Auto merge of #59590 - Centril:rollup, r=Centril

Rollup of 7 pull requests

Successful merges:

 - #58805 (Lint for redundant imports)
 - #59506 (Use platform dependent mcount function)
 - #59519 (rustc_target: factor out common fields of non-Single Variants.)
 - #59580 (Allow closure to unsafe fn coercion)
 - #59581 (Stabilize refcell_replace_swap feature)
 - #59583 (match match match match match)
 - #59587 (Remove #[doc(hidden)] from Error::type_id)

Failed merges:

r? @ghost

src/liballoc/borrow.rs

@@ -135,7 +135,7 @@ impl<T> ToOwned for T
 /// Another example showing how to keep `Cow` in a struct:
 ///
 /// ```
-/// use std::borrow::{Cow, ToOwned};
+/// use std::borrow::Cow;
 ///
 /// struct Items<'a, X: 'a> where [X]: ToOwned<Owned = Vec<X>> {
 ///     values: Cow<'a, [X]>,

src/libcore/cell.rs

@@ -702,24 +702,21 @@ impl<T> RefCell<T> {
     /// Replaces the wrapped value with a new one computed from `f`, returning
     /// the old value, without deinitializing either one.
     ///
-    /// This function corresponds to [`std::mem::replace`](../mem/fn.replace.html).
-    ///
     /// # Panics
     ///
     /// Panics if the value is currently borrowed.
     ///
     /// # Examples
     ///
     /// ```
-    /// #![feature(refcell_replace_swap)]
     /// use std::cell::RefCell;
     /// let cell = RefCell::new(5);
     /// let old_value = cell.replace_with(|&mut old| old + 1);
     /// assert_eq!(old_value, 5);
     /// assert_eq!(cell, RefCell::new(6));
     /// ```
     #[inline]
-    #[unstable(feature = "refcell_replace_swap", issue="43570")]
+    #[stable(feature = "refcell_replace_swap", since="1.35.0")]
     pub fn replace_with<F: FnOnce(&mut T) -> T>(&self, f: F) -> T {
         let mut_borrow = &mut *self.borrow_mut();
         let replacement = f(mut_borrow);
@@ -1421,7 +1418,6 @@ impl<T: ?Sized + fmt::Display> fmt::Display for RefMut<'_, T> {
 ///
 /// ```
 /// use std::cell::UnsafeCell;
-/// use std::marker::Sync;
 ///
 /// # #[allow(dead_code)]
 /// struct NotThreadSafe<T> {

src/libcore/tests/lib.rs

@@ -16,7 +16,6 @@
 #![feature(pattern)]
 #![feature(range_is_empty)]
 #![feature(raw)]
-#![feature(refcell_replace_swap)]
 #![feature(slice_patterns)]
 #![feature(sort_internals)]
 #![feature(specialization)]

src/librustc/lib.rs

@@ -45,7 +45,6 @@
 #![feature(proc_macro_internals)]
 #![feature(optin_builtin_traits)]
 #![feature(range_is_empty)]
-#![feature(refcell_replace_swap)]
 #![feature(rustc_diagnostic_macros)]
 #![feature(rustc_attrs)]
 #![feature(slice_patterns)]

src/librustc/lint/builtin.rs

@@ -483,6 +483,7 @@ pub enum BuiltinLintDiagnostics {
     UnknownCrateTypes(Span, String, String),
     UnusedImports(String, Vec<(Span, String)>),
     NestedImplTrait { outer_impl_trait_span: Span, inner_impl_trait_span: Span },
+    RedundantImport(Vec<(Span, bool)>, ast::Ident),
 }
 
 impl BuiltinLintDiagnostics {
@@ -579,6 +580,15 @@ impl BuiltinLintDiagnostics {
                 db.span_label(outer_impl_trait_span, "outer `impl Trait`");
                 db.span_label(inner_impl_trait_span, "nested `impl Trait` here");
             }
+            BuiltinLintDiagnostics::RedundantImport(spans, ident) => {
+                for (span, is_imported) in spans {
+                    let introduced = if is_imported { "imported" } else { "defined" };
+                    db.span_label(
+                        span,
+                        format!("the item `{}` is already {} here", ident, introduced)
+                    );
+                }
+            }
         }
     }
 }

