[NamedLazyMemberLoading] Bail on cases that interact with protocol member mirroring.

Author: graydon

lib/ClangImporter/ClangImporter.cpp

@@ -3280,6 +3280,20 @@ ClangImporter::Implementation::loadNamedMembers(
   auto *CD = D->getClangDecl();
   assert(CD && "loadNamedMembers on a Decl without a clangDecl");
 
+
+  // FIXME: The legacy of mirroring protocol members rears its ugly head,
+  // and as a result we have to bail on any @interface or @category that
+  // has a declared protocol conformance.
+  if (auto *ID = dyn_cast<clang::ObjCInterfaceDecl>(CD)) {
+    if (ID->protocol_begin() != ID->protocol_end())
+      return None;
+  }
+  if (auto *CCD = dyn_cast<clang::ObjCCategoryDecl>(CD)) {
+    if (CCD->protocol_begin() != CCD->protocol_end())
+      return None;
+  }
+
+
   // There are 3 cases:
   //
   //  - The decl is from a bridging header, CMO is Some(nullptr)

test/NameBinding/Inputs/NamedLazyMembers/NamedLazyMembers.h

@@ -50,3 +50,28 @@
 
 @end
 
+
+@protocol MirroredBase
++ (void)mirroredBaseClassMethod;
+- (void)mirroredBaseInstanceMethod;
+@end
+
+@protocol MirroredDoer <MirroredBase>
++ (void)mirroredDerivedClassMethod;
+- (void)mirroredDerivedInstanceMethod;
+@end
+
+@interface MirroringDoer : NSObject<MirroredDoer>
+- (void)unobtrusivelyGoForWalk;
+- (void)unobtrusivelyTakeNap;
+- (void)unobtrusivelyEatMeal;
+- (void)unobtrusivelyTidyHome;
+- (void)unobtrusivelyCallFamily;
+- (void)unobtrusivelySingSong;
+- (void)unobtrusivelyReadBook;
+- (void)unobtrusivelyAttendLecture;
+- (void)unobtrusivelyWriteLetter;
+@end
+
+@interface DerivedFromMirroringDoer : MirroringDoer
+@end

test/NameBinding/named_lazy_member_loading_objc_protocol.swift

@@ -8,7 +8,7 @@
 // Check that named-lazy-member-loading reduces the number of Decls deserialized
 // RUN: %target-swift-frontend -typecheck -I %S/Inputs/NamedLazyMembers -disable-named-lazy-member-loading -stats-output-dir %t/stats-pre %s
 // RUN: %target-swift-frontend -typecheck -I %S/Inputs/NamedLazyMembers -stats-output-dir %t/stats-post %s
-// RUN: %utils/process-stats-dir.py --evaluate-delta 'NumTotalClangImportedEntities < -10' %t/stats-pre %t/stats-post
+// RUN: %utils/process-stats-dir.py --evaluate-delta 'NumTotalClangImportedEntities < -9' %t/stats-pre %t/stats-post
 
 import NamedLazyMembers
 

test/NameBinding/named_lazy_member_loading_protocol_mirroring.swift

@@ -0,0 +1,26 @@
+// REQUIRES: objc_interop
+// REQUIRES: OS=macosx
+// RUN: rm -rf %t && mkdir -p %t/stats-pre && mkdir -p %t/stats-post
+//
+// Prime module cache
+// RUN: %target-swift-frontend -typecheck -I %S/Inputs/NamedLazyMembers -typecheck %s
+//
+// Check that named-lazy-member-loading reduces the number of Decls deserialized
+// RUN: %target-swift-frontend -typecheck -I %S/Inputs/NamedLazyMembers -disable-named-lazy-member-loading -stats-output-dir %t/stats-pre %s
+// RUN: %target-swift-frontend -typecheck -I %S/Inputs/NamedLazyMembers -stats-output-dir %t/stats-post %s
+
+import NamedLazyMembers
+
+public func foo(d: MirroringDoer) {
+  let _ = MirroringDoer.mirroredBaseClassMethod()
+  let _ = MirroringDoer.mirroredDerivedClassMethod()
+  let _ = d.mirroredBaseInstanceMethod()
+  let _ = d.mirroredDerivedInstanceMethod()
+}
+
+public func foo(d: DerivedFromMirroringDoer) {
+  let _ = MirroringDoer.mirroredBaseClassMethod()
+  let _ = MirroringDoer.mirroredDerivedClassMethod()
+  let _ = d.mirroredBaseInstanceMethod()
+  let _ = d.mirroredDerivedInstanceMethod()
+}