[LLVMbugs] [Bug 12147] New: Unhelpful error message for trying to use an explicit constructor with uniform initialization

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=12147

             Bug #: 12147
           Summary: Unhelpful error message for trying to use an explicit
                    constructor with uniform initialization
           Product: clang
           Version: trunk
          Platform: PC
        OS/Version: All
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: C++0x
        AssignedTo: unassignedclangbugs at nondot.org
        ReportedBy: seth.cantrell at gmail.com
                CC: dgregor at apple.com, llvmbugs at cs.uiuc.edu
    Classification: Unclassified


The code:


    std::unique_ptr<int> j = {new int(0)};


Has a long error message complaining about a bunch of constructors that fail to
match.



error: no matching constructor for initialization of 'std::unique_ptr<int>'
    std::unique_ptr<int> j = {new int(0)};
                         ^   ~~~~~~~~~~~~
../libcxx/include/memory:2535:23: note: candidate constructor (the implicit
copy constructor) not viable: no
      known conversion from 'int *' to 'const std::__1::unique_ptr<int,
std::__1::default_delete<int> > &' for
      1st argument;
class _LIBCPP_VISIBLE unique_ptr
                      ^
../libcxx/include/memory:2564:31: note: candidate constructor not viable: no
known conversion from 'int *' to
      'nullptr_t' for 1st argument;
    _LIBCPP_INLINE_VISIBILITY unique_ptr(nullptr_t) _NOEXCEPT
                              ^
../libcxx/include/memory:2591:31: note: candidate constructor not viable: no
known conversion from 'int *' to
      'std::__1::unique_ptr<int, std::__1::default_delete<int> >' for 1st
argument;
    _LIBCPP_INLINE_VISIBILITY unique_ptr(unique_ptr&& __u) _NOEXCEPT
                              ^
../libcxx/include/memory:2595:9: note: candidate template ignored: failed
template argument deduction
        unique_ptr(unique_ptr<_Up, _Ep>&& __u,
        ^
../libcxx/include/memory:2610:35: note: candidate template ignored: failed
template argument deduction
        _LIBCPP_INLINE_VISIBILITY unique_ptr(auto_ptr<_Up>&& __p,
                                  ^
../libcxx/include/memory:2558:31: note: candidate constructor not viable:
requires 0 arguments, but 1 was
      provided
    _LIBCPP_INLINE_VISIBILITY unique_ptr() _NOEXCEPT
                              ^
../libcxx/include/memory:2578:31: note: candidate constructor not viable:
requires 2 arguments, but 1 was
      provided
    _LIBCPP_INLINE_VISIBILITY unique_ptr(pointer __p, typename conditional<
                              ^
../libcxx/include/memory:2585:31: note: candidate constructor not viable:
requires 2 arguments, but 1 was
      provided
    _LIBCPP_INLINE_VISIBILITY unique_ptr(pointer __p, typename
remove_reference<deleter_type>::type&& __d)
                              ^
1 error generated.

GCC 4.5 has the error message:


prog.cpp: In function 'int main()':
prog.cpp:4:41: error: converting to 'std::unique_ptr<int>' from initializer
list would use explicit constructor 'std::unique_ptr<_Tp,
_Tp_Deleter>::unique_ptr(_Tp*) [with _Tp = int, _Tp_Deleter =
std::default_delete<int>, _Tp* = int*]'


http://ideone.com/h8rgq

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