Re: [C++0x] nullptr

[Magnus Fromreide <magfr at lysator dot liu dot se>]

On Thu, 2010-06-03 at 02:06 +0100, Jonathan Wakely wrote:
> On 30 May 2010 11:32, Paolo Carlini wrote:
> > ... oops, as a matter of fact you can as well directly define in
> > c++config std::nullptr_t, instead of std::__nullptr_t, in complete
> > analogy with the other stddef typedefs and be done with it. Sorry, I was
> > following a previous version of my ideas ;)
> 
> I've done that but am working on applying the other library changes -
> the shared_ptr parts needed some work and I'm getting an ICE and
> errors about not being able to convert nullptr_t to int*, which seems
> wrong.  I'm still trying to reduce the problem or figure out what I'm
> doing wrong.
> 
> Will update soon ...

It looks as if the nullptr code is buggy.

With the attached patch it seems to work.

/MF

Index: gcc/testsuite/g++.dg/cpp0x/nullptr22.C
===================================================================
--- gcc/testsuite/g++.dg/cpp0x/nullptr22.C	(revision 160252)
+++ gcc/testsuite/g++.dg/cpp0x/nullptr22.C	(working copy)
@@ -13,4 +13,8 @@
   f2(nullptr); // { dg-warning "null argument where non-null required " }
   f3("x", "y", __null); // { dg-warning "missing sentinel in function call" }
   f3("x", "y", nullptr);
+  decltype(nullptr) mynull = 0;
+  f1("%p", mynull);
+  f2(mynull); // { dg-warning "null argument where non-null required " }
+  f3("x", "y", mynull);
 }
Index: gcc/testsuite/g++.dg/cpp0x/nullptr05.C
===================================================================
--- gcc/testsuite/g++.dg/cpp0x/nullptr05.C	(revision 160252)
+++ gcc/testsuite/g++.dg/cpp0x/nullptr05.C	(working copy)
@@ -10,3 +10,5 @@
 const pmf pmf1 = nullptr;
 const pmf pmf2 = __null;
 const pmf pmf3 = 0;
+decltype(nullptr) mynull = 0;
+const pmf pmf4 = mynull;
Index: gcc/testsuite/g++.dg/cpp0x/nullptr14.C
===================================================================
--- gcc/testsuite/g++.dg/cpp0x/nullptr14.C	(revision 160252)
+++ gcc/testsuite/g++.dg/cpp0x/nullptr14.C	(working copy)
@@ -20,4 +20,6 @@
   //
   type_equal<char*>(f(nullptr));
   type_equal<int>(f(0));
+  decltype(nullptr) mynull = 0;
+  type_equal<char*>(f(mynull));
 }
Index: gcc/testsuite/g++.dg/cpp0x/nullptr06.C
===================================================================
--- gcc/testsuite/g++.dg/cpp0x/nullptr06.C	(revision 160252)
+++ gcc/testsuite/g++.dg/cpp0x/nullptr06.C	(working copy)
@@ -10,4 +10,6 @@
 void fun()
 {
   assert_true(cp1 == nullptr);
+  decltype(nullptr) mynull = 0;
+  assert_true(cp1 == mynull);
 }
Index: gcc/testsuite/g++.dg/cpp0x/nullptr15.C
===================================================================
--- gcc/testsuite/g++.dg/cpp0x/nullptr15.C	(revision 160252)
+++ gcc/testsuite/g++.dg/cpp0x/nullptr15.C	(working copy)
