Stop using a special inner body for the coroutine by-move body for async closures

compiler/rustc_hir/src/def.rs

@@ -133,6 +133,9 @@ pub enum DefKind {
     /// we treat them all the same, and code which needs to distinguish them can match
     /// or `hir::ClosureKind` or `type_of`.
     Closure,
+    /// The definition of a synthetic coroutine body created by the lowering of a
+    /// coroutine-closure, such as an async closure.
+    SyntheticCoroutineBody,
 }
 
 impl DefKind {
@@ -177,6 +180,7 @@ impl DefKind {
             DefKind::Closure => "closure",
             DefKind::ExternCrate => "extern crate",
             DefKind::GlobalAsm => "global assembly block",
+            DefKind::SyntheticCoroutineBody => "synthetic mir body",
         }
     }
 
@@ -236,7 +240,8 @@ impl DefKind {
             | DefKind::ForeignMod
             | DefKind::GlobalAsm
             | DefKind::Impl { .. }
-            | DefKind::OpaqueTy => None,
+            | DefKind::OpaqueTy
+            | DefKind::SyntheticCoroutineBody => None,
         }
     }
 
@@ -276,6 +281,7 @@ impl DefKind {
             DefKind::GlobalAsm => DefPathData::GlobalAsm,
             DefKind::Impl { .. } => DefPathData::Impl,
             DefKind::Closure => DefPathData::Closure,
+            DefKind::SyntheticCoroutineBody => DefPathData::Closure,
         }
     }
 
@@ -291,7 +297,8 @@ impl DefKind {
             | DefKind::AssocFn
             | DefKind::Ctor(..)
             | DefKind::Closure
-            | DefKind::Static { .. } => true,
+            | DefKind::Static { .. }
+            | DefKind::SyntheticCoroutineBody => true,
             DefKind::Mod
             | DefKind::Struct
             | DefKind::Union