--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/clang/test/CodeGenCXX/template-instantiation.cpp	Thu Feb 13 15:10:13 2020 +0900
@@ -0,0 +1,205 @@
+// RUN: %clang_cc1 %s -O1 -disable-llvm-passes -triple=x86_64-apple-darwin10 -std=c++11 -emit-llvm -o - | FileCheck %s
+// RUN: %clang_cc1 %s -O1 -disable-llvm-passes -triple=x86_64-apple-darwin10 -std=c++11 -emit-llvm -o - | FileCheck %s --check-prefix=CHECK2
+
+// Instantiation order varies on different C++ dialects (IE, between C++98 and C++11).
+// CHECK-DAG: @_ZN7PR100011xE = global
+// CHECK-DAG: @_ZTVN5test018stdio_sync_filebufIA3_iEE = weak_odr unnamed_addr constant
+// CHECK-DAG: @_ZN7PR100011SIiE3arrE = linkonce_odr global [3 x i32]
+// CHECK-DAG: @_ZTVN5test018stdio_sync_filebufIA4_iEE = linkonce_odr unnamed_addr constant
+
+// Negative checks go under prefix "CHECK2" to avoid interference with CHECK and CHECK-DAG.
+// CHECK2-NOT: @_ZN7PR100014kBarE = external global i32
+// CHECK2-NOT: @_ZTVN5test118stdio_sync_filebufIwEE = constant
+// CHECK2-NOT: _ZTVN5test315basic_fstreamXXIcEE
+// CHECK2-NOT: @_ZTVN5test018stdio_sync_filebufIA1_iEE
+// CHECK2-NOT: @_ZTVN5test018stdio_sync_filebufIA2_iEE
+// CHECK2-NOT: @_ZN7PR100011SIiE3arr2E = linkonce_odr global [3 x i32]A
+
+// CHECK2-NOT: _ZTVN5test31SIiEE
+// CHECK2-NOT: _ZTSN5test31SIiEE
+
+// CHECK-LABEL: define linkonce_odr void @_ZN5test21CIiEC1Ev(%"class.test2::C"* %this) unnamed_addr
+// CHECK-LABEL: define linkonce_odr void @_ZN5test21CIiE6foobarIdEEvT_(
+// CHECK-LABEL: define available_externally void @_ZN5test21CIiE6zedbarEd(
+
+// CHECK-LABEL: define linkonce_odr void @_ZN7PR106662g1ENS_1SILi1EEE()
+// CHECK-LABEL: define linkonce_odr void @_ZN7PR106662g1ENS_1SILi2EEE()
+// CHECK-LABEL: define linkonce_odr void @_ZN7PR106662g1ENS_1SILi3EEE()
+// CHECK-LABEL: define linkonce_odr void @_ZN7PR106662g2ENS_1SILi1EEE()
+// CHECK-LABEL: define linkonce_odr void @_ZN7PR106662g2ENS_1SILi2EEE()
+// CHECK-LABEL: define linkonce_odr void @_ZN7PR106662g2ENS_1SILi3EEE()
+// CHECK: declare void @_ZN7PR106662h1ENS_1SILi1EEE()
+// CHECK: declare void @_ZN7PR106662h1ENS_1SILi2EEE()
+// CHECK: declare void @_ZN7PR106662h1ENS_1SILi3EEE()
+// CHECK: declare void @_ZN7PR106662h2ENS_1SILi1EEE()
+// CHECK: declare void @_ZN7PR106662h2ENS_1SILi2EEE()
+// CHECK: declare void @_ZN7PR106662h2ENS_1SILi3EEE()
+
+namespace test0 {
+  struct  basic_streambuf   {
+    virtual       ~basic_streambuf();
+  };
+  template<typename _CharT >
+  struct stdio_sync_filebuf : public basic_streambuf {
+    virtual void      xsgetn();
+  };
+
+  // This specialization is not a key function, so doesn't cause the vtable to
+  // be instantiated unless we're instantiating a class definition anyway.
+  template<> void stdio_sync_filebuf<int[1]>::xsgetn()  {
+  }
+  template<> void stdio_sync_filebuf<int[2]>::xsgetn()  {
+  }
+  template<> void stdio_sync_filebuf<int[3]>::xsgetn()  {
+  }
+  template<> void stdio_sync_filebuf<int[4]>::xsgetn()  {
+  }
+  extern template class stdio_sync_filebuf<int[2]>;
+
+  // These two both cause vtables to be emitted.
