[move-only] When emitting a module, do not emit the body of the deinit of a move only type.

rdar://102173152

Author: gottesmm

lib/SILGen/SILGen.cpp

@@ -1590,9 +1590,12 @@ void SILGenModule::emitMoveOnlyDestructor(NominalTypeDecl *cd,
 
   emitAbstractFuncDecl(dd);
 
-  // Emit the deallocating destructor.
-  SILDeclRef deallocator(dd, SILDeclRef::Kind::Deallocator);
-  emitFunctionDefinition(deallocator, getFunction(deallocator, ForDefinition));
+  // Emit the deallocating destructor if we have a body.
+  if (dd->hasBody()) {
+    SILDeclRef deallocator(dd, SILDeclRef::Kind::Deallocator);
+    emitFunctionDefinition(deallocator,
+                           getFunction(deallocator, ForDefinition));
+  }
 }
 
 void SILGenModule::emitDefaultArgGenerator(SILDeclRef constant,

test/SILGen/moveonly_deinit_module_no_body.swift

@@ -0,0 +1,15 @@
+// RUN: %target-swift-frontend -emit-module -g -enable-experimental-move-only -experimental-skip-non-inlinable-function-bodies-without-types %s 
+
+// Just make sure we don't crash.
+
+@_moveOnly
+public struct S {
+  private let desc: Int
+
+  internal init(desc: Int) {
+    self.desc = desc
+  }
+
+  deinit {
+  }
+}