Auto merge of #60612 - Centril:rollup-61drhqt, r=Centril

Rollup of 5 pull requests

Successful merges:

 - #60489 (Remove hamburger button from source code page)
 - #60535 (Correct handling of arguments in async fn)
 - #60579 (Rename `ParamTy::idx` to `ParamTy::index`)
 - #60583 (Fix parsing issue with negative literals as const generic arguments)
 - #60609 (Be a bit more explicit asserting over the vec rather than the len)

Failed merges:

r? @ghost

24 files changed, 375 insertions, 62 deletions

diff --git a/src/libcore/mem.rs b/src/libcore/mem.rs
index 5bd442bc066..9fb071d2952 100644
--- a/src/libcore/mem.rs
+++ b/src/libcore/mem.rs
@@ -665,8 +665,8 @@ pub fn swap<T>(x: &mut T, y: &mut T) {
 /// let mut v: Vec<i32> = vec![1, 2];
 ///
 /// let old_v = mem::replace(&mut v, vec![3, 4, 5]);
-/// assert_eq!(2, old_v.len());
-/// assert_eq!(3, v.len());
+/// assert_eq!(vec![1, 2], old_v);
+/// assert_eq!(vec![3, 4, 5], v);
 /// ```
 ///
 /// `replace` allows consumption of a struct field by replacing it with another value.
diff --git a/src/librustc/traits/error_reporting.rs b/src/librustc/traits/error_reporting.rs
index 007ff32f327..d9ccbba69d5 100644
--- a/src/librustc/traits/error_reporting.rs
+++ b/src/librustc/traits/error_reporting.rs
@@ -1453,7 +1453,7 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
             fn tcx<'b>(&'b self) -> TyCtxt<'b, 'gcx, 'tcx> { self.infcx.tcx }
 
             fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> {
-                if let ty::Param(ty::ParamTy {name, ..}) = ty.sty {
+                if let ty::Param(ty::ParamTy {name, .. }) = ty.sty {
                     let infcx = self.infcx;
                     self.var_map.entry(ty).or_insert_with(||
                         infcx.next_ty_var(
diff --git a/src/librustc/traits/select.rs b/src/librustc/traits/select.rs
index f0c402789c4..d68e2be9ea0 100644
--- a/src/librustc/traits/select.rs
+++ b/src/librustc/traits/select.rs
@@ -3424,7 +3424,7 @@ impl<'cx, 'gcx, 'tcx> SelectionContext<'cx, 'gcx, 'tcx> {
                 let mut found = false;
                 for ty in field.walk() {
                     if let ty::Param(p) = ty.sty {
-                        ty_params.insert(p.idx as usize);
+                        ty_params.insert(p.index as usize);
                         found = true;
                     }
                 }
diff --git a/src/librustc/traits/util.rs b/src/librustc/traits/util.rs
index 90f62a4d132..be29ea5701b 100644
--- a/src/librustc/traits/util.rs
+++ b/src/librustc/traits/util.rs
@@ -204,7 +204,7 @@ impl<'cx, 'gcx, 'tcx> Elaborator<'cx, 'gcx, 'tcx> {
                            },
 
                            Component::Param(p) => {
-                               let ty = tcx.mk_ty_param(p.idx, p.name);
+                               let ty = tcx.mk_ty_param(p.index, p.name);
                                Some(ty::Predicate::TypeOutlives(
                                    ty::Binder::dummy(ty::OutlivesPredicate(ty, r_min))))
                            },
diff --git a/src/librustc/ty/context.rs b/src/librustc/ty/context.rs
index 19440d0bc64..15524ca6e93 100644
--- a/src/librustc/ty/context.rs
+++ b/src/librustc/ty/context.rs
@@ -2715,10 +2715,8 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
     }
 
     #[inline]
-    pub fn mk_ty_param(self,
-                       index: u32,
-                       name: InternedString) -> Ty<'tcx> {
-        self.mk_ty(Param(ParamTy { idx: index, name: name }))
+    pub fn mk_ty_param(self, index: u32, name: InternedString) -> Ty<'tcx> {
+        self.mk_ty(Param(ParamTy { index, name: name }))
     }
 