src/librustc/middle/expr_use_visitor.rs

@@ -707,7 +707,7 @@ impl<'a, 'gcx, 'tcx> ExprUseVisitor<'a, 'gcx, 'tcx> {
                 adjustment::Adjust::NeverToAny |
                 adjustment::Adjust::ReifyFnPointer |
                 adjustment::Adjust::UnsafeFnPointer |
-                adjustment::Adjust::ClosureFnPointer |
+                adjustment::Adjust::ClosureFnPointer(_) |
                 adjustment::Adjust::MutToConstPointer |
                 adjustment::Adjust::Unsize => {
                     // Creating a closure/fn-pointer or unsizing consumes

src/librustc/middle/mem_categorization.rs

@@ -621,7 +621,7 @@ impl<'a, 'gcx, 'tcx> MemCategorizationContext<'a, 'gcx, 'tcx> {
             adjustment::Adjust::NeverToAny |
             adjustment::Adjust::ReifyFnPointer |
             adjustment::Adjust::UnsafeFnPointer |
-            adjustment::Adjust::ClosureFnPointer |
+            adjustment::Adjust::ClosureFnPointer(_) |
             adjustment::Adjust::MutToConstPointer |
             adjustment::Adjust::Borrow(_) |
             adjustment::Adjust::Unsize => {

src/librustc/mir/mod.rs

@@ -2247,8 +2247,9 @@ pub enum CastKind {
     /// Converts unique, zero-sized type for a fn to fn()
     ReifyFnPointer,
 
-    /// Converts non capturing closure to fn()
-    ClosureFnPointer,
+    /// Converts non capturing closure to fn() or unsafe fn().
+    /// It cannot convert a closure that requires unsafe.
+    ClosureFnPointer(hir::Unsafety),
 
     /// Converts safe fn() to unsafe fn()
     UnsafeFnPointer,

src/librustc/ty/adjustment.rs

@@ -62,8 +62,9 @@ pub enum Adjust<'tcx> {
     /// Go from a safe fn pointer to an unsafe fn pointer.
     UnsafeFnPointer,
 
-    /// Go from a non-capturing closure to an fn pointer.
-    ClosureFnPointer,
+    /// Go from a non-capturing closure to an fn pointer or an unsafe fn pointer.
+    /// It cannot convert a closure that requires unsafe.
+    ClosureFnPointer(hir::Unsafety),
 
     /// Go from a mut raw pointer to a const raw pointer.
     MutToConstPointer,

src/librustc/ty/context.rs

@@ -2441,7 +2441,11 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
     /// type with the same signature. Detuples and so forth -- so
     /// e.g., if we have a sig with `Fn<(u32, i32)>` then you would get
     /// a `fn(u32, i32)`.
-    pub fn coerce_closure_fn_ty(self, sig: PolyFnSig<'tcx>) -> Ty<'tcx> {
+    /// `unsafety` determines the unsafety of the `fn` type. If you pass
+    /// `hir::Unsafety::Unsafe` in the previous example, then you would get
+    /// an `unsafe fn (u32, i32)`.
+    /// It cannot convert a closure that requires unsafe.
+    pub fn coerce_closure_fn_ty(self, sig: PolyFnSig<'tcx>, unsafety: hir::Unsafety) -> Ty<'tcx> {
         let converted_sig = sig.map_bound(|s| {
             let params_iter = match s.inputs()[0].sty {
                 ty::Tuple(params) => {
@@ -2453,7 +2457,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
                 params_iter,
                 s.output(),
                 s.c_variadic,
-                hir::Unsafety::Normal,
+                unsafety,
                 abi::Abi::Rust,
             )
         });

src/librustc/ty/layout.rs

@@ -913,11 +913,13 @@ impl<'a, 'tcx> LayoutCx<'tcx, TyCtxt<'a, 'tcx, 'tcx>> {
                             }
 