+  template class stdio_sync_filebuf<int[3]>;
+  stdio_sync_filebuf<int[4]> implicit_instantiation;
+}
+
+namespace test1 {
+  struct  basic_streambuf   {
+    virtual       ~basic_streambuf();
+  };
+  template<typename _CharT >
+  struct stdio_sync_filebuf : public basic_streambuf {
+    virtual void      xsgetn();
+  };
+
+  // Just a declaration should not force the vtable to be emitted.
+  template<> void stdio_sync_filebuf<wchar_t>::xsgetn();
+}
+
+namespace test2 {
+  template<typename T1>
+  class C {
+  public:
+    virtual ~C();
+    void zedbar(double) {
+    }
+    template<typename T2>
+    void foobar(T2 foo) {
+    }
+  };
+  extern template class C<int>;
+  void g() {
+    // The extern template declaration should not prevent us from producing
+    // the implicit constructor (test at the top).
+    C<int> a;
+
+    // or foobar(test at the top).
+    a.foobar(0.0);
+
+    // But it should prevent zebbar
+    // (test at the top).
+    a.zedbar(0.0);
+  }
+}
+
+namespace test3 {
+  template<typename T>
+  class basic_fstreamXX  {
+    virtual void foo(){}
+    virtual void is_open() const  { }
+  };
+
+  extern template class basic_fstreamXX<char>;
+  // This template instantiation should not cause us to produce a vtable.
+  // (test at the top).
+  template void basic_fstreamXX<char>::is_open() const;
+}
+
+namespace test3 {
+  template <typename T>
+  struct S  {
+      virtual void m();
+  };
+  
+  template<typename T>
+  void S<T>::m() { }
+
+  // Should not cause us to produce vtable because template instantiations
+  // don't have key functions.
+  template void S<int>::m();
+}
+
+namespace test4 {
+  template <class T> struct A { static void foo(); };
+
+  class B {
+    template <class T> friend void A<T>::foo();
+    B();
+  };
+
+  template <class T> void A<T>::foo() {
+    B b;
+  }
+
+  unsigned test() {
+    A<int>::foo();
+  }
+}
+
+namespace PR8505 {
+// Hits an assertion due to bogus instantiation of class B.
+template <int i> class A {
+  class B* g;
+};
+class B {
+  void f () {}
+};
+// Should not instantiate class B since it is introduced in namespace scope.
+// CHECK2-NOT: _ZN6PR85051AILi0EE1B1fEv
+template class A<0>;
+}
+
+// Ensure that when instantiating initializers for static data members to
+// complete their type in an unevaluated context, we *do* emit initializers with
+// side-effects, but *don't* emit initializers and variables which are otherwise
+// unused in the program.
+namespace PR10001 {
+  template <typename T> struct S {
+    static const int arr[];
+    static const int arr2[];
+    static const int x, y;
+    static int f();
+  };
+
+  extern int foo();
+  extern int kBar;
+
+  template <typename T> const int S<T>::arr[] = { 1, 2, foo() }; // possible side effects
+  template <typename T> const int S<T>::arr2[] = { 1, 2, kBar }; // no side effects
+  template <typename T> const int S<T>::x = sizeof(arr) / sizeof(arr[0]);
+  template <typename T> const int S<T>::y = sizeof(arr2) / sizeof(arr2[0]);
+  template <typename T> int S<T>::f() { return x + y; }
+
+  int x = S<int>::f();
+}
+
+// Ensure that definitions are emitted for all friend functions defined within
+// class templates. Order of declaration is extremely important here. Different
+// instantiations of the class happen at different points during the deferred
+// method body parsing and afterward. Those different points of instantiation
+// change the exact form the class template appears to have.
+namespace PR10666 {
+  template <int N> struct S {
+    void f1() { S<1> s; }
+    friend void g1(S s) {}
+    friend void h1(S s);
+    void f2() { S<2> s; }
+    friend void g2(S s) {}
+    friend void h2(S s);
+    void f3() { S<3> s; }
+  };
+  void test(S<1> s1, S<2> s2, S<3> s3) {
+    g1(s1); g1(s2); g1(s3);
+    g2(s1); g2(s2); g2(s3);
+    h1(s1); h1(s2); h1(s3);
+    h2(s1); h2(s2); h2(s3);
+  }
+}