Mangling: relax the re-mangling verification check a little bit.

There are cases where the re-mangling doesn't yield the original mangled name.
This is no problem for the compiler as it only affects how mangling substitutions are handled.

rdar://problem/31539542

Author: eeckstein

lib/Basic/Mangler.cpp

@@ -163,20 +163,20 @@ void Mangler::verify(const std::string &mangledName) {
   if (Remangled == mangledName)
     return;
 
-  if (treeContains(Root,
-                   Demangle::Node::Kind::DependentAssociatedTypeRef)) {
-    // There are cases where dependent associated types results in different
-    // remangled names. See ASTMangler::appendAssociatedTypeName.
-    // This is no problem for the compiler, but we have to exclude this case
-    // for the check. Instead we try to re-de-mangle the remangled name.
-    nameStr = Remangled;
-    NodePointer RootOfRemangled = Dem.demangleSymbol(nameStr);
-    if (Remangled == mangleNode(RootOfRemangled))
-      return;
-  }
+  // There are cases (e.g. with dependent associated types) which results in
+  // different remangled names. See ASTMangler::appendAssociatedTypeName.
+  // This is no problem for the compiler, but we have to be more tolerant for
+  // those cases. Instead we try to re-de-mangle the remangled name.
+  nameStr = Remangled;
+  NodePointer RootOfRemangled = Dem.demangleSymbol(nameStr);
+  std::string ReDemangled = mangleNode(RootOfRemangled);
+  if (Remangled == ReDemangled)
+    return;
+
   llvm::errs() << "Remangling failed:\n"
-                  "original  = " << nameStr << "\n"
-                  "remangled = " << Remangled << '\n';
+                  "original     = " << nameStr << "\n"
+                  "remangled    = " << Remangled << "\n"
+                  "re-demangled = " << ReDemangled << '\n';
   abort();
 #endif
 }

test/Demangle/Inputs/manglings.txt

@@ -249,4 +249,5 @@ _T0s10DictionaryV3t17E6Index2V1loiSbAEyxq__G_AGtFZ ---> static (extension in t17
 _T08mangling14varargsVsArrayySaySiG3arrd_SS1ntF ---> mangling.varargsVsArray (arr : Swift.Int..., n : Swift.String) -> ()
 _T08mangling14varargsVsArrayySaySiG3arrd_tF ---> mangling.varargsVsArray (arr : Swift.Int...) -> ()
 _T0s13_UnicodeViewsVss22RandomAccessCollectionRzs0A8EncodingR_11SubSequence_5IndexQZAFRtzsAcERpzAE_AEQZAIRSs15UnsignedInteger8Iterator_7ElementRPzAE_AlMQZANRS13EncodedScalar_AlMQY_AORSr0_lE13CharacterViewVyxq__G ---> (extension in Swift):Swift._UnicodeViews<A, B><A, B where A: Swift.RandomAccessCollection, B: Swift.UnicodeEncoding, A.Index == A.SubSequence.Index, A.SubSequence: Swift.RandomAccessCollection, A.SubSequence == A.SubSequence.SubSequence, A.Iterator.Element: Swift.UnsignedInteger, A.Iterator.Element == A.SubSequence.Iterator.Element, A.SubSequence.Iterator.Element == B.EncodedScalar.Iterator.Element>.CharacterView
+_T010Foundation11MeasurementV12SimulatorKitSo9UnitAngleCRszlE11OrientationO2eeoiSbAcDEAGOyAF_G_AKtFZ ---> static (extension in SimulatorKit):Foundation.Measurement<A where A == __ObjC.UnitAngle>.Orientation.== infix ((extension in SimulatorKit):Foundation.Measurement<__ObjC.UnitAngle>.Orientation, (extension in SimulatorKit):Foundation.Measurement<__ObjC.UnitAngle>.Orientation) -> Swift.Bool