3 files changed, 13 insertions, 19 deletions
diff --git a/compiler/rustc_mir/src/borrow_check/diagnostics/mutability_errors.rs b/compiler/rustc_mir/src/borrow_check/diagnostics/mutability_errors.rs
index 28f6508cab2..d1fb999e518 100644
--- a/compiler/rustc_mir/src/borrow_check/diagnostics/mutability_errors.rs
+++ b/compiler/rustc_mir/src/borrow_check/diagnostics/mutability_errors.rs
@@ -642,15 +642,18 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
                                         .starts_with(&original_method_ident.name.to_string())
                             })
                             .map(|ident| format!("{}()", ident))
+                            .peekable()
                     });
 
-                if let Some(suggestions) = opt_suggestions {
-                    err.span_suggestions(
-                        path_segment.ident.span,
-                        &format!("use mutable method"),
-                        suggestions,
-                        Applicability::MaybeIncorrect,
-                    );
+                if let Some(mut suggestions) = opt_suggestions {
+                    if suggestions.peek().is_some() {
+                        err.span_suggestions(
+                            path_segment.ident.span,
+                            &format!("use mutable method"),
+                            suggestions,
+                            Applicability::MaybeIncorrect,
+                        );
+                    }
                 }
             }
         };
diff --git a/compiler/rustc_mir/src/interpret/memory.rs b/compiler/rustc_mir/src/interpret/memory.rs
index fe5ebf0b6fe..3648748a909 100644
--- a/compiler/rustc_mir/src/interpret/memory.rs
+++ b/compiler/rustc_mir/src/interpret/memory.rs
@@ -854,11 +854,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
             Some(ptr) => ptr,
             None => {
                 // zero-sized access
-                assert_matches!(
-                    src.next(),
-                    None,
-                    "iterator said it was empty but returned an element"
-                );
+                assert!(src.next().is_none(), "iterator said it was empty but returned an element");
                 return Ok(());
             }
         };
@@ -884,11 +880,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
             Some(ptr) => ptr,
             None => {
                 // zero-sized access
-                assert_matches!(
-                    src.next(),
-                    None,
-                    "iterator said it was empty but returned an element"
-                );
+                assert!(src.next().is_none(), "iterator said it was empty but returned an element");
                 return Ok(());
             }
         };
@@ -902,7 +894,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
             let offset_ptr = ptr.offset(Size::from_bytes(idx) * 2, &tcx)?; // `Size` multiplication
             allocation.write_scalar(&tcx, offset_ptr, val.into(), Size::from_bytes(2))?;
         }
-        assert_matches!(src.next(), None, "iterator was longer than it said it would be");
+        assert!(src.next().is_none(), "iterator was longer than it said it would be");
         Ok(())
     }
 
diff --git a/compiler/rustc_mir/src/lib.rs b/compiler/rustc_mir/src/lib.rs
index f73d5dc0c11..bf4eeb408ec 100644
--- a/compiler/rustc_mir/src/lib.rs
+++ b/compiler/rustc_mir/src/lib.rs
@@ -7,7 +7,6 @@ Rust MIR: a lowered representation of Rust.
 #![feature(nll)]
 #![feature(in_band_lifetimes)]
 #![feature(array_windows)]
-#![feature(assert_matches)]
 #![feature(bindings_after_at)]
 #![feature(bool_to_option)]
 #![feature(box_patterns)]