[Bug c++/40283] New: [C++0x] Context-specific explicit conversion doesn't work

["piotr dot wyderski at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

std::unique_ptr has an explicit conversion to
bool operator. However, according to Wikipedia:

http://en.wikipedia.org/wiki/C%2B%2B0x#Explicit_conversion_operators

In C++0x, the explicit keyword can now be applied to conversion operators. As
with constructors, it prevents the use of those conversion functions in
implicit conversions. However, language contexts that specifically require a
boolean value (the conditions of if-statements and loops, as well as operands
to the logical operators) count as explicit conversions and can thus use a bool
conversion operator.

But the following code doen't compile:

#include <stdio.h>
#include <memory>

int main(int argc, char *argv[]) {

    std::unique_ptr<int> p(0);

    if (p) {}

    return 0;
}

Results in:

$ gcc -std=gnu++0x testcase.cpp
testcase.cpp: In function 'int main(int, char**)':
testcase.cpp:10: error: could not convert 'p' to 'bool'


-- 
           Summary: [C++0x] Context-specific explicit conversion doesn't
                    work
           Product: gcc
           Version: 4.5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: piotr dot wyderski at gmail dot com
  GCC host triplet: Cygwin/GCC-trunk rev. 147886


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40283