Auto merge of rust-lang#68351 - Centril:rollup-0gzuh0p, r=Centril

Rollup of 5 pull requests

Successful merges:

 - rust-lang#67712 (Stabilize `#![feature(slice_patterns)]` in 1.42.0)
 - rust-lang#68224 (Prevent urls in headings)
 - rust-lang#68340 (clean up e0200 explanation)
 - rust-lang#68341 (Fix syscalls tables in docs of std::time.)
 - rust-lang#68342 (improve type_name_of_val docs)

Failed merges:

r? @ghost

Author: bors

src/doc/unstable-book/src/language-features/slice-patterns.md

@@ -476,11 +476,15 @@ pub const fn type_name<T: ?Sized>() -> &'static str {
 ///
 /// This is intended for diagnostic use. The exact contents and format of the
 /// string are not specified, other than being a best-effort description of the
-/// type. For example, `type_name_of::<Option<String>>(None)` could return
+/// type. For example, `type_name_of_val::<Option<String>>(None)` could return
 /// `"Option<String>"` or `"std::option::Option<std::string::String>"`, but not
 /// `"foobar"`. In addition, the output may change between versions of the
 /// compiler.
 ///
+/// This function does not resolve trait objects,
+/// meaning that `type_name_of_val(&7u32 as &dyn Debug)`
+/// may return `"dyn Debug"`, but not `"u32"`.
+///
 /// The type name should not be considered a unique identifier of a type;
 /// multiple types may share the same type name.
 ///

src/libcore/any.rs

@@ -133,7 +133,7 @@
 #![feature(associated_type_bounds)]
 #![feature(const_type_id)]
 #![feature(const_caller_location)]
-#![feature(slice_patterns)]
+#![cfg_attr(bootstrap, feature(slice_patterns))]
 
 #[prelude_import]
 #[allow(unused)]

src/libcore/lib.rs

@@ -19,7 +19,7 @@
 #![feature(range_is_empty)]
 #![feature(raw)]
 #![feature(saturating_neg)]
-#![feature(slice_patterns)]
+#![cfg_attr(bootstrap, feature(slice_patterns))]
 #![feature(sort_internals)]
 #![feature(slice_partition_at_index)]
 #![feature(specialization)]

src/libcore/tests/lib.rs

@@ -1,4 +1,4 @@
-#![feature(slice_patterns)]
+#![cfg_attr(bootstrap, feature(slice_patterns))]
 #![feature(test)]
 
 extern crate test;

src/librustc/benches/lib.rs

@@ -42,7 +42,7 @@
 #![feature(optin_builtin_traits)]
 #![feature(option_expect_none)]
 #![feature(range_is_empty)]
-#![feature(slice_patterns)]
+#![cfg_attr(bootstrap, feature(slice_patterns))]
 #![feature(specialization)]
 #![feature(unboxed_closures)]
 #![feature(thread_local)]

src/librustc/lib.rs

@@ -470,29 +470,8 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
         visit::walk_expr(self, e)
     }
 
-    fn visit_arm(&mut self, arm: &'a ast::Arm) {
-        visit::walk_arm(self, arm)
-    }
-
     fn visit_pat(&mut self, pattern: &'a ast::Pat) {
         match &pattern.kind {
-            PatKind::Slice(pats) => {
-                for pat in &*pats {
-                    let span = pat.span;
-                    let inner_pat = match &pat.kind {
-                        PatKind::Ident(.., Some(pat)) => pat,
-                        _ => pat,
-                    };
-                    if inner_pat.is_rest() {
-                        gate_feature_post!(
-                            &self,
-                            slice_patterns,
-                            span,
-                            "subslice patterns are unstable"
-                        );
-                    }
-                }
-            }
             PatKind::Box(..) => {
                 gate_feature_post!(
                     &self,

src/librustc_ast_passes/feature_gate.rs

@@ -2,7 +2,7 @@
 //! parsed by `rustc_parse` and then lowered, after the passes in this crate,
 //! by `rustc_ast_lowering`.
 
-#![feature(slice_patterns)]
+#![cfg_attr(bootstrap, feature(slice_patterns))]
 
 pub mod ast_validation;
 pub mod feature_gate;

src/librustc_ast_passes/lib.rs

@@ -4,7 +4,7 @@
 #![feature(box_syntax)]
 #![feature(core_intrinsics)]
 #![feature(libc)]
-#![feature(slice_patterns)]
+#![cfg_attr(bootstrap, feature(slice_patterns))]
 #![feature(stmt_expr_attributes)]
 #![feature(try_blocks)]
 #![feature(in_band_lifetimes)]

src/librustc_codegen_ssa/lib.rs

@@ -1,14 +1,23 @@
+An unsafe trait was implemented without an unsafe implementation.
+
+Erroneous code example:
+
+```compile_fail,E0200
+struct Foo;
+
+unsafe trait Bar { }
+
+impl Bar for Foo { } // error!
+```
+
 Unsafe traits must have unsafe implementations. This error occurs when an
 implementation for an unsafe trait isn't marked as unsafe. This may be resolved
 by marking the unsafe implementation as unsafe.
 
-```compile_fail,E0200
+```
 struct Foo;
 
 unsafe trait Bar { }
 
-// this won't compile because Bar is unsafe and impl isn't unsafe
-impl Bar for Foo { }
-// this will compile
-unsafe impl Bar for Foo { }
+unsafe impl Bar for Foo { } // ok!
 ```