     #[inline]
diff --git a/src/librustc/ty/mod.rs b/src/librustc/ty/mod.rs
index cb92e4b7470..7b749957c3f 100644
--- a/src/librustc/ty/mod.rs
+++ b/src/librustc/ty/mod.rs
@@ -979,7 +979,7 @@ impl<'a, 'gcx, 'tcx> Generics {
                       param: &ParamTy,
                       tcx: TyCtxt<'a, 'gcx, 'tcx>)
                       -> &'tcx GenericParamDef {
-        if let Some(index) = param.idx.checked_sub(self.parent_count as u32) {
+        if let Some(index) = param.index.checked_sub(self.parent_count as u32) {
             let param = &self.params[index as usize];
             match param.kind {
                 GenericParamDefKind::Type { .. } => param,
diff --git a/src/librustc/ty/relate.rs b/src/librustc/ty/relate.rs
index d7b19070741..20493413274 100644
--- a/src/librustc/ty/relate.rs
+++ b/src/librustc/ty/relate.rs
@@ -390,7 +390,7 @@ pub fn super_relate_tys<'a, 'gcx, 'tcx, R>(relation: &mut R,
         }
 
         (&ty::Param(ref a_p), &ty::Param(ref b_p))
-            if a_p.idx == b_p.idx =>
+            if a_p.index == b_p.index =>
         {
             Ok(a)
         }
diff --git a/src/librustc/ty/structural_impls.rs b/src/librustc/ty/structural_impls.rs
index f81394a878f..cf04d6eac3a 100644
--- a/src/librustc/ty/structural_impls.rs
+++ b/src/librustc/ty/structural_impls.rs
@@ -240,7 +240,7 @@ impl fmt::Debug for Ty<'tcx> {
 
 impl fmt::Debug for ty::ParamTy {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "{}/#{}", self.name, self.idx)
+        write!(f, "{}/#{}", self.name, self.index)
     }
 }
 
diff --git a/src/librustc/ty/sty.rs b/src/librustc/ty/sty.rs
index cca40c379fc..760f3d60d05 100644
--- a/src/librustc/ty/sty.rs
+++ b/src/librustc/ty/sty.rs
@@ -1111,13 +1111,13 @@ pub type CanonicalPolyFnSig<'tcx> = Canonical<'tcx, Binder<FnSig<'tcx>>>;
 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord,
          Hash, RustcEncodable, RustcDecodable, HashStable)]
 pub struct ParamTy {
-    pub idx: u32,
+    pub index: u32,
     pub name: InternedString,
 }
 
 impl<'a, 'gcx, 'tcx> ParamTy {
     pub fn new(index: u32, name: InternedString) -> ParamTy {
-        ParamTy { idx: index, name: name }
+        ParamTy { index, name: name }
     }
 
     pub fn for_self() -> ParamTy {
@@ -1129,14 +1129,14 @@ impl<'a, 'gcx, 'tcx> ParamTy {
     }
 
     pub fn to_ty(self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Ty<'tcx> {
-        tcx.mk_ty_param(self.idx, self.name)
+        tcx.mk_ty_param(self.index, self.name)
     }
 
     pub fn is_self(&self) -> bool {
-        // FIXME(#50125): Ignoring `Self` with `idx != 0` might lead to weird behavior elsewhere,
+        // FIXME(#50125): Ignoring `Self` with `index != 0` might lead to weird behavior elsewhere,
         // but this should only be possible when using `-Z continue-parse-after-error` like
         // `compile-fail/issue-36638.rs`.
-        self.name == keywords::SelfUpper.name().as_str() && self.idx == 0
+        self.name == keywords::SelfUpper.name().as_str() && self.index == 0
     }
 }
 