                             return Ok(tcx.intern_layout(LayoutDetails {
-                                variants: Variants::NicheFilling {
-                                    dataful_variant: i,
-                                    niche_variants,
-                                    niche: niche_scalar,
-                                    niche_start,
+                                variants: Variants::Multiple {
+                                    discr: niche_scalar,
+                                    discr_kind: DiscriminantKind::Niche {
+                                        dataful_variant: i,
+                                        niche_variants,
+                                        niche_start,
+                                    },
                                     variants: st,
                                 },
                                 fields: FieldPlacement::Arbitrary {
@@ -1137,8 +1139,9 @@ impl<'a, 'tcx> LayoutCx<'tcx, TyCtxt<'a, 'tcx, 'tcx>> {
                 }
 
                 tcx.intern_layout(LayoutDetails {
-                    variants: Variants::Tagged {
-                        tag,
+                    variants: Variants::Multiple {
+                        discr: tag,
+                        discr_kind: DiscriminantKind::Tag,
                         variants: layout_variants,
                     },
                     fields: FieldPlacement::Arbitrary {
@@ -1293,8 +1296,7 @@ impl<'a, 'tcx> LayoutCx<'tcx, TyCtxt<'a, 'tcx, 'tcx>> {
                 }
             }
 
-            Variants::NicheFilling { .. } |
-            Variants::Tagged { .. } => {
+            Variants::Multiple { ref discr, ref discr_kind, .. } => {
                 debug!("print-type-size `{:#?}` adt general variants def {}",
                        layout.ty, adt_def.variants.len());
                 let variant_infos: Vec<_> =
@@ -1306,8 +1308,8 @@ impl<'a, 'tcx> LayoutCx<'tcx, TyCtxt<'a, 'tcx, 'tcx>> {
                                            layout.for_variant(self, i))
                     })
                     .collect();
-                record(adt_kind.into(), adt_packed, match layout.variants {
-                    Variants::Tagged { ref tag, .. } => Some(tag.value.size(self)),
+                record(adt_kind.into(), adt_packed, match discr_kind {
+                    DiscriminantKind::Tag => Some(discr.value.size(self)),
                     _ => None
                 }, variant_infos);
             }
@@ -1627,8 +1629,7 @@ impl<'a, 'tcx, C> TyLayoutMethods<'tcx, C> for Ty<'tcx>
                 })
             }
 
-            Variants::NicheFilling { ref variants, .. } |
-            Variants::Tagged { ref variants, .. } => {
+            Variants::Multiple { ref variants, .. } => {
                 &variants[variant_index]
             }
         };
@@ -1735,8 +1736,7 @@ impl<'a, 'tcx, C> TyLayoutMethods<'tcx, C> for Ty<'tcx>
                     }
 
                     // Discriminant field for enums (where applicable).
-                    Variants::Tagged { tag: ref discr, .. } |
-                    Variants::NicheFilling { niche: ref discr, .. } => {
+                    Variants::Multiple { ref discr, .. } => {
                         assert_eq!(i, 0);
                         let layout = LayoutDetails::scalar(cx, discr.clone());
                         return MaybeResult::from_ok(TyLayout {
@@ -1881,26 +1881,37 @@ impl<'a> HashStable<StableHashingContext<'a>> for Variants {
             Single { index } => {
                 index.hash_stable(hcx, hasher);
             }
-            Tagged {
-                ref tag,
+            Multiple {
+                ref discr,
+                ref discr_kind,
                 ref variants,
             } => {
-                tag.hash_stable(hcx, hasher);
+                discr.hash_stable(hcx, hasher);
+                discr_kind.hash_stable(hcx, hasher);
                 variants.hash_stable(hcx, hasher);
             }
-            NicheFilling {
+        }
+    }
+}
+
+impl<'a> HashStable<StableHashingContext<'a>> for DiscriminantKind {
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          hcx: &mut StableHashingContext<'a>,
+                                          hasher: &mut StableHasher<W>) {
+        use crate::ty::layout::DiscriminantKind::*;
+        mem::discriminant(self).hash_stable(hcx, hasher);
+
+        match *self {
+            Tag => {}
+            Niche {
                 dataful_variant,
                 ref niche_variants,
-                ref niche,
                 niche_start,
-                ref variants,
             } => {
                 dataful_variant.hash_stable(hcx, hasher);
                 niche_variants.start().hash_stable(hcx, hasher);
                 niche_variants.end().hash_stable(hcx, hasher);
-                niche.hash_stable(hcx, hasher);
                 niche_start.hash_stable(hcx, hasher);
-                variants.hash_stable(hcx, hasher);
             }
         }
     }