@@ -18,4 +18,7 @@
   //
   g(nullptr);               // { dg-error "no matching function for call to " }
   type_equal<float*>(g((float*)nullptr));
+  decltype(nullptr) mynull = 0;
+  g(mynull);                // { dg-error "no matching function for call to " }
+  type_equal<float*>(g((float*)mynull));
 }
Index: gcc/testsuite/g++.dg/cpp0x/nullptr07.C
===================================================================
--- gcc/testsuite/g++.dg/cpp0x/nullptr07.C	(revision 160252)
+++ gcc/testsuite/g++.dg/cpp0x/nullptr07.C	(working copy)
@@ -9,4 +9,7 @@
   if( n == nullptr ); // { dg-error "invalid operands of types " }
   const int m = 1;
   if( m == nullptr ); // { dg-error "invalid operands of types " }
+  decltype(nullptr) mynull = 0;
+  if( n == mynull ); // { dg-error "invalid operands of types " }
+  if( m == mynull ); // { dg-error "invalid operands of types " }
 }
Index: gcc/testsuite/g++.dg/cpp0x/nullptr16.C
===================================================================
--- gcc/testsuite/g++.dg/cpp0x/nullptr16.C	(revision 160252)
+++ gcc/testsuite/g++.dg/cpp0x/nullptr16.C	(working copy)
@@ -19,4 +19,7 @@
   type_equal<int>(h(0));
   type_equal<nullptr_t>(h(nullptr));
   type_equal<float*>(h((float*)nullptr));
+  nullptr_t mynull = 0;
+  type_equal<nullptr_t>(h(mynull));
+  type_equal<float*>(h((float*)mynull));
 }
Index: gcc/testsuite/g++.dg/cpp0x/nullptr08.C
===================================================================
--- gcc/testsuite/g++.dg/cpp0x/nullptr08.C	(revision 160252)
+++ gcc/testsuite/g++.dg/cpp0x/nullptr08.C	(working copy)
@@ -8,4 +8,6 @@
 void fun()
 {
   assert_true(nullptr ? false : true);
+  decltype(nullptr) mynull = 0;
+  assert_true(mynull ? false : true);
 }
Index: gcc/testsuite/g++.dg/cpp0x/nullptr17.C
===================================================================
--- gcc/testsuite/g++.dg/cpp0x/nullptr17.C	(revision 160252)
+++ gcc/testsuite/g++.dg/cpp0x/nullptr17.C	(working copy)
@@ -18,4 +18,6 @@
 {
   // Overload to bool, not int
   type_equal<bool>(i(nullptr));
+  decltype(nullptr) mynull = 0;
+  type_equal<bool>(i(mynull));
 }
Index: gcc/testsuite/g++.dg/cpp0x/nullptr01.C
===================================================================
--- gcc/testsuite/g++.dg/cpp0x/nullptr01.C	(revision 160252)
+++ gcc/testsuite/g++.dg/cpp0x/nullptr01.C	(working copy)
@@ -6,3 +6,5 @@
 char* const cp1 = nullptr;
 char* const cp2 = __null;
 char* const cp3 = 0;
+decltype(nullptr) mynull = 0;
+char* const cp4 = mynull;
Index: gcc/testsuite/g++.dg/cpp0x/nullptr09.C
===================================================================
--- gcc/testsuite/g++.dg/cpp0x/nullptr09.C	(revision 160252)
+++ gcc/testsuite/g++.dg/cpp0x/nullptr09.C	(working copy)
@@ -6,4 +6,6 @@
 void fun()
 {
   if( nullptr == 0 );
+  decltype(nullptr) mynull = 0;
