[IRGen] Use symbolic references to (file)private entities in mangled names

lib/IRGen/IRGenMangler.cpp

@@ -101,7 +101,10 @@ IRGenMangler::withSymbolicReferences(IRGenModule &IGM,
       // TODO: We ought to be able to use indirect symbolic references even
       // when the referent may be in another file, once the on-disk
       // ObjectMemoryReader can handle them.
-      if (!IGM.CurSourceFile || IGM.CurSourceFile != type->getParentSourceFile())
+      // Private entities are known to be accessible.
+      if (type->getEffectiveAccess() >= AccessLevel::Internal &&
+          (!IGM.CurSourceFile ||
+           IGM.CurSourceFile != type->getParentSourceFile()))
         return false;
 
       // @objc protocols don't have descriptors.
@@ -114,6 +117,7 @@ IRGenMangler::withSymbolicReferences(IRGenModule &IGM,
       llvm_unreachable("symbolic referent not handled");
     }
   };
+
   SymbolicReferences.clear();
 
   body();

test/IRGen/associated_type_witness.swift

@@ -1,6 +1,10 @@
 // RUN: %target-swift-frontend -assume-parsing-unqualified-ownership-sil -primary-file %s -emit-ir > %t.ll
 // RUN: %FileCheck %s -check-prefix=GLOBAL < %t.ll
 // RUN: %FileCheck %s < %t.ll
+
+// RUN: %target-swift-frontend -assume-parsing-unqualified-ownership-sil -primary-file %s -emit-ir -wmo -num-threads 1 > %t.ll.wmo
+// RUN: %FileCheck %s -check-prefix=GLOBAL < %t.ll.wmo
+// RUN: %FileCheck %s < %t.ll.wmo
 // REQUIRES: CPU=x86_64
 
 protocol P {}
@@ -12,6 +16,16 @@ protocol Assocked {
 
 struct Universal : P, Q {}
 
+
+// CHECK-LABEL: @"symbolic _____ 23associated_type_witness12OuterPrivate{{.*}}V" = linkonce_odr hidden constant
+// CHECK-SAME: @"$s23associated_type_witness12OuterPrivate{{.*}}5InnerE0V9InnermostVMn"
+private struct OuterPrivate {
+  struct InnerPrivate: HasSimpleAssoc {
+    struct Innermost { }
+    typealias Assoc = Innermost
+  }
+}
+
 // CHECK: [[ASSOC_TYPE_NAMES:@.*]] = private constant [29 x i8] c"OneAssoc TwoAssoc ThreeAssoc\00"
 // CHECK: @"$s23associated_type_witness18HasThreeAssocTypesMp" =
 // CHECK-SAME: [[ASSOC_TYPE_NAMES]] to i64
@@ -116,7 +130,6 @@ protocol HasSimpleAssoc {
 }
 protocol DerivedFromSimpleAssoc : HasSimpleAssoc {}
 
-
 //   Generic witness table pattern for GenericComputed : DerivedFromSimpleAssoc.
 // GLOBAL-LABEL: @"$s23associated_type_witness15GenericComputedVyxGAA22DerivedFromSimpleAssocAAWp" = internal constant [2 x i8*]
 // GLOBAL-SAME: @"$s23associated_type_witness15GenericComputedVyxGAA22DerivedFromSimpleAssocAAMc"

test/Runtime/associated_type_demangle_private.swift

@@ -0,0 +1,32 @@
+// RUN: %empty-directory(%t)
+// RUN: %target-build-swift -parse-stdlib %s -module-name main -o %t/a.out
+// RUN: %target-codesign %t/a.out
+// RUN: %target-run %t/a.out
+// REQUIRES: executable_test
+
+import Swift
+import StdlibUnittest
+
+protocol P {
+  associatedtype A
+}
+
+fileprivate struct Foo {
+  fileprivate struct Inner: P {
+    fileprivate struct Innermost { }
+    typealias A = Innermost
+  }
+}
+
+func getP_A<T: P>(_: T.Type) -> Any.Type {
+  return T.A.self
+}
+
+let AssociatedTypeDemangleTests = TestSuite("AssociatedTypeDemangle")
+
+
+AssociatedTypeDemangleTests.test("private types") {
+  expectEqual(Foo.Inner.Innermost.self, getP_A(Foo.Inner.self))
+}
+
+runAllTests()