diff --git a/compiler/rustc_incremental/messages.ftl b/compiler/rustc_incremental/messages.ftl
index de2177ebb6e..2a65101d360 100644
--- a/compiler/rustc_incremental/messages.ftl
+++ b/compiler/rustc_incremental/messages.ftl
@@ -99,6 +99,4 @@ incremental_unrecognized_depnode = unrecognized `DepNode` variant: {$name}
 
 incremental_unrecognized_depnode_label = dep-node label `{$label}` not recognized
 
-incremental_write_dep_graph = failed to write dependency graph to `{$path}`: {$err}
-
 incremental_write_new = failed to write {$name} to `{$path}`: {$err}
diff --git a/compiler/rustc_incremental/src/errors.rs b/compiler/rustc_incremental/src/errors.rs
index b68c149d398..c6f8b99bcd6 100644
--- a/compiler/rustc_incremental/src/errors.rs
+++ b/compiler/rustc_incremental/src/errors.rs
@@ -272,13 +272,6 @@ pub struct LoadDepGraph {
     pub err: std::io::Error,
 }
 
-#[derive(Diagnostic)]
-#[diag(incremental_write_dep_graph)]
-pub struct WriteDepGraph<'a> {
-    pub path: &'a Path,
-    pub err: std::io::Error,
-}
-
 #[derive(Diagnostic)]
 #[diag(incremental_move_dep_graph)]
 pub struct MoveDepGraph<'a> {
diff --git a/compiler/rustc_passes/messages.ftl b/compiler/rustc_passes/messages.ftl
index dfc726efeb9..bdc229a6c09 100644
--- a/compiler/rustc_passes/messages.ftl
+++ b/compiler/rustc_passes/messages.ftl
@@ -481,10 +481,6 @@ passes_must_not_suspend =
     `must_not_suspend` attribute should be applied to a struct, enum, union, or trait
     .label = is not a struct, enum, union, or trait
 
-passes_must_use_async =
-    `must_use` attribute on `async` functions applies to the anonymous `Future` returned by the function, not the value within
-    .label = this attribute does nothing, the `Future`s returned by async functions are already `must_use`
-
 passes_must_use_no_effect =
     `#[must_use]` has no effect when applied to {$article} {$target}
 
diff --git a/compiler/rustc_passes/src/errors.rs b/compiler/rustc_passes/src/errors.rs
index 1190e60f41f..644ae23a761 100644
--- a/compiler/rustc_passes/src/errors.rs
+++ b/compiler/rustc_passes/src/errors.rs
@@ -371,13 +371,6 @@ pub struct FfiConstInvalidTarget {
     pub attr_span: Span,
 }
 
-#[derive(LintDiagnostic)]
-#[diag(passes_must_use_async)]
-pub struct MustUseAsync {
-    #[label]
-    pub span: Span,
-}
-
 #[derive(LintDiagnostic)]
 #[diag(passes_must_use_no_effect)]
 pub struct MustUseNoEffect {
diff --git a/compiler/rustc_transmute/src/maybe_transmutable/query_context.rs b/compiler/rustc_transmute/src/maybe_transmutable/query_context.rs
index 95373916a71..f8b59bdf326 100644
--- a/compiler/rustc_transmute/src/maybe_transmutable/query_context.rs
+++ b/compiler/rustc_transmute/src/maybe_transmutable/query_context.rs
@@ -4,7 +4,6 @@
 pub(crate) trait QueryContext {
     type Def: layout::Def;
     type Ref: layout::Ref;
-    type Scope: Copy;
 }
 
 #[cfg(test)]
@@ -28,20 +27,17 @@ fn has_safety_invariants(&self) -> bool {
     impl QueryContext for UltraMinimal {
         type Def = Def;
         type Ref = !;
-        type Scope = ();
     }
 }
 
 #[cfg(feature = "rustc")]
 mod rustc {
-    use rustc_middle::ty::{Ty, TyCtxt};
+    use rustc_middle::ty::TyCtxt;
 
     use super::*;
 
     impl<'tcx> super::QueryContext for TyCtxt<'tcx> {
         type Def = layout::rustc::Def<'tcx>;
         type Ref = layout::rustc::Ref<'tcx>;
-
-        type Scope = Ty<'tcx>;
     }
 }
diff --git a/library/alloc/tests/boxed.rs b/library/alloc/tests/boxed.rs
index faee64b2f67..bfc31a626fa 100644
--- a/library/alloc/tests/boxed.rs
+++ b/library/alloc/tests/boxed.rs
@@ -59,6 +59,7 @@ fn box_deref_lval() {
     assert_eq!(x.get(), 1000);
 }
 
+#[allow(unused)]
 pub struct ConstAllocator;
 
 unsafe impl Allocator for ConstAllocator {