Auto merge of #65733 - Centril:rollup-0zth66f, r=Centril

Rollup of 12 pull requests

Successful merges:

 - #64178 (More Clippy fixes for alloc, core and std)
 - #65144 (Add Cow::is_borrowed and Cow::is_owned)
 - #65193 (Lockless LintStore)
 - #65479 (Add the `matches!( $expr, $pat ) -> bool` macro)
 - #65518 (Avoid ICE when checking `Destination` of `break` inside a closure)
 - #65583 (rustc_metadata: use a table for super_predicates, fn_sig, impl_trait_ref.)
 - #65641 (Derive `Rustc{En,De}codable` for `TokenStream`.)
 - #65648 (Eliminate `intersect_opt`.)
 - #65657 (Remove `InternedString`)
 - #65691 (Update E0659 error code long explanation to 2018 edition)
 - #65696 (Fix an issue with const inference variables sticking around under Chalk + NLL)
 - #65704 (relax ExactSizeIterator bound on write_bytes)

Failed merges:

r? @ghost

Cargo.lock

@@ -3483,6 +3483,7 @@ dependencies = [
  "rustc_data_structures",
  "rustc_errors",
  "rustc_interface",
+ "rustc_lint",
  "rustc_metadata",
  "rustc_mir",
  "rustc_plugin",

src/liballoc/borrow.rs

@@ -207,6 +207,47 @@ impl<B: ?Sized + ToOwned> Clone for Cow<'_, B> {
 }
 
 impl<B: ?Sized + ToOwned> Cow<'_, B> {
+    /// Returns true if the data is borrowed, i.e. if `to_mut` would require additional work.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(cow_is_borrowed)]
+    /// use std::borrow::Cow;
+    ///
+    /// let cow = Cow::Borrowed("moo");
+    /// assert!(cow.is_borrowed());
+    ///
+    /// let bull: Cow<'_, str> = Cow::Owned("...moo?".to_string());
+    /// assert!(!bull.is_borrowed());
+    /// ```
+    #[unstable(feature = "cow_is_borrowed", issue = "65143")]
+    pub fn is_borrowed(&self) -> bool {
+        match *self {
+            Borrowed(_) => true,
+            Owned(_) => false,
+        }
+    }
+
+    /// Returns true if the data is owned, i.e. if `to_mut` would be a no-op.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(cow_is_borrowed)]
+    /// use std::borrow::Cow;
+    ///
+    /// let cow: Cow<'_, str> = Cow::Owned("moo".to_string());
+    /// assert!(cow.is_owned());
+    ///
+    /// let bull = Cow::Borrowed("...moo?");
+    /// assert!(!bull.is_owned());
+    /// ```
+    #[unstable(feature = "cow_is_borrowed", issue = "65143")]
+    pub fn is_owned(&self) -> bool {
+        !self.is_borrowed()
+    }
+
     /// Acquires a mutable reference to the owned form of the data.
     ///
     /// Clones the data if it is not already owned.

src/liballoc/collections/vec_deque.rs

@@ -1817,7 +1817,7 @@ impl<T> VecDeque<T> {
             }
         }
 
-        return elem;
+        elem
     }
 
     /// Splits the `VecDeque` into two at the given index.

src/liballoc/lib.rs

@@ -85,6 +85,7 @@
 #![feature(const_generic_impls_guard)]
 #![feature(const_generics)]
 #![feature(const_in_array_repeat_expressions)]
+#![feature(cow_is_borrowed)]
 #![feature(dispatch_from_dyn)]
 #![feature(core_intrinsics)]
 #![feature(container_error_extra)]

src/liballoc/str.rs

@@ -456,7 +456,7 @@ impl str {
                 }
             }
         }
-        return s;
+        s
     }
 
     /// Converts a [`Box<str>`] into a [`String`] without copying or allocating.

src/liballoc/sync.rs

@@ -1638,7 +1638,7 @@ impl<T: ?Sized> Clone for Weak<T> {
             }
         }
 
-        return Weak { ptr: self.ptr };
+        Weak { ptr: self.ptr }
     }
 }
 

src/libcore/fmt/mod.rs

@@ -2025,7 +2025,7 @@ impl<T: ?Sized> Pointer for *const T {
         if f.alternate() {
             f.flags |= 1 << (FlagV1::SignAwareZeroPad as u32);
 