@@ -1763,7 +1763,7 @@ impl<'a, 'gcx, 'tcx> TyS<'tcx> {
 
     pub fn is_param(&self, index: u32) -> bool {
         match self.sty {
-            ty::Param(ref data) => data.idx == index,
+            ty::Param(ref data) => data.index == index,
             _ => false,
         }
     }
diff --git a/src/librustc/ty/subst.rs b/src/librustc/ty/subst.rs
index e5bd3f15efe..72dfe581ba7 100644
--- a/src/librustc/ty/subst.rs
+++ b/src/librustc/ty/subst.rs
@@ -547,7 +547,7 @@ impl<'a, 'gcx, 'tcx> TypeFolder<'gcx, 'tcx> for SubstFolder<'a, 'gcx, 'tcx> {
 impl<'a, 'gcx, 'tcx> SubstFolder<'a, 'gcx, 'tcx> {
     fn ty_for_param(&self, p: ty::ParamTy, source_ty: Ty<'tcx>) -> Ty<'tcx> {
         // Look up the type in the substitutions. It really should be in there.
-        let opt_ty = self.substs.get(p.idx as usize).map(|k| k.unpack());
+        let opt_ty = self.substs.get(p.index as usize).map(|k| k.unpack());
         let ty = match opt_ty {
             Some(UnpackedKind::Type(ty)) => ty,
             Some(kind) => {
@@ -558,7 +558,7 @@ impl<'a, 'gcx, 'tcx> SubstFolder<'a, 'gcx, 'tcx> {
                      when substituting (root type={:?}) substs={:?}",
                     p,
                     source_ty,
-                    p.idx,
+                    p.index,
                     kind,
                     self.root_ty,
                     self.substs,
@@ -572,7 +572,7 @@ impl<'a, 'gcx, 'tcx> SubstFolder<'a, 'gcx, 'tcx> {
                      when substituting (root type={:?}) substs={:?}",
                     p,
                     source_ty,
-                    p.idx,
+                    p.index,
                     self.root_ty,
                     self.substs,
                 );
diff --git a/src/librustc_typeck/check/method/probe.rs b/src/librustc_typeck/check/method/probe.rs
index 314f7e97cd2..251400e65f3 100644
--- a/src/librustc_typeck/check/method/probe.rs
+++ b/src/librustc_typeck/check/method/probe.rs
@@ -757,8 +757,7 @@ impl<'a, 'gcx, 'tcx> ProbeContext<'a, 'gcx, 'tcx> {
         });
     }
 
-    fn assemble_inherent_candidates_from_param(&mut self,
-                                               param_ty: ty::ParamTy) {
+    fn assemble_inherent_candidates_from_param(&mut self, param_ty: ty::ParamTy) {
         // FIXME -- Do we want to commit to this behavior for param bounds?
 
         let bounds = self.param_env
diff --git a/src/librustc_typeck/check/mod.rs b/src/librustc_typeck/check/mod.rs
index 82fcf8ff52f..64c8ff8ff86 100644
--- a/src/librustc_typeck/check/mod.rs
+++ b/src/librustc_typeck/check/mod.rs
@@ -5793,9 +5793,9 @@ pub fn check_bounds_are_used<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
     let mut types_used = vec![false; own_counts.types];
 
     for leaf_ty in ty.walk() {
-        if let ty::Param(ty::ParamTy { idx, .. }) = leaf_ty.sty {
-            debug!("Found use of ty param num {}", idx);
-            types_used[idx as usize - own_counts.lifetimes] = true;
+        if let ty::Param(ty::ParamTy { index, .. }) = leaf_ty.sty {
+            debug!("Found use of ty param num {}", index);
+            types_used[index as usize - own_counts.lifetimes] = true;
         } else if let ty::Error = leaf_ty.sty {
             // If there is already another error, do not emit
             // an error for not using a type Parameter.
diff --git a/src/librustc_typeck/check/wfcheck.rs b/src/librustc_typeck/check/wfcheck.rs
index 1420c66c73e..fd7d6fe694c 100644
--- a/src/librustc_typeck/check/wfcheck.rs
+++ b/src/librustc_typeck/check/wfcheck.rs
@@ -494,7 +494,7 @@ fn check_where_clauses<'a, 'gcx, 'fcx, 'tcx>(
         impl<'tcx> ty::fold::TypeVisitor<'tcx> for CountParams {
             fn visit_ty(&mut self, t: Ty<'tcx>) -> bool {
                 if let ty::Param(param) = t.sty {
-                    self.params.insert(param.idx);
+                    self.params.insert(param.index);
                 }
                 t.super_visit_with(self)
             }
diff --git a/src/librustc_typeck/constrained_generic_params.rs b/src/librustc_typeck/constrained_generic_params.rs
index 18bf66ceb35..49910e39fed 100644
--- a/src/librustc_typeck/constrained_generic_params.rs
+++ b/src/librustc_typeck/constrained_generic_params.rs
@@ -8,7 +8,7 @@ use syntax::source_map::Span;
 pub struct Parameter(pub u32);
 
 impl From<ty::ParamTy> for Parameter {
-    fn from(param: ty::ParamTy) -> Self { Parameter(param.idx) }
+    fn from(param: ty::ParamTy) -> Self { Parameter(param.index) }
 }
 
 impl From<ty::EarlyBoundRegion> for Parameter {
diff --git a/src/librustc_typeck/variance/constraints.rs b/src/librustc_typeck/variance/constraints.rs
index 5079a3bb55f..4f82978f01a 100644
--- a/src/librustc_typeck/variance/constraints.rs
+++ b/src/librustc_typeck/variance/constraints.rs
@@ -324,7 +324,7 @@ impl<'a, 'tcx> ConstraintContext<'a, 'tcx> {
             }
 
