Auto merge of #68861 - Dylan-DPC:rollup-0m09hsg, r=Dylan-DPC

Rollup of 8 pull requests

Successful merges:

 - #68762 (Strip unnecessary subexpression)
 - #68790 (Improve `merge_from_succ`)
 - #68809 (Make more arithmetic functions unstably const)
 - #68832 (Clean up E0264, E0267 and E0268 explanations)
 - #68840 (On suggesting `#![recursion_limit = "X"]`, note current crate name)
 - #68846 (doc fix on doc attribute)
 - #68851 (Fix issue number of `capacity` method)
 - #68858 (Merge item id stable hashing functions)

Failed merges:

r? @ghost

Author: bors

src/doc/rustdoc/src/the-doc-attribute.md

@@ -39,7 +39,7 @@ crate level, and ones that are useful at the item level.
 
 ## At the crate level
 
-These options control how the docs look at a macro level.
+These options control how the docs look at a crate level.
 
 ### `html_favicon_url`
 

src/libcore/intrinsics.rs

@@ -1305,9 +1305,11 @@ extern "rust-intrinsic" {
 
     /// Performs an unchecked division, resulting in undefined behavior
     /// where y = 0 or x = `T::min_value()` and y = -1
+    #[rustc_const_unstable(feature = "const_int_unchecked_arith", issue = "none")]
     pub fn unchecked_div<T>(x: T, y: T) -> T;
     /// Returns the remainder of an unchecked division, resulting in
     /// undefined behavior where y = 0 or x = `T::min_value()` and y = -1
+    #[rustc_const_unstable(feature = "const_int_unchecked_arith", issue = "none")]
     pub fn unchecked_rem<T>(x: T, y: T) -> T;
 
     /// Performs an unchecked left shift, resulting in undefined behavior when
@@ -1321,14 +1323,17 @@ extern "rust-intrinsic" {
 
     /// Returns the result of an unchecked addition, resulting in
     /// undefined behavior when `x + y > T::max_value()` or `x + y < T::min_value()`.
+    #[rustc_const_unstable(feature = "const_int_unchecked_arith", issue = "none")]
     pub fn unchecked_add<T>(x: T, y: T) -> T;
 
     /// Returns the result of an unchecked subtraction, resulting in
     /// undefined behavior when `x - y > T::max_value()` or `x - y < T::min_value()`.
+    #[rustc_const_unstable(feature = "const_int_unchecked_arith", issue = "none")]
     pub fn unchecked_sub<T>(x: T, y: T) -> T;
 
     /// Returns the result of an unchecked multiplication, resulting in
     /// undefined behavior when `x * y > T::max_value()` or `x * y < T::min_value()`.
+    #[rustc_const_unstable(feature = "const_int_unchecked_arith", issue = "none")]
     pub fn unchecked_mul<T>(x: T, y: T) -> T;
 
     /// Performs rotate left.

src/libcore/lib.rs

@@ -72,6 +72,11 @@
 #![feature(concat_idents)]
 #![feature(const_alloc_layout)]
 #![feature(const_if_match)]
+#![feature(const_checked_int_methods)]
+#![feature(const_euclidean_int_methods)]
+#![feature(const_overflowing_int_methods)]
+#![feature(const_saturating_int_methods)]
+#![feature(const_int_unchecked_arith)]
 #![feature(const_panic)]
 #![feature(const_fn_union)]
 #![feature(const_generics)]

src/libcore/num/mod.rs

@@ -40,40 +40,14 @@ impl<'ctx> rustc_hir::HashStableContext for StableHashingContext<'ctx> {
         }
     }
 
