g++ compiled as of yesterday afternoon:
Using built-in specs.
Target: i686-linux
Configured with: ../trunk/configure --enable-languages=c,c++ --build=i686-linux
--host=i686-linux --target=i686-linux
--prefix=/g/users/cgd/proj/gcc-trunk/bld/../inst
Thread model: posix
gcc version 4.4.0 20081123 (experimental) (GCC)
rejects the AFAICT-valid code:
#include <bitset>
class C0 {
public:
C0() : b(0) { } // FAILS.
private:
std::bitset<1> b;
};
class C1 {
public:
C1() : b(1) { } // OK!
private:
std::bitset<1> b;
};
void func() {
C0 val0;
C1 val1;
}
(in particular, the 'C0' initialization) with the error:
test.cc: In constructor 'C0::C0()':
test.cc:5: error: call of overloaded 'bitset(int)' is ambiguous
/g/users/cgd/proj/gcc-trunk/inst/bin/../lib/gcc/i686-linux/4.4.0/../../../../include/c++/4.4.0/bitset:808:
note: candidates are: std::bitset<_Nb>::bitset(const char*, char, char) [with
unsigned int _Nb = 1u]
/g/users/cgd/proj/gcc-trunk/inst/bin/../lib/gcc/i686-linux/4.4.0/../../../../include/c++/4.4.0/bitset:744:
note: std::bitset<_Nb>::bitset(long unsigned int) [with
unsigned int _Nb = 1u]
/g/users/cgd/proj/gcc-trunk/inst/bin/../lib/gcc/i686-linux/4.4.0/../../../../include/c++/4.4.0/bitset:652:
note: std::bitset<1u>::bitset(const std::bitset<1u>&)
I'm not completely sure what's going on here, but I'm thinking it's related to
the fact that the 'char*' ctor actually has two default arguments, and 0 is
convertible to a pointer.
This code is accepted by GCC 4.3.2 and the Comeau test drive.
--
Summary: bitset initialization from 0 rejected.
Product: gcc
Version: 4.4.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: cgd at google dot com
GCC build triplet: i686-linux
GCC host triplet: i686-linux
GCC target triplet: i686-linux
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38244
