Auto merge of #2715 - RalfJung:rustup, r=RalfJung

[rust.git] / compiler / rustc_hir_typeck / src / callee.rs

diff --git a/compiler/rustc_hir_typeck/src/callee.rs b/compiler/rustc_hir_typeck/src/callee.rs
index 25b6cf4ef2e3ec62ce92f207946a8780ee75752f..b09ddf80e2a52577292e3d602fca7e3cff198dc2 100644 (file)
--- a/compiler/rustc_hir_typeck/src/callee.rs
+++ b/compiler/rustc_hir_typeck/src/callee.rs
@@ -179,12 +179,16 @@ fn try_overloaded_call_step(
 
             // Hack: we know that there are traits implementing Fn for &F
             // where F:Fn and so forth. In the particular case of types
-            // like `x: &mut FnMut()`, if there is a call `x()`, we would
-            // normally translate to `FnMut::call_mut(&mut x, ())`, but
-            // that winds up requiring `mut x: &mut FnMut()`. A little
-            // over the top. The simplest fix by far is to just ignore
-            // this case and deref again, so we wind up with
-            // `FnMut::call_mut(&mut *x, ())`.
+            // like `f: &mut FnMut()`, if there is a call `f()`, we would
+            // normally translate to `FnMut::call_mut(&mut f, ())`, but
+            // that winds up potentially requiring the user to mark their
+            // variable as `mut` which feels unnecessary and unexpected.
+            //
+            //     fn foo(f: &mut impl FnMut()) { f() }
+            //            ^ without this hack `f` would have to be declared as mutable
+            //
+            // The simplest fix by far is to just ignore this case and deref again,
+            // so we wind up with `FnMut::call_mut(&mut *f, ())`.
             ty::Ref(..) if autoderef.step_count() == 0 => {
                 return None;
             }
@@ -257,15 +261,11 @@ fn try_overloaded_call_traits(
                         return None;
                     };
 
-                    let mutbl = match mutbl {
-                        hir::Mutability::Not => AutoBorrowMutability::Not,
-                        hir::Mutability::Mut => AutoBorrowMutability::Mut {
-                            // For initial two-phase borrow
-                            // deployment, conservatively omit
-                            // overloaded function call ops.
-                            allow_two_phase_borrow: AllowTwoPhase::No,
-                        },
-                    };
+                    // For initial two-phase borrow
+                    // deployment, conservatively omit
+                    // overloaded function call ops.
+                    let mutbl = AutoBorrowMutability::new(*mutbl, AllowTwoPhase::No);
+
                     autoref = Some(Adjustment {
                         kind: Adjust::Borrow(AutoBorrow::Ref(*region, mutbl)),
                         target: method.sig.inputs()[0],
@@ -448,7 +448,7 @@ fn confirm_builtin_call(
         // previously appeared within a `Binder<>` and hence would not
         // have been normalized before.
         let fn_sig = self.replace_bound_vars_with_fresh_vars(call_expr.span, infer::FnCall, fn_sig);
-        let fn_sig = self.normalize_associated_types_in(call_expr.span, fn_sig);
+        let fn_sig = self.normalize(call_expr.span, fn_sig);
 
         // Call the generic checker.
         let expected_arg_tys = self.expected_inputs_for_expected_output(