[PATCH] D29880: Workaround MSVC bug when using TrailingObjects from a template.

[James Y Knight via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rL296497: Workaround MSVC bug when using TrailingObjects from a template. (authored by jyknight).

Changed prior to commit:
  https://reviews.llvm.org/D29880?vs=88154&id=90054#toc

Repository:
  rL LLVM

https://reviews.llvm.org/D29880

Files:
  llvm/trunk/include/llvm/Support/TrailingObjects.h
  llvm/trunk/unittests/Support/TrailingObjectsTest.cpp


Index: llvm/trunk/include/llvm/Support/TrailingObjects.h
===================================================================
--- llvm/trunk/include/llvm/Support/TrailingObjects.h
+++ llvm/trunk/include/llvm/Support/TrailingObjects.h
@@ -294,7 +294,14 @@
 
 public:
   // Make this (privately inherited) member public.
+#ifndef _MSC_VER
   using ParentType::OverloadToken;
+#else
+  // MSVC bug prevents the above from working, at least up through CL
+  // 19.10.24629.
+  template <typename T>
+  using OverloadToken = typename ParentType::template OverloadToken<T>;
+#endif
 
   /// Returns a pointer to the trailing object array of the given type
   /// (which must be one of those specified in the class template). The
Index: llvm/trunk/unittests/Support/TrailingObjectsTest.cpp
===================================================================
--- llvm/trunk/unittests/Support/TrailingObjectsTest.cpp
+++ llvm/trunk/unittests/Support/TrailingObjectsTest.cpp
@@ -236,3 +236,24 @@
                 reinterpret_cast<char *>(C + 1) + 1, alignof(long))));
 }
 }
+
+// Test the use of TrailingObjects with a template class. This
+// previously failed to compile due to a bug in MSVC's member access
+// control/lookup handling for OverloadToken.
+template <typename Derived>
+class Class5Tmpl : private llvm::TrailingObjects<Derived, float, int> {
+  using TrailingObjects = typename llvm::TrailingObjects<Derived, float>;
+  friend TrailingObjects;
+
+  size_t numTrailingObjects(
+      typename TrailingObjects::template OverloadToken<float>) const {
+    return 1;
+  }
+
+  size_t numTrailingObjects(
+      typename TrailingObjects::template OverloadToken<int>) const {
+    return 2;
+  }
+};
+
+class Class5 : public Class5Tmpl<Class5> {};


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