Auto merge of #54215 - kennytm:rollup, r=kennytm

Rollup of 8 pull requests

Successful merges:

 - #53218 (Add a implementation of `From` for converting `&'a Option<T>` into `Option<&'a T>`)
 - #54024 (Fix compiling some rustc crates to wasm)
 - #54095 (Rename all mentions of `nil` to `unit`)
 - #54173 (Suggest valid crate type if invalid crate type is found)
 - #54194 (Remove println!() statement from HashMap unit test)
 - #54203 (Fix the stable release of os_str_str_ref_eq)
 - #54207 (re-mark the never docs as unstable)
 - #54210 (Update Cargo)

Failed merges:

r? @ghost

Author: bors

src/libcore/option.rs

@@ -1062,6 +1062,20 @@ impl<T> From<T> for Option<T> {
     }
 }
 
+#[stable(feature = "option_ref_from_ref_option", since = "1.30.0")]
+impl<'a, T> From<&'a Option<T>> for Option<&'a T> {
+    fn from(o: &'a Option<T>) -> Option<&'a T> {
+        o.as_ref()
+    }
+}
+
+#[stable(feature = "option_ref_from_ref_option", since = "1.30.0")]
+impl<'a, T> From<&'a mut Option<T>> for Option<&'a mut T> {
+    fn from(o: &'a mut Option<T>) -> Option<&'a mut T> {
+        o.as_mut()
+    }
+}
+
 /////////////////////////////////////////////////////////////////////////////
 // The Option Iterators
 /////////////////////////////////////////////////////////////////////////////

src/librustc/lint/builtin.rs

@@ -422,6 +422,7 @@ pub enum BuiltinLintDiagnostics {
     ProcMacroDeriveResolutionFallback(Span),
     MacroExpandedMacroExportsAccessedByAbsolutePaths(Span),
     ElidedLifetimesInPaths(usize, Span, bool, Span, String),
+    UnknownCrateTypes(Span, String, String),
 }
 
 impl BuiltinLintDiagnostics {
@@ -500,6 +501,14 @@ impl BuiltinLintDiagnostics {
                     Applicability::MachineApplicable
                 );
             }
+            BuiltinLintDiagnostics::UnknownCrateTypes(span, note, sugg) => {
+                db.span_suggestion_with_applicability(
+                    span,
+                    &note,
+                    sugg,
+                    Applicability::MaybeIncorrect
+                );
+            }
         }
     }
 }

src/librustc/traits/error_reporting.rs

@@ -661,7 +661,7 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
                         {
                             let predicate = trait_predicate.map_bound(|mut trait_pred| {
                                 trait_pred.trait_ref.substs = self.tcx.mk_substs_trait(
-                                    self.tcx.mk_nil(),
+                                    self.tcx.mk_unit(),
                                     &trait_pred.trait_ref.substs[1..],
                                 );
                                 trait_pred

src/librustc/ty/context.rs

@@ -2492,7 +2492,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
     }
 
     pub fn mk_nil_ptr(self) -> Ty<'tcx> {
-        self.mk_imm_ptr(self.mk_nil())
+        self.mk_imm_ptr(self.mk_unit())
     }
 
     pub fn mk_array(self, ty: Ty<'tcx>, n: u64) -> Ty<'tcx> {
@@ -2511,7 +2511,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
         iter.intern_with(|ts| self.mk_ty(Tuple(self.intern_type_list(ts))))
     }
 
-    pub fn mk_nil(self) -> Ty<'tcx> {
+    pub fn mk_unit(self) -> Ty<'tcx> {
         self.intern_tup(&[])
     }
 

src/librustc/ty/layout.rs

@@ -132,7 +132,7 @@ impl PrimitiveExt for Primitive {
             Int(i, signed) => i.to_ty(tcx, signed),
             Float(FloatTy::F32) => tcx.types.f32,
             Float(FloatTy::F64) => tcx.types.f64,
-            Pointer => tcx.mk_mut_ptr(tcx.mk_nil()),
+            Pointer => tcx.mk_mut_ptr(tcx.mk_unit()),
         }
     }
 }
@@ -1606,7 +1606,7 @@ impl<'a, 'tcx, C> TyLayoutMethods<'tcx, C> for Ty<'tcx>
                 // (which may have no non-DST form), and will work as long
                 // as the `Abi` or `FieldPlacement` is checked by users.
                 if i == 0 {
-                    let nil = tcx.mk_nil();
+                    let nil = tcx.mk_unit();
                     let ptr_ty = if this.ty.is_unsafe_ptr() {
                         tcx.mk_mut_ptr(nil)
                     } else {

src/librustc/ty/query/on_disk_cache.rs

@@ -1020,7 +1020,7 @@ impl<'enc, 'a, 'tcx, E> Encoder for CacheEncoder<'enc, 'a, 'tcx, E>
 {
     type Error = E::Error;
 
-    fn emit_nil(&mut self) -> Result<(), Self::Error> {
+    fn emit_unit(&mut self) -> Result<(), Self::Error> {
         Ok(())
     }
 

src/librustc/ty/sty.rs

@@ -1458,7 +1458,7 @@ impl RegionKind {
 
 /// Type utilities
 impl<'a, 'gcx, 'tcx> TyS<'tcx> {
-    pub fn is_nil(&self) -> bool {
+    pub fn is_unit(&self) -> bool {
         match self.sty {
             Tuple(ref tys) => tys.is_empty(),
             _ => false,

src/librustc/util/ppaux.rs

@@ -234,7 +234,7 @@ impl PrintContext {
             }
         }
         write!(f, ")")?;
-        if !output.is_nil() {
+        if !output.is_unit() {
             print!(f, self, write(" -> "), print_display(output))?;
         }
 

src/librustc_codegen_llvm/debuginfo/type_names.rs

@@ -160,7 +160,7 @@ pub fn push_debuginfo_type_name<'a, 'tcx>(cx: &CodegenCx<'a, 'tcx>,
 
             output.push(')');
 
-            if !sig.output().is_nil() {
+            if !sig.output().is_unit() {
                 output.push_str(" -> ");
                 push_debuginfo_type_name(cx, sig.output(), true, output);
             }

src/librustc_codegen_llvm/intrinsic.rs

@@ -968,7 +968,7 @@ fn get_rust_try_fn<'ll, 'tcx>(
     let i8p = tcx.mk_mut_ptr(tcx.types.i8);
     let fn_ty = tcx.mk_fn_ptr(ty::Binder::bind(tcx.mk_fn_sig(
         iter::once(i8p),
-        tcx.mk_nil(),
+        tcx.mk_unit(),
         false,
         hir::Unsafety::Unsafe,
         Abi::Rust