Niels Dekker - address until 2010-10-10 wrote:
Cool! But still I'm concerned about the results from Peter Simons, compiled with g++ 4.4.0 20090526 (prerelease). As that particular version appears to pick boost::swap, instead of std::swap.
The implementation of boost::swap depends on compilers preferring std::swap<T>(T&,T&) over boost::swap<T1,T2>(T1&,T2&), in case of an unqualified swap function call. Thereby, ambiguity is avoided, as was suggested by Steven Watanabe. I really hope this will still work on the latest version of GCC.
Adam and Peter, could you please also test the following on g++ 4.4.0? I really hope it compiles!
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namespace foo // "boost" { template<class T1, class T2> void swap(T1&, T2&) { // Trigger a compile error. int staticAssert[sizeof(T1)!=sizeof(T2)] = {1}; } }
namespace bar // "std" { template<class T> void swap(T&, T&) { return; // okay. }
class string {}; }
int main() { bar::string a1[42]; bar::string a2[42];
using