/intrinsic_without_const_stab.rs
@@ -1,8 +1,8 @@
-#![feature(intrinsics, staged_api, const_intrinsic_copy)]
+#![feature(intrinsics, staged_api)]
 #![stable(feature = "core", since = "1.6.0")]
 
 #[stable(feature = "rust1", since = "1.0.0")]
-#[rustc_const_unstable(feature = "const_intrinsic_copy", issue = "80697")]
+#[rustc_const_stable(feature = "const_intrinsic_copy", since = "1.63.0")]
 #[inline]
 pub const unsafe fn copy<T>(src: *const T, dst: *mut T, count: usize) {
     // Const stability attributes are not inherited from parent items.

diff --git a/src/test/ui/consts/intrinsic_without_const_stab_fail.rs b/src/test/ui/consts/intrinsic_without_const_stab_fail.rs
@@ -1,12 +1,12 @@
-#![feature(intrinsics, staged_api, const_intrinsic_copy)]
+#![feature(intrinsics, staged_api)]
 #![stable(feature = "core", since = "1.6.0")]
 
 extern "rust-intrinsic" {
     fn copy<T>(src: *const T, dst: *mut T, count: usize);
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-#[rustc_const_unstable(feature = "const_intrinsic_copy", issue = "80697")]
+#[rustc_const_stable(feature = "const_intrinsic_copy", since = "1.63.0")]
 #[inline]
 pub const unsafe fn stuff<T>(src: *const T, dst: *mut T, count: usize) {
     unsafe { copy(src, dst, count) } //~ ERROR cannot call non-const fn

diff --git a/src/test/ui/did_you_mean/use_instead_of_import.fixed b/src/test/ui/did_you_mean/use_instead_of_import.fixed
@@ -0,0 +1,15 @@
+// run-rustfix
+
+use std::{
+    //~^ ERROR expected item, found `import`
+    io::Write,
+    rc::Rc,
+};
+
+pub use std::io;
+//~^ ERROR expected item, found `using`
+
+fn main() {
+    let x = Rc::new(1);
+    let _ = write!(io::stdout(), "{:?}", x);
+}