Apply suggestions from oli-obk's review

Co-authored-by: Oli Scherer <github35764891676564198441@oli-obk.de>

Author: zetanumbers

compiler/rustc_codegen_ssa/src/back/symbol_export.rs

@@ -470,22 +470,16 @@ fn upstream_drop_glue_for_provider<'tcx>(
     tcx: TyCtxt<'tcx>,
     args: GenericArgsRef<'tcx>,
 ) -> Option<CrateNum> {
-    if let Some(def_id) = tcx.lang_items().drop_in_place_fn() {
-        tcx.upstream_monomorphizations_for(def_id).and_then(|monos| monos.get(&args).cloned())
-    } else {
-        None
-    }
+    let def_id = tcx.lang_items().drop_in_place_fn()?;
+    tcx.upstream_monomorphizations_for(def_id)?.get(&args).cloned()
 }
 
 fn upstream_async_drop_glue_for_provider<'tcx>(
     tcx: TyCtxt<'tcx>,
     args: GenericArgsRef<'tcx>,
 ) -> Option<CrateNum> {
-    if let Some(def_id) = tcx.lang_items().async_drop_in_place_fn() {
-        tcx.upstream_monomorphizations_for(def_id).and_then(|monos| monos.get(&args).cloned())
-    } else {
-        None
-    }
+    let def_id = tcx.lang_items().async_drop_in_place_fn()?;
+    tcx.upstream_monomorphizations_for(def_id)?.get(&args).cloned()
 }
 
 fn is_unreachable_local_definition_provider(tcx: TyCtxt<'_>, def_id: LocalDefId) -> bool {

compiler/rustc_middle/src/ty/instance.rs

@@ -314,7 +314,9 @@ impl<'tcx> InstanceKind<'tcx> {
         if self.requires_inline(tcx) {
             return true;
         }
-        if let ty::InstanceKind::DropGlue(.., Some(ty)) = *self {
+        if let ty::InstanceKind::DropGlue(.., Some(ty))
+        | ty::InstanceKind::AsyncDropGlueCtorShim(.., Some(ty)) = *self
+        {
             // Drop glue generally wants to be instantiated at every codegen
             // unit, but without an #[inline] hint. We should make this
             // available to normal end-users.
@@ -329,29 +331,14 @@ impl<'tcx> InstanceKind<'tcx> {
             // drops of `Option::None` before LTO. We also respect the intent of
             // `#[inline]` on `Drop::drop` implementations.
             return ty.ty_adt_def().map_or(true, |adt_def| {
-                adt_def
-                    .destructor(tcx)
-                    .map_or_else(|| adt_def.is_enum(), |dtor| tcx.cross_crate_inlinable(dtor.did))
-            });
-        }
-        if let ty::InstanceKind::AsyncDropGlueCtorShim(.., Some(ty)) = *self {
-            // Async drop glue generally wants to be instantiated at
-            // every codegen unit, but without an #[inline] hint. We
-            // should make this available to normal end-users.
-            if tcx.sess.opts.incremental.is_none() {
-                return true;
-            }
-            // When compiling with incremental, we can generate a *lot* of
-            // codegen units. Including drop glue into all of them has a
-            // considerable compile time cost.
-            //
-            // We include enums without destructors to allow, say, optimizing
-            // drops of `Option::None` before LTO. We also respect the intent of
-            // `#[inline]` on `Drop::drop` implementations.
-            return ty.ty_adt_def().map_or(true, |adt_def| {
-                adt_def
-                    .async_destructor(tcx)
-                    .map_or_else(|| adt_def.is_enum(), |dtor| tcx.cross_crate_inlinable(dtor.ctor))
+                match *self {
+                    ty::InstanceKind::DropGlue(..) => adt_def.destructor(tcx).map(|dtor| dtor.did),
+                    ty::InstanceKind::AsyncDropGlueCtorShim(..) => {
+                        adt_def.async_destructor(tcx).map(|dtor| dtor.ctor)
+                    }
+                    _ => unreachable!(),
+                }
+                .map_or_else(|| adt_def.is_enum(), |did| tcx.cross_crate_inlinable(did))
             });
         }
         if let ty::InstanceKind::ThreadLocalShim(..) = *self {