src/librustc/ty/query/on_disk_cache.rs

@@ -777,7 +777,6 @@ impl<'enc, 'a, 'tcx, E> CacheEncoder<'enc, 'a, 'tcx, E>
                                                  value: &V)
                                                  -> Result<(), E::Error>
     {
-        use crate::ty::codec::TyEncoder;
         let start_pos = self.position();
 
         tag.encode(self)?;

src/librustc/ty/structural_impls.rs

@@ -630,8 +630,8 @@ impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::Adjust<'a> {
                 Some(ty::adjustment::Adjust::ReifyFnPointer),
             ty::adjustment::Adjust::UnsafeFnPointer =>
                 Some(ty::adjustment::Adjust::UnsafeFnPointer),
-            ty::adjustment::Adjust::ClosureFnPointer =>
-                Some(ty::adjustment::Adjust::ClosureFnPointer),
+            ty::adjustment::Adjust::ClosureFnPointer(unsafety) =>
+                Some(ty::adjustment::Adjust::ClosureFnPointer(unsafety)),
             ty::adjustment::Adjust::MutToConstPointer =>
                 Some(ty::adjustment::Adjust::MutToConstPointer),
             ty::adjustment::Adjust::Unsize =>
@@ -1187,7 +1187,7 @@ EnumTypeFoldableImpl! {
         (ty::adjustment::Adjust::NeverToAny),
         (ty::adjustment::Adjust::ReifyFnPointer),
         (ty::adjustment::Adjust::UnsafeFnPointer),
-        (ty::adjustment::Adjust::ClosureFnPointer),
+        (ty::adjustment::Adjust::ClosureFnPointer)(a),
         (ty::adjustment::Adjust::MutToConstPointer),
         (ty::adjustment::Adjust::Unsize),
         (ty::adjustment::Adjust::Deref)(a),

src/librustc_codegen_llvm/attributes.rs

@@ -77,9 +77,15 @@ pub fn set_instrument_function(cx: &CodegenCx<'ll, '_>, llfn: &'ll Value) {
     if cx.sess().instrument_mcount() {
         // Similar to `clang -pg` behavior. Handled by the
         // `post-inline-ee-instrument` LLVM pass.
+
+        // The function name varies on platforms.
+        // See test/CodeGen/mcount.c in clang.
+        let mcount_name = CString::new(
+            cx.sess().target.target.options.target_mcount.as_str().as_bytes()).unwrap();
+
         llvm::AddFunctionAttrStringValue(
             llfn, llvm::AttributePlace::Function,
-            const_cstr!("instrument-function-entry-inlined"), const_cstr!("mcount"));
+            const_cstr!("instrument-function-entry-inlined"), &mcount_name);
     }
 }
 

src/librustc_codegen_llvm/context.rs

@@ -372,7 +372,6 @@ impl MiscMethods<'tcx> for CodegenCx<'ll, 'tcx> {
     // Returns a Value of the "eh_unwind_resume" lang item if one is defined,
     // otherwise declares it as an external function.
     fn eh_unwind_resume(&self) -> &'ll Value {
-        use crate::attributes;
         let unwresume = &self.eh_unwind_resume;
         if let Some(llfn) = unwresume.get() {
             return llfn;