             ty::Param(ref data) => {
-                self.add_constraint(current, data.idx, variance);
+                self.add_constraint(current, data.index, variance);
             }
 
             ty::FnPtr(sig) => {
diff --git a/src/librustdoc/html/static/rustdoc.css b/src/librustdoc/html/static/rustdoc.css
index 4204d20498d..880b8243355 100644
--- a/src/librustdoc/html/static/rustdoc.css
+++ b/src/librustdoc/html/static/rustdoc.css
@@ -1052,6 +1052,10 @@ h3 > .collapse-toggle, h4 > .collapse-toggle {
 		height: 45px;
 	}
 
+	.rustdoc.source > .sidebar > .sidebar-menu {
+		display: none;
+	}
+
 	.sidebar-elems {
 		position: fixed;
 		z-index: 1;
diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs
index 084091f4c2a..921b857bf98 100644
--- a/src/libsyntax/parse/parser.rs
+++ b/src/libsyntax/parse/parser.rs
@@ -1576,7 +1576,7 @@ impl<'a> Parser<'a> {
             let ident = self.parse_ident()?;
             let mut generics = self.parse_generics()?;
 
-            let d = self.parse_fn_decl_with_self(|p: &mut Parser<'a>| {
+            let mut decl = self.parse_fn_decl_with_self(|p: &mut Parser<'a>| {
                 // This is somewhat dubious; We don't want to allow
                 // argument names to be left off if there is a
                 // definition...
@@ -1585,7 +1585,7 @@ impl<'a> Parser<'a> {
                 p.parse_arg_general(p.span.rust_2018(), true, false)
             })?;
             generics.where_clause = self.parse_where_clause()?;
-            self.construct_async_arguments(&mut asyncness, &d);
+            self.construct_async_arguments(&mut asyncness, &mut decl);
 
             let sig = ast::MethodSig {
                 header: FnHeader {
@@ -1594,7 +1594,7 @@ impl<'a> Parser<'a> {
                     abi,
                     asyncness,
                 },
-                decl: d,
+                decl,
             };
 
             let body = match self.token {
@@ -2319,7 +2319,8 @@ impl<'a> Parser<'a> {
         let ident = self.parse_path_segment_ident()?;
 
         let is_args_start = |token: &token::Token| match *token {
-            token::Lt | token::BinOp(token::Shl) | token::OpenDelim(token::Paren) => true,
+            token::Lt | token::BinOp(token::Shl) | token::OpenDelim(token::Paren)
+            | token::LArrow => true,
             _ => false,
         };
         let check_args_start = |this: &mut Self| {
@@ -6056,8 +6057,6 @@ impl<'a> Parser<'a> {
                         self.fatal("identifiers may currently not be used for const generics")
                     );
                 } else {
-                    // FIXME(const_generics): this currently conflicts with emplacement syntax
-                    // with negative integer literals.
                     self.parse_literal_maybe_minus()?
                 };
                 let value = AnonConst {
@@ -6475,10 +6474,10 @@ impl<'a> Parser<'a> {
                      -> PResult<'a, ItemInfo> {
         let (ident, mut generics) = self.parse_fn_header()?;
         let allow_c_variadic = abi == Abi::C && unsafety == Unsafety::Unsafe;
-        let decl = self.parse_fn_decl(allow_c_variadic)?;
+        let mut decl = self.parse_fn_decl(allow_c_variadic)?;
         generics.where_clause = self.parse_where_clause()?;
         let (inner_attrs, body) = self.parse_inner_attrs_and_block()?;
-        self.construct_async_arguments(&mut asyncness, &decl);
+        self.construct_async_arguments(&mut asyncness, &mut decl);
         let header = FnHeader { unsafety, asyncness, constness, abi };
         Ok((ident, ItemKind::Fn(decl, header, generics, body), Some(inner_attrs)))
     }
@@ -6662,9 +6661,9 @@ impl<'a> Parser<'a> {
             let (constness, unsafety, mut asyncness, abi) = self.parse_fn_front_matter()?;
             let ident = self.parse_ident()?;
             let mut generics = self.parse_generics()?;
-            let decl = self.parse_fn_decl_with_self(|p| p.parse_arg())?;
+            let mut decl = self.parse_fn_decl_with_self(|p| p.parse_arg())?;
             generics.where_clause = self.parse_where_clause()?;
-            self.construct_async_arguments(&mut asyncness, &decl);
+            self.construct_async_arguments(&mut asyncness, &mut decl);
             *at_end = true;
             let (inner_attrs, body) = self.parse_inner_attrs_and_block()?;
             let header = ast::FnHeader { abi, unsafety, constness, asyncness };
@@ -8710,9 +8709,9 @@ impl<'a> Parser<'a> {
     ///
     /// The arguments of the function are replaced in HIR lowering with the arguments created by
     /// this function and the statements created here are inserted at the top of the closure body.
-    fn construct_async_arguments(&mut self, asyncness: &mut Spanned<IsAsync>, decl: &FnDecl) {
+    fn construct_async_arguments(&mut self, asyncness: &mut Spanned<IsAsync>, decl: &mut FnDecl) {
         if let IsAsync::Async { ref mut arguments, .. } = asyncness.node {
-            for (index, input) in decl.inputs.iter().enumerate() {
+            for (index, input) in decl.inputs.iter_mut().enumerate() {
                 let id = ast::DUMMY_NODE_ID;
                 let span = input.pat.span;
 
