That document is not the standard, [conv.bool] says "A prvalue of type std::nullptr_t can be converted to a prvalue of type bool; the resulting value is false."

but N.B. http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#1423

that DR has been discussed by the committee today and it seems the rule will be changed, so suspending

DR 1423 has now reached ready status, 

http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#1423

so this seems like a good reason to consider a compiler change to evaluate potential code breakages.

Here some recommended test-cases that should hold:

1)

bool b1 = nullptr; // Is well-formed today, needs to be ill-formed

2)

bool b2(nullptr); // well-formed today and under 1423

3)

template<class T>
T&& make();

template<class T>
void sink(T);

template<class T1, class T2,
  class = decltype(sink<T2>(make<T1>()))
>
auto f(int) -> char(&)[1];

template<class, class>
auto f(...) -> char(&)[2];

static_assert(sizeof(f<decltype(nullptr), bool>(0)) != 1, "");

Unsuspending then.

Mine.

Author: paolo
Date: Tue Jun  3 17:48:36 2014
New Revision: 211195

URL: http://gcc.gnu.org/viewcvs?rev=211195&root=gcc&view=rev
Log:
gcc/cp
2014-06-03  Paolo Carlini  <paolo.carlini@oracle.com>

	DR 1423
	PR c++/52174
	* call.c (standard_conversion): Convert nullptr to bool only
	in case of direct-initialization.
	(convert_like_real): Provide informative error message.

gcc/testsuite
2014-06-03  Paolo Carlini  <paolo.carlini@oracle.com>

	DR 1423
	PR c++/52174
	* g++.dg/cpp0x/nullptr31.C: New.
	* g++.dg/cpp0x/sfinae-nullptr1.C: Likewise.
	* g++.dg/cpp0x/nullptr17.C: Update.

libstdc++-v3
2014-06-03  Paolo Carlini  <paolo.carlini@oracle.com>

	DR 1423
	PR c++/52174
	* testsuite/20_util/is_assignable/value.cc: Update.

Added:
    trunk/gcc/testsuite/g++.dg/cpp0x/nullptr31.C
    trunk/gcc/testsuite/g++.dg/cpp0x/sfinae-nullptr1.C
Modified:
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/call.c
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/testsuite/g++.dg/cpp0x/nullptr17.C
    trunk/libstdc++-v3/ChangeLog
    trunk/libstdc++-v3/testsuite/20_util/is_assignable/value.cc

Fixed for 4.10.0.