+  if( mynull == 0 );
 }
Index: gcc/testsuite/g++.dg/cpp0x/nullptr10.C
===================================================================
--- gcc/testsuite/g++.dg/cpp0x/nullptr10.C	(revision 160252)
+++ gcc/testsuite/g++.dg/cpp0x/nullptr10.C	(working copy)
@@ -7,4 +7,8 @@
 {
   nullptr = 0;         // { dg-error "lvalue required as left operand" }
   nullptr + 2;         // { dg-error "invalid operands of types " }
+  decltype(nullptr) mynull = 0;
+  mynull = 1;          // { dg-error "cannot convert" }
+  mynull = 0;
+  mynull + 2;          // { dg-error "invalid operands of types " }
 }
Index: gcc/testsuite/g++.dg/cpp0x/nullptr18.C
===================================================================
--- gcc/testsuite/g++.dg/cpp0x/nullptr18.C	(revision 160252)
+++ gcc/testsuite/g++.dg/cpp0x/nullptr18.C	(working copy)
@@ -16,4 +16,6 @@
 void test_j()
 {
   type_equal<char*>(j(nullptr));
+  decltype(nullptr) mynull = 0;
+  type_equal<char*>(j(mynull));
 }
Index: gcc/testsuite/g++.dg/cpp0x/nullptr02.C
===================================================================
--- gcc/testsuite/g++.dg/cpp0x/nullptr02.C	(revision 160252)
+++ gcc/testsuite/g++.dg/cpp0x/nullptr02.C	(working copy)
@@ -8,3 +8,9 @@
 const nullptr_t np1 = nullptr;
 const nullptr_t np2 = __null;
 const nullptr_t np3 = 0;
+const nullptr_t np4 = np1;
+const nullptr_t np5 = np2;
+const nullptr_t np6 = np3;
+const nullptr_t np7 = np4;
+const nullptr_t np8 = np5;
+const nullptr_t np9 = np6;
Index: gcc/testsuite/g++.dg/cpp0x/nullptr11.C
===================================================================
--- gcc/testsuite/g++.dg/cpp0x/nullptr11.C	(revision 160252)
+++ gcc/testsuite/g++.dg/cpp0x/nullptr11.C	(working copy)
@@ -14,4 +14,27 @@
   assert_false(nullptr > nullptr);
   assert_true(nullptr <= nullptr);
   assert_true(nullptr >= nullptr);
+
+  decltype(nullptr) mynull = 0;
+
+  assert_true(mynull == nullptr);
+  assert_false(mynull != nullptr);
+  assert_false(mynull < nullptr);
+  assert_false(mynull > nullptr);
+  assert_true(mynull <= nullptr);
+  assert_true(mynull >= nullptr);
+
+  assert_true(nullptr == mynull);
+  assert_false(nullptr != mynull);
+  assert_false(nullptr < mynull);
+  assert_false(nullptr > mynull);
+  assert_true(nullptr <= mynull);
+  assert_true(nullptr >= mynull);
+
+  assert_true(mynull == mynull);
+  assert_false(mynull != mynull);
+  assert_false(mynull < mynull);
+  assert_false(mynull > mynull);
+  assert_true(mynull <= mynull);
+  assert_true(mynull >= mynull);
 }
Index: gcc/testsuite/g++.dg/cpp0x/nullptr20.C
===================================================================
--- gcc/testsuite/g++.dg/cpp0x/nullptr20.C	(revision 160252)
+++ gcc/testsuite/g++.dg/cpp0x/nullptr20.C	(working copy)
@@ -10,8 +10,11 @@
 {
   char buf1[64];
   char buf2[64];
+  char buf3[64];
 