@@ -8724,8 +8723,10 @@ impl<'a> Parser<'a> {
                 // `let <pat> = __argN;` statement, instead just adding a `let <pat> = <pat>;`
                 // statement.
                 let (binding_mode, ident, is_simple_pattern) = match input.pat.node {
-                    PatKind::Ident(binding_mode, ident, _) => (binding_mode, ident, true),
-                    _ => (BindingMode::ByValue(Mutability::Immutable), ident, false),
+                    PatKind::Ident(binding_mode @ BindingMode::ByValue(_), ident, _) => {
+                        (binding_mode, ident, true)
+                    }
+                    _ => (BindingMode::ByValue(Mutability::Mutable), ident, false),
                 };
 
                 // Construct an argument representing `__argN: <ty>` to replace the argument of the
@@ -8792,6 +8793,15 @@ impl<'a> Parser<'a> {
                     })
                 };
 
+                // Remove mutability from arguments. If this is not a simple pattern,
+                // those arguments are replaced by `__argN`, so there is no need to do this.
+                if let PatKind::Ident(BindingMode::ByValue(mutability @ Mutability::Mutable), ..) =
+                    &mut input.pat.node
+                {
+                    assert!(is_simple_pattern);
+                    *mutability = Mutability::Immutable;
+                }
+
                 let move_stmt = Stmt { id, node: StmtKind::Local(P(move_local)), span };
                 arguments.push(AsyncArgument { ident, arg, pat_stmt, move_stmt });
             }
diff --git a/src/test/ui/async-await/argument-patterns.rs b/src/test/ui/async-await/argument-patterns.rs
new file mode 100644
index 00000000000..3750c2bcb70
--- /dev/null
+++ b/src/test/ui/async-await/argument-patterns.rs
@@ -0,0 +1,30 @@
+// edition:2018
+// run-pass
+
+#![allow(unused_variables)]
+#![deny(unused_mut)]
+#![feature(async_await)]
+
+type A = Vec<u32>;
+
+async fn a(n: u32, mut vec: A) {
+    vec.push(n);
+}
+
+async fn b(n: u32, ref mut vec: A) {
+    vec.push(n);
+}
+
+async fn c(ref vec: A) {
+    vec.contains(&0);
+}
+
+async fn d((a, mut b): (A, A)) {
+    b.push(1);
+}
+
+async fn f((ref mut a, ref b): (A, A)) {}
+
+async fn g(((ref a, ref mut b), (ref mut c, ref d)): ((A, A), (A, A))) {}
+
+fn main() {}
diff --git a/src/test/ui/async-await/drop-order-for-async-fn-parameters-by-ref-binding.rs b/src/test/ui/async-await/drop-order-for-async-fn-parameters-by-ref-binding.rs
new file mode 100644
index 00000000000..c2b59eecb99
--- /dev/null
+++ b/src/test/ui/async-await/drop-order-for-async-fn-parameters-by-ref-binding.rs
@@ -0,0 +1,271 @@
+// aux-build:arc_wake.rs
+// edition:2018
+// run-pass
+
+#![allow(unused_variables)]
+#![feature(async_await, await_macro)]
+
+// Test that the drop order for parameters in a fn and async fn matches up. Also test that
+// parameters (used or unused) are not dropped until the async fn completes execution.
+// See also #54716.
+
+extern crate arc_wake;
+
+use arc_wake::ArcWake;
+use std::cell::RefCell;
+use std::future::Future;
+use std::marker::PhantomData;
+use std::sync::Arc;
+use std::rc::Rc;
+use std::task::Context;
+
+struct EmptyWaker;
+
+impl ArcWake for EmptyWaker {
+    fn wake(self: Arc<Self>) {}
+}
+
+#[derive(Debug, Eq, PartialEq)]
+enum DropOrder {
+    Function,
+    Val(&'static str),
+}
+
+type DropOrderListPtr = Rc<RefCell<Vec<DropOrder>>>;
+
+struct D(&'static str, DropOrderListPtr);
+
+impl Drop for D {
+    fn drop(&mut self) {
+        self.1.borrow_mut().push(DropOrder::Val(self.0));
+    }
+}
+
+/// Check that unused bindings are dropped after the function is polled.
+async fn foo_async(ref mut x: D, ref mut _y: D) {
+    x.1.borrow_mut().push(DropOrder::Function);
+}
+
+fn foo_sync(ref mut x: D, ref mut _y: D) {
+    x.1.borrow_mut().push(DropOrder::Function);
+}
+
+/// Check that underscore patterns are dropped after the function is polled.
+async fn bar_async(ref mut x: D, _: D) {
+    x.1.borrow_mut().push(DropOrder::Function);
+}
+
+fn bar_sync(ref mut x: D, _: D) {
+    x.1.borrow_mut().push(DropOrder::Function);
+}
+
