re PR c++/71875 (template specialization compile error)

	PR c++/71875
	* g++.dg/cpp1y/pr71875.C: New test.

From-SVN: r253613

gcc/testsuite/ChangeLog

 2017-10-10  Jakub Jelinek  <jakub@redhat.com>
 
+	PR c++/71875
+	* g++.dg/cpp1y/pr71875.C: New test.
+
 	PR c++/77578
 	* g++.dg/gomp/pr77578.C: New test.
 

gcc/testsuite/g++.dg/cpp1y/pr71875.C

+// PR c++/71875
+// { dg-do link { target c++14 } }
+
+template <typename T>
+constexpr bool IsMatrix = false;
+
+template<typename TElem>
+class Matrix {};
+
+template <typename TElem>
+constexpr bool IsMatrix<Matrix<TElem>> = true;
+
+template<typename TNestVec>
+class RowVecExpMatrix;
+
+template <typename TNestVec>
+constexpr bool IsMatrix<RowVecExpMatrix<TNestVec>> = true;
+
+int
+main ()
+{
+  static_assert (IsMatrix<RowVecExpMatrix<Matrix<int>>>, "Matrix check error");
+  static_assert (IsMatrix<Matrix<int>>, "Input type is not a matrix");
+}