-            if let None = f.width {
+            if f.width.is_none() {
                 f.width = Some(((mem::size_of::<usize>() * 8) / 4) + 2);
             }
         }

src/libcore/macros.rs

@@ -238,6 +238,33 @@ macro_rules! debug_assert_ne {
     ($($arg:tt)*) => (if $crate::cfg!(debug_assertions) { $crate::assert_ne!($($arg)*); })
 }
 
+/// Returns whether the given expression matches any of the given patterns.
+///
+/// Like in a `match` expression, the pattern can be optionally followed by `if`
+/// and a guard expression that has access to names bound by the pattern.
+///
+/// # Examples
+///
+/// ```
+/// #![feature(matches_macro)]
+///
+/// let foo = 'f';
+/// assert!(matches!(foo, 'A'..='Z' | 'a'..='z'));
+///
+/// let bar = Some(4);
+/// assert!(matches!(bar, Some(x) if x > 2));
+/// ```
+#[macro_export]
+#[unstable(feature = "matches_macro", issue = "65721")]
+macro_rules! matches {
+    ($expression:expr, $( $pattern:pat )|+ $( if $guard: expr )?) => {
+        match $expression {
+            $( $pattern )|+ $( if $guard )? => true,
+            _ => false
+        }
+    }
+}
+
 /// Unwraps a result or propagates its error.
 ///
 /// The `?` operator was added to replace `try!` and should be used instead.

src/libcore/num/dec2flt/algorithm.rs

@@ -143,13 +143,12 @@ pub fn fast_path<T: RawFloat>(integral: &[u8], fractional: &[u8], e: i64) -> Opt
 /// > not a bound for the true error, but bounds the difference between the approximation z and
 /// > the best possible approximation that uses p bits of significand.)
 pub fn bellerophon<T: RawFloat>(f: &Big, e: i16) -> T {
-    let slop;
-    if f <= &Big::from_u64(T::MAX_SIG) {
+    let slop = if f <= &Big::from_u64(T::MAX_SIG) {
         // The cases abs(e) < log5(2^N) are in fast_path()
-        slop = if e >= 0 { 0 } else { 3 };
+        if e >= 0 { 0 } else { 3 }
     } else {
-        slop = if e >= 0 { 1 } else { 4 };
-    }
+        if e >= 0 { 1 } else { 4 }
+    };
     let z = rawfp::big_to_fp(f).mul(&power_of_ten(e)).normalize();
     let exp_p_n = 1 << (P - T::SIG_BITS as u32);
     let lowbits: i64 = (z.f % exp_p_n) as i64;

src/libcore/option.rs

@@ -837,9 +837,8 @@ impl<T> Option<T> {
     #[inline]
     #[stable(feature = "option_entry", since = "1.20.0")]
     pub fn get_or_insert_with<F: FnOnce() -> T>(&mut self, f: F) -> &mut T {
-        match *self {
-            None => *self = Some(f()),
-            _ => (),
+        if let None = *self {
+            *self = Some(f());
         }
 
         match *self {

src/libpanic_unwind/gcc.rs

@@ -156,21 +156,21 @@ unsafe extern "C" fn rust_eh_personality(version: c_int,
     if actions as i32 & uw::_UA_SEARCH_PHASE as i32 != 0 {
         match eh_action {
             EHAction::None |
-            EHAction::Cleanup(_) => return uw::_URC_CONTINUE_UNWIND,
-            EHAction::Catch(_) => return uw::_URC_HANDLER_FOUND,
-            EHAction::Terminate => return uw::_URC_FATAL_PHASE1_ERROR,
+            EHAction::Cleanup(_) => uw::_URC_CONTINUE_UNWIND,
+            EHAction::Catch(_) => uw::_URC_HANDLER_FOUND,
+            EHAction::Terminate => uw::_URC_FATAL_PHASE1_ERROR,
         }
     } else {
         match eh_action {
-            EHAction::None => return uw::_URC_CONTINUE_UNWIND,
+            EHAction::None => uw::_URC_CONTINUE_UNWIND,
             EHAction::Cleanup(lpad) |
             EHAction::Catch(lpad) => {
                 uw::_Unwind_SetGR(context, UNWIND_DATA_REG.0, exception_object as uintptr_t);
                 uw::_Unwind_SetGR(context, UNWIND_DATA_REG.1, 0);
                 uw::_Unwind_SetIP(context, lpad);
-                return uw::_URC_INSTALL_CONTEXT;
+                uw::_URC_INSTALL_CONTEXT
             }
-            EHAction::Terminate => return uw::_URC_FATAL_PHASE2_ERROR,
+            EHAction::Terminate => uw::_URC_FATAL_PHASE2_ERROR,
         }
     }
 }

src/libpanic_unwind/seh64_gnu.rs

@@ -46,7 +46,7 @@ pub fn payload() -> *mut u8 {
 
 pub unsafe fn cleanup(ptr: *mut u8) -> Box<dyn Any + Send> {
     let panic_ctx = Box::from_raw(ptr as *mut PanicData);
-    return panic_ctx.data;
+    panic_ctx.data
 }
 