+/// Check that underscore patterns within more complex patterns are dropped after the function
+/// is polled.
+async fn baz_async((ref mut x, _): (D, D)) {
+    x.1.borrow_mut().push(DropOrder::Function);
+}
+
+fn baz_sync((ref mut x, _): (D, D)) {
+    x.1.borrow_mut().push(DropOrder::Function);
+}
+
+/// Check that underscore and unused bindings within and outwith more complex patterns are dropped
+/// after the function is polled.
+async fn foobar_async(ref mut x: D, (ref mut a, _, ref mut _c): (D, D, D), _: D, ref mut _y: D) {
+    x.1.borrow_mut().push(DropOrder::Function);
+}
+
+fn foobar_sync(ref mut x: D, (ref mut a, _, ref mut _c): (D, D, D), _: D, ref mut _y: D) {
+    x.1.borrow_mut().push(DropOrder::Function);
+}
+
+struct Foo;
+
+impl Foo {
+    /// Check that unused bindings are dropped after the method is polled.
+    async fn foo_async(ref mut x: D, ref mut _y: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    fn foo_sync(ref mut x: D, ref mut _y: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    /// Check that underscore patterns are dropped after the method is polled.
+    async fn bar_async(ref mut x: D, _: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    fn bar_sync(ref mut x: D, _: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    /// Check that underscore patterns within more complex patterns are dropped after the method
+    /// is polled.
+    async fn baz_async((ref mut x, _): (D, D)) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    fn baz_sync((ref mut x, _): (D, D)) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    /// Check that underscore and unused bindings within and outwith more complex patterns are
+    /// dropped after the method is polled.
+    async fn foobar_async(
+        ref mut x: D, (ref mut a, _, ref mut _c): (D, D, D), _: D, ref mut _y: D,
+    ) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    fn foobar_sync(
+        ref mut x: D, (ref mut a, _, ref mut _c): (D, D, D), _: D, ref mut _y: D,
+    ) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+}
+
+struct Bar<'a>(PhantomData<&'a ()>);
+
+impl<'a> Bar<'a> {
+    /// Check that unused bindings are dropped after the method with self is polled.
+    async fn foo_async(&'a self, ref mut x: D, ref mut _y: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    fn foo_sync(&'a self, ref mut x: D, ref mut _y: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    /// Check that underscore patterns are dropped after the method with self is polled.
+    async fn bar_async(&'a self, ref mut x: D, _: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    fn bar_sync(&'a self, ref mut x: D, _: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    /// Check that underscore patterns within more complex patterns are dropped after the method
+    /// with self is polled.
+    async fn baz_async(&'a self, (ref mut x, _): (D, D)) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    fn baz_sync(&'a self, (ref mut x, _): (D, D)) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    /// Check that underscore and unused bindings within and outwith more complex patterns are
+    /// dropped after the method with self is polled.
+    async fn foobar_async(
+        &'a self, ref mut x: D, (ref mut a, _, ref mut _c): (D, D, D), _: D, ref mut _y: D,
+    ) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    fn foobar_sync(
+        &'a self, ref mut x: D, (ref mut a, _, ref mut _c): (D, D, D), _: D, ref mut _y: D,
+    ) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+}
+
+fn assert_drop_order_after_poll<Fut: Future<Output = ()>>(
+    f: impl FnOnce(DropOrderListPtr) -> Fut,
+    g: impl FnOnce(DropOrderListPtr),
+) {
+    let empty = Arc::new(EmptyWaker);
+    let waker = ArcWake::into_waker(empty);
+    let mut cx = Context::from_waker(&waker);
+
+    let actual_order = Rc::new(RefCell::new(Vec::new()));
+    let mut fut = Box::pin(f(actual_order.clone()));
+    let _ = fut.as_mut().poll(&mut cx);
+
+    let expected_order = Rc::new(RefCell::new(Vec::new()));
+    g(expected_order.clone());
+
