Index: clang/lib/Sema/SemaDeclCXX.cpp
===================================================================
--- clang/lib/Sema/SemaDeclCXX.cpp
+++ clang/lib/Sema/SemaDeclCXX.cpp
@@ -3427,6 +3427,9 @@
           << SourceRange(D.getName().TemplateId->LAngleLoc,
                          D.getName().TemplateId->RAngleLoc)
           << D.getName().TemplateId->LAngleLoc;
+      if (cast<CXXRecordDecl>(CurContext)->getDeclName() == Name)
+        Diag(Loc, diag::err_member_name_of_class) << Name;
+      D.setInvalidType();
     }
 
     if (SS.isSet() && !SS.isInvalid()) {
Index: clang/test/SemaCXX/PR28101.cpp
===================================================================
--- /dev/null
+++ clang/test/SemaCXX/PR28101.cpp
@@ -0,0 +1,53 @@
+// RUN: %clang_cc1 -fsyntax-only -verify -DCASE_1 %s
+// RUN: %clang_cc1 -fsyntax-only -verify -DCASE_2 %s
+// RUN: %clang_cc1 -fsyntax-only -verify -DCASE_3 %s
+// RUN: %clang_cc1 -fsyntax-only -verify -DCASE_4 -std=c++17 %s
+
+// Don't crash.
+
+#ifdef CASE_1
+
+template <typename T> struct A {
+  A(void *) {}
+  T(A<T>){}; // expected-error{{member 'A' cannot have template arguments}}\
+  // expected-error{{member 'A' has the same name as its class}}
+};
+
+A<int> instantiate() { return {nullptr}; }
+
+#elifdef CASE_2
+
+template <typename T> struct A {
+  A(void *) {}
+  T A<T>{}; // expected-error{{member 'A' cannot have template arguments}}\
+  // expected-error{{member 'A' has the same name as its class}}
+};
+
+A<int> instantiate() { return {nullptr}; }
+
+#elifdef CASE_3
+
+template <typename T> struct S {};
+
+template <typename T> struct A {
+  A(void *) {}
+  T S<T>{}; // expected-error{{member 'S' cannot have template arguments}}
+};
+
+A<int> instantiate() { return {nullptr}; }
+
+#elifdef CASE_4
+
+template <typename T, template <typename> typename U> class A {
+public:
+  A(void *) {}
+  T(A<T, U<T>>) {} // expected-error{{member 'A' cannot have template arguments}}\
+  // expected-error{{expected ';' at end of declaration list}}\
+  // expected-error{{member 'A' has the same name as its class}}
+};
+
+template <typename T> struct S {};
+
+A<int, S> foo() { return A<int, S>(nullptr); }
+
+#endif