-    // The following implementations of HashStable for `ItemId`, `TraitItemId`, and
-    // `ImplItemId` deserve special attention. Normally we do not hash `NodeId`s within
-    // the HIR, since they just signify a HIR nodes own path. But `ItemId` et al
-    // are used when another item in the HIR is *referenced* and we certainly
-    // want to pick up on a reference changing its target, so we hash the NodeIds
-    // in "DefPath Mode".
-
-    fn hash_item_id(&mut self, id: hir::ItemId, hasher: &mut StableHasher) {
+    fn hash_reference_to_item(&mut self, id: hir::HirId, hasher: &mut StableHasher) {
         let hcx = self;
-        let hir::ItemId { id } = id;
 
         hcx.with_node_id_hashing_mode(NodeIdHashingMode::HashDefPath, |hcx| {
             id.hash_stable(hcx, hasher);
         })
     }
 
-    fn hash_impl_item_id(&mut self, id: hir::ImplItemId, hasher: &mut StableHasher) {
-        let hcx = self;
-        let hir::ImplItemId { hir_id } = id;
-
-        hcx.with_node_id_hashing_mode(NodeIdHashingMode::HashDefPath, |hcx| {
-            hir_id.hash_stable(hcx, hasher);
-        })
-    }
-
-    fn hash_trait_item_id(&mut self, id: hir::TraitItemId, hasher: &mut StableHasher) {
-        let hcx = self;
-        let hir::TraitItemId { hir_id } = id;
-
-        hcx.with_node_id_hashing_mode(NodeIdHashingMode::HashDefPath, |hcx| {
-            hir_id.hash_stable(hcx, hasher);
-        })
-    }
-
     fn hash_hir_mod(&mut self, module: &hir::Mod<'_>, hasher: &mut StableHasher) {
         let hcx = self;
         let hir::Mod { inner: ref inner_span, ref item_ids } = *module;

src/librustc/ich/impls_hir.rs

@@ -1646,8 +1646,8 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
         let current_limit = self.tcx.sess.recursion_limit.get();
         let suggested_limit = current_limit * 2;
         err.help(&format!(
-            "consider adding a `#![recursion_limit=\"{}\"]` attribute to your crate",
-            suggested_limit
+            "consider adding a `#![recursion_limit=\"{}\"]` attribute to your crate (`{}`)",
+            suggested_limit, self.tcx.crate_name,
         ));
     }
 }

src/librustc/traits/error_reporting/suggestions.rs

@@ -1,4 +1,6 @@
-An unknown external lang item was used. Erroneous code example:
+An unknown external lang item was used.
+
+Erroneous code example:
 
 ```compile_fail,E0264
 #![feature(lang_items)]

src/librustc_error_codes/error_codes/E0264.md

@@ -1,5 +1,7 @@
-This error indicates the use of a loop keyword (`break` or `continue`) inside a
-closure but outside of any loop. Erroneous code example:
+A loop keyword (`break` or `continue`) was used inside a closure but outside of
+any loop.
+
+Erroneous code example:
 
 ```compile_fail,E0267
 let w = || { break; }; // error: `break` inside of a closure

src/librustc_error_codes/error_codes/E0267.md

@@ -1,13 +1,14 @@
-This error indicates the use of a loop keyword (`break` or `continue`) outside
-of a loop. Without a loop to break out of or continue in, no sensible action can
-be taken. Erroneous code example:
+A loop keyword (`break` or `continue`) was used outside of a loop.
+
+Erroneous code example:
 
 ```compile_fail,E0268
 fn some_func() {
     break; // error: `break` outside of a loop
 }
 ```
 
+Without a loop to break out of or continue in, no sensible action can be taken.
 Please verify that you are using `break` and `continue` only in loops. Example:
 
 ```

src/librustc_error_codes/error_codes/E0268.md

@@ -609,8 +609,8 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                 &format!("recursion limit reached while expanding `{}`", expn_data.kind.descr()),
             );
             err.help(&format!(
-                "consider adding a `#![recursion_limit=\"{}\"]` attribute to your crate",
-                suggested_limit
+                "consider adding a `#![recursion_limit=\"{}\"]` attribute to your crate (`{}`)",
+                suggested_limit, self.cx.ecfg.crate_name,
             ));
             err.emit();
             self.cx.trace_macros_diag();