+    assert_eq!(*actual_order.borrow(), *expected_order.borrow());
+}
+
+fn main() {
+    // Free functions (see doc comment on function for what it tests).
+    assert_drop_order_after_poll(|l| foo_async(D("x", l.clone()), D("_y", l.clone())),
+                                 |l| foo_sync(D("x", l.clone()), D("_y", l.clone())));
+    assert_drop_order_after_poll(|l| bar_async(D("x", l.clone()), D("_", l.clone())),
+                                 |l| bar_sync(D("x", l.clone()), D("_", l.clone())));
+    assert_drop_order_after_poll(|l| baz_async((D("x", l.clone()), D("_", l.clone()))),
+                                 |l| baz_sync((D("x", l.clone()), D("_", l.clone()))));
+    assert_drop_order_after_poll(
+        |l| {
+            foobar_async(
+                D("x", l.clone()),
+                (D("a", l.clone()), D("_", l.clone()), D("_c", l.clone())),
+                D("_", l.clone()),
+                D("_y", l.clone()),
+            )
+        },
+        |l| {
+            foobar_sync(
+                D("x", l.clone()),
+                (D("a", l.clone()), D("_", l.clone()), D("_c", l.clone())),
+                D("_", l.clone()),
+                D("_y", l.clone()),
+            )
+        },
+    );
+
+    // Methods w/out self (see doc comment on function for what it tests).
+    assert_drop_order_after_poll(|l| Foo::foo_async(D("x", l.clone()), D("_y", l.clone())),
+                                 |l| Foo::foo_sync(D("x", l.clone()), D("_y", l.clone())));
+    assert_drop_order_after_poll(|l| Foo::bar_async(D("x", l.clone()), D("_", l.clone())),
+                                 |l| Foo::bar_sync(D("x", l.clone()), D("_", l.clone())));
+    assert_drop_order_after_poll(|l| Foo::baz_async((D("x", l.clone()), D("_", l.clone()))),
+                                 |l| Foo::baz_sync((D("x", l.clone()), D("_", l.clone()))));
+    assert_drop_order_after_poll(
+        |l| {
+            Foo::foobar_async(
+                D("x", l.clone()),
+                (D("a", l.clone()), D("_", l.clone()), D("_c", l.clone())),
+                D("_", l.clone()),
+                D("_y", l.clone()),
+            )
+        },
+        |l| {
+            Foo::foobar_sync(
+                D("x", l.clone()),
+                (D("a", l.clone()), D("_", l.clone()), D("_c", l.clone())),
+                D("_", l.clone()),
+                D("_y", l.clone()),
+            )
+        },
+    );
+
+    // Methods (see doc comment on function for what it tests).
+    let b = Bar(Default::default());
+    assert_drop_order_after_poll(|l| b.foo_async(D("x", l.clone()), D("_y", l.clone())),
+                                 |l| b.foo_sync(D("x", l.clone()), D("_y", l.clone())));
+    assert_drop_order_after_poll(|l| b.bar_async(D("x", l.clone()), D("_", l.clone())),
+                                 |l| b.bar_sync(D("x", l.clone()), D("_", l.clone())));
+    assert_drop_order_after_poll(|l| b.baz_async((D("x", l.clone()), D("_", l.clone()))),
+                                 |l| b.baz_sync((D("x", l.clone()), D("_", l.clone()))));
+    assert_drop_order_after_poll(
+        |l| {
+            b.foobar_async(
+                D("x", l.clone()),
+                (D("a", l.clone()), D("_", l.clone()), D("_c", l.clone())),
+                D("_", l.clone()),
+                D("_y", l.clone()),
+            )
+        },
+        |l| {
+            b.foobar_sync(
+                D("x", l.clone()),
+                (D("a", l.clone()), D("_", l.clone()), D("_c", l.clone())),
+                D("_", l.clone()),
+                D("_y", l.clone()),
+            )
+        },
+    );
+}
diff --git a/src/test/ui/async-await/drop-order-locals-are-hidden.rs b/src/test/ui/async-await/drop-order-locals-are-hidden.rs
index 10dc5e27f6f..bcdb8878eb5 100644
--- a/src/test/ui/async-await/drop-order-locals-are-hidden.rs
+++ b/src/test/ui/async-await/drop-order-locals-are-hidden.rs
@@ -8,4 +8,9 @@ async fn foobar_async(x: u32, (a, _, _c): (u32, u32, u32), _: u32, _y: u32) {
     assert_eq!(__arg2, 4); //~ ERROR cannot find value `__arg2` in this scope [E0425]
 }
 