   std::sprintf(buf1, "%p", (void*)0);
   std::sprintf(buf2, "%p", nullptr);
-  return std::strcmp(buf1, buf2) != 0;
+  decltype(nullptr) mynull = 0;
+  std::sprintf(buf3, "%p", nullptr);
+  return std::strcmp(buf1, buf2) != 0 || std::strcmp(buf1, buf3) != 0;
 }
Index: gcc/testsuite/g++.dg/cpp0x/nullptr03.C
===================================================================
--- gcc/testsuite/g++.dg/cpp0x/nullptr03.C	(revision 160252)
+++ gcc/testsuite/g++.dg/cpp0x/nullptr03.C	(working copy)
@@ -3,4 +3,7 @@
 
 // Test assignment to int
 
-const int n = nullptr;     // { dg-error "cannot convert " }
+const int n1 = nullptr;     // { dg-error "cannot convert " }
+decltype(nullptr) mynull = 0;
+const int n2 = mynull;      // { dg-error "cannot convert " }
+
Index: gcc/testsuite/g++.dg/cpp0x/nullptr12.C
===================================================================
--- gcc/testsuite/g++.dg/cpp0x/nullptr12.C	(revision 160252)
+++ gcc/testsuite/g++.dg/cpp0x/nullptr12.C	(working copy)
@@ -4,3 +4,5 @@
 // Test sizeof
 
 static_assert(sizeof(nullptr) == sizeof(void*), "sizeof(nullptr) is wrong");
+const decltype(nullptr) mynull = 0;
+static_assert(sizeof(mynull) == sizeof(void*), "sizeof(nullptr) is wrong");
Index: gcc/testsuite/g++.dg/cpp0x/nullptr21.C
===================================================================
--- gcc/testsuite/g++.dg/cpp0x/nullptr21.C	(revision 160252)
+++ gcc/testsuite/g++.dg/cpp0x/nullptr21.C	(working copy)
@@ -24,4 +24,21 @@
   } catch (...) {
     printf("Test 1 Fail");
   }  // { dg-output "Test 1 OK" }
+
+  nullptr_t mynull = 0;
+  try {
+    throw mynull;
+  } catch (void*) {
+    printf("Test 2 Fail");
+  } catch (bool) {
+    printf("Test 2 Fail");
+  } catch (int) {
+    printf("Test 2 Fail");
+  } catch (long int) {
+    printf("Test 2 Fail");
+  } catch (nullptr_t) {
+    printf("Test 2 OK");
+  } catch (...) {
+    printf("Test 2 Fail");
+  }  // { dg-output "Test 2 OK" }
 }
Index: gcc/testsuite/g++.dg/cpp0x/nullptr04.C
===================================================================
--- gcc/testsuite/g++.dg/cpp0x/nullptr04.C	(revision 160252)
+++ gcc/testsuite/g++.dg/cpp0x/nullptr04.C	(working copy)
@@ -11,3 +11,9 @@
 const short int n5 = reinterpret_cast<short int>(nullptr); // { dg-error "loses precision" }
 const ssize_t n6 = reinterpret_cast<ssize_t>(nullptr);
 const ssize_t n7 = (ssize_t)nullptr;
+
+decltype(nullptr) mynull = 0;
+const int n8 = static_cast<const int>(mynull); // { dg-error "invalid static_cast " }
+const short int n9 = reinterpret_cast<short int>(mynull); // { dg-error "loses precision" }
+const ssize_t n10 = reinterpret_cast<ssize_t>(mynull);
+const ssize_t n11 = (ssize_t)mynull;
Index: gcc/testsuite/g++.dg/cpp0x/nullptr13.C
===================================================================
--- gcc/testsuite/g++.dg/cpp0x/nullptr13.C	(revision 160252)
+++ gcc/testsuite/g++.dg/cpp0x/nullptr13.C	(working copy)
@@ -5,7 +5,12 @@
 
 #include <typeinfo>
 
+#define assert_true(b) do { char c[2 * bool(b) - 1]; } while(0)
+
 void fun()
 {
   typeid(nullptr);
+  const decltype(nullptr) mynull = 0;
+  typeid(mynull);
+  assert_true(typeid(nullptr) == typeid(mynull));
 }
Index: gcc/cp/typeck.c
===================================================================
--- gcc/cp/typeck.c	(revision 160252)
+++ gcc/cp/typeck.c	(working copy)
@@ -7019,7 +7019,7 @@
     }
 
   /* Handle null pointer to member function conversions.  */
-  if (integer_zerop (pfn))
+  if (null_ptr_cst_p (pfn))
     {
       pfn = build_c_cast (input_location, type, integer_zero_node);
       return build_ptrmemfunc1 (to_type,
Index: gcc/cp/cvt.c
===================================================================
--- gcc/cp/cvt.c	(revision 160252)
+++ gcc/cp/cvt.c	(working copy)
@@ -196,7 +196,7 @@
       return error_mark_node;
     }
 
-  if (integer_zerop (expr))
+  if (null_ptr_cst_p (expr))
     {
       if (TYPE_PTRMEMFUNC_P (type))
 	return build_ptrmemfunc (TYPE_PTRMEMFUNC_FN_TYPE (type), expr, 0,