 // SEH doesn't support resuming unwinds after calling a landing pad like

src/librustc/dep_graph/dep_node.rs

@@ -59,7 +59,7 @@ use crate::ich::{Fingerprint, StableHashingContext};
 use rustc_data_structures::stable_hasher::{StableHasher, HashStable};
 use std::fmt;
 use std::hash::Hash;
-use syntax_pos::symbol::InternedString;
+use syntax_pos::symbol::Symbol;
 use crate::traits;
 use crate::traits::query::{
     CanonicalProjectionGoal, CanonicalTyGoal, CanonicalTypeOpAscribeUserTypeGoal,
@@ -426,7 +426,7 @@ rustc_dep_node_append!([define_dep_nodes!][ <'tcx>
 
     [anon] TraitSelect,
 
-    [] CompileCodegenUnit(InternedString),
+    [] CompileCodegenUnit(Symbol),
 
     [eval_always] Analysis(CrateNum),
 ]);

src/librustc/hir/lowering.rs

@@ -792,15 +792,15 @@ impl<'a> LoweringContext<'a> {
         // really show up for end-user.
         let (str_name, kind) = match hir_name {
             ParamName::Plain(ident) => (
-                ident.as_interned_str(),
+                ident.name,
                 hir::LifetimeParamKind::InBand,
             ),
             ParamName::Fresh(_) => (
-                kw::UnderscoreLifetime.as_interned_str(),
+                kw::UnderscoreLifetime,
                 hir::LifetimeParamKind::Elided,
             ),
             ParamName::Error => (
-                kw::UnderscoreLifetime.as_interned_str(),
+                kw::UnderscoreLifetime,
                 hir::LifetimeParamKind::Error,
             ),
         };
@@ -1590,7 +1590,7 @@ impl<'a> LoweringContext<'a> {
                     self.context.resolver.definitions().create_def_with_parent(
                         self.parent,
                         def_node_id,
-                        DefPathData::LifetimeNs(name.ident().as_interned_str()),
+                        DefPathData::LifetimeNs(name.ident().name),
                         ExpnId::root(),
                         lifetime.span);
 

src/librustc/hir/map/collector.rs

@@ -186,13 +186,13 @@ impl<'a, 'hir> NodeCollector<'a, 'hir> {
             });
 
         let mut upstream_crates: Vec<_> = cstore.crates_untracked().iter().map(|&cnum| {
-            let name = cstore.crate_name_untracked(cnum).as_interned_str();
+            let name = cstore.crate_name_untracked(cnum);
             let disambiguator = cstore.crate_disambiguator_untracked(cnum).to_fingerprint();
             let hash = cstore.crate_hash_untracked(cnum);
             (name, disambiguator, hash)
         }).collect();
 
-        upstream_crates.sort_unstable_by_key(|&(name, dis, _)| (name, dis));
+        upstream_crates.sort_unstable_by_key(|&(name, dis, _)| (name.as_str(), dis));
 
         // We hash the final, remapped names of all local source files so we
         // don't have to include the path prefix remapping commandline args.

src/librustc/hir/map/def_collector.rs

@@ -57,7 +57,7 @@ impl<'a> DefCollector<'a> {
 
         // For async functions, we need to create their inner defs inside of a
         // closure to match their desugared representation.
-        let fn_def_data = DefPathData::ValueNs(name.as_interned_str());
+        let fn_def_data = DefPathData::ValueNs(name);
         let fn_def = self.create_def(id, fn_def_data, span);
         return self.with_parent(fn_def, |this| {
             this.create_def(return_impl_trait_id, DefPathData::ImplTrait, span);
@@ -83,8 +83,7 @@ impl<'a> DefCollector<'a> {
                 .unwrap_or_else(|| {
                     let node_id = NodeId::placeholder_from_expn_id(self.expansion);
                     sym::integer(self.definitions.placeholder_field_indices[&node_id])
-                })
-                .as_interned_str();
+                });
             let def = self.create_def(field.id, DefPathData::ValueNs(name), field.span);
             self.with_parent(def, |this| visit::walk_struct_field(this, field));
         }
@@ -109,7 +108,7 @@ impl<'a> visit::Visitor<'a> for DefCollector<'a> {
             ItemKind::Mod(..) | ItemKind::Trait(..) | ItemKind::TraitAlias(..) |
             ItemKind::Enum(..) | ItemKind::Struct(..) | ItemKind::Union(..) |
             ItemKind::OpaqueTy(..) | ItemKind::ExternCrate(..) | ItemKind::ForeignMod(..) |
-            ItemKind::TyAlias(..) => DefPathData::TypeNs(i.ident.as_interned_str()),
+            ItemKind::TyAlias(..) => DefPathData::TypeNs(i.ident.name),
             ItemKind::Fn(
                 ref decl,
                 ref header,
@@ -127,8 +126,8 @@ impl<'a> visit::Visitor<'a> for DefCollector<'a> {
                 )
             }
             ItemKind::Static(..) | ItemKind::Const(..) | ItemKind::Fn(..) =>
-                DefPathData::ValueNs(i.ident.as_interned_str()),
-            ItemKind::MacroDef(..) => DefPathData::MacroNs(i.ident.as_interned_str()),
+                DefPathData::ValueNs(i.ident.name),
+            ItemKind::MacroDef(..) => DefPathData::MacroNs(i.ident.name),
             ItemKind::Mac(..) => return self.visit_macro_invoc(i.id),
             ItemKind::GlobalAsm(..) => DefPathData::Misc,
             ItemKind::Use(..) => {
@@ -162,7 +161,7 @@ impl<'a> visit::Visitor<'a> for DefCollector<'a> {
         }
 
         let def = self.create_def(foreign_item.id,
-                                  DefPathData::ValueNs(foreign_item.ident.as_interned_str()),
+                                  DefPathData::ValueNs(foreign_item.ident.name),
                                   foreign_item.span);
 
         self.with_parent(def, |this| {
@@ -175,7 +174,7 @@ impl<'a> visit::Visitor<'a> for DefCollector<'a> {
             return self.visit_macro_invoc(v.id);
         }
         let def = self.create_def(v.id,
-                                  DefPathData::TypeNs(v.ident.as_interned_str()),
+                                  DefPathData::TypeNs(v.ident.name),
                                   v.span);
         self.with_parent(def, |this| {
             if let Some(ctor_hir_id) = v.data.ctor_id() {
@@ -202,7 +201,7 @@ impl<'a> visit::Visitor<'a> for DefCollector<'a> {
             self.visit_macro_invoc(param.id);
             return;
         }
-        let name = param.ident.as_interned_str();
+        let name = param.ident.name;
         let def_path_data = match param.kind {
             GenericParamKind::Lifetime { .. } => DefPathData::LifetimeNs(name),
             GenericParamKind::Type { .. } => DefPathData::TypeNs(name),
@@ -216,9 +215,9 @@ impl<'a> visit::Visitor<'a> for DefCollector<'a> {
     fn visit_trait_item(&mut self, ti: &'a TraitItem) {
         let def_data = match ti.kind {
             TraitItemKind::Method(..) | TraitItemKind::Const(..) =>
-                DefPathData::ValueNs(ti.ident.as_interned_str()),
+                DefPathData::ValueNs(ti.ident.name),
             TraitItemKind::Type(..) => {
-                DefPathData::TypeNs(ti.ident.as_interned_str())
+                DefPathData::TypeNs(ti.ident.name)
             },
             TraitItemKind::Macro(..) => return self.visit_macro_invoc(ti.id),
         };
@@ -243,12 +242,10 @@ impl<'a> visit::Visitor<'a> for DefCollector<'a> {
                     body,
                 )
             }
-            ImplItemKind::Method(..) | ImplItemKind::Const(..) =>
-                DefPathData::ValueNs(ii.ident.as_interned_str()),
+            ImplItemKind::Method(..) |
+            ImplItemKind::Const(..) => DefPathData::ValueNs(ii.ident.name),
             ImplItemKind::TyAlias(..) |
-            ImplItemKind::OpaqueTy(..) => {
-                DefPathData::TypeNs(ii.ident.as_interned_str())
-            },
+            ImplItemKind::OpaqueTy(..) => DefPathData::TypeNs(ii.ident.name),
             ImplItemKind::Macro(..) => return self.visit_macro_invoc(ii.id),
         };