+async fn baz_async(ref mut x: u32, ref y: u32) {
+    assert_eq!(__arg0, 1); //~ ERROR cannot find value `__arg0` in this scope [E0425]
+    assert_eq!(__arg1, 2); //~ ERROR cannot find value `__arg1` in this scope [E0425]
+}
+
 fn main() {}
diff --git a/src/test/ui/async-await/drop-order-locals-are-hidden.stderr b/src/test/ui/async-await/drop-order-locals-are-hidden.stderr
index ca0da6b7c96..484e1f4f426 100644
--- a/src/test/ui/async-await/drop-order-locals-are-hidden.stderr
+++ b/src/test/ui/async-await/drop-order-locals-are-hidden.stderr
@@ -10,6 +10,18 @@ error[E0425]: cannot find value `__arg2` in this scope
 LL |     assert_eq!(__arg2, 4);
    |                ^^^^^^ not found in this scope
 
-error: aborting due to 2 previous errors
+error[E0425]: cannot find value `__arg0` in this scope
+  --> $DIR/drop-order-locals-are-hidden.rs:12:16
+   |
+LL |     assert_eq!(__arg0, 1);
+   |                ^^^^^^ not found in this scope
+
+error[E0425]: cannot find value `__arg1` in this scope
+  --> $DIR/drop-order-locals-are-hidden.rs:13:16
+   |
+LL |     assert_eq!(__arg1, 2);
+   |                ^^^^^^ not found in this scope
+
+error: aborting due to 4 previous errors
 
 For more information about this error, try `rustc --explain E0425`.
diff --git a/src/test/ui/async-await/mutable-arguments.rs b/src/test/ui/async-await/mutable-arguments.rs
deleted file mode 100644
index 4d6dba74097..00000000000
--- a/src/test/ui/async-await/mutable-arguments.rs
+++ /dev/null
@@ -1,10 +0,0 @@
-// edition:2018
-// run-pass
-
-#![feature(async_await)]
-
-async fn foo(n: u32, mut vec: Vec<u32>) {
-    vec.push(n);
-}
-
-fn main() {}
diff --git a/src/test/ui/const-generics/const-expression-parameter.rs b/src/test/ui/const-generics/const-expression-parameter.rs
index 662c7b767ba..22c6c351622 100644
--- a/src/test/ui/const-generics/const-expression-parameter.rs
+++ b/src/test/ui/const-generics/const-expression-parameter.rs
@@ -6,7 +6,7 @@ fn i32_identity<const X: i32>() -> i32 {
 }
 
 fn foo_a() {
-    i32_identity::<-1>(); //~ ERROR expected identifier, found `<-`
+    i32_identity::<-1>(); // ok
 }
 
 fn foo_b() {
diff --git a/src/test/ui/const-generics/const-expression-parameter.stderr b/src/test/ui/const-generics/const-expression-parameter.stderr
index 2f7a80f0c8f..c255127c280 100644
--- a/src/test/ui/const-generics/const-expression-parameter.stderr
+++ b/src/test/ui/const-generics/const-expression-parameter.stderr
@@ -1,9 +1,3 @@
-error: expected identifier, found `<-`
-  --> $DIR/const-expression-parameter.rs:9:19
-   |
-LL |     i32_identity::<-1>();
-   |                   ^^ expected identifier
-
 error: expected one of `,` or `>`, found `+`
   --> $DIR/const-expression-parameter.rs:13:22
    |
@@ -16,5 +10,5 @@ warning: the feature `const_generics` is incomplete and may cause the compiler t
 LL | #![feature(const_generics)]
    |            ^^^^^^^^^^^^^^
 
-error: aborting due to 2 previous errors
+error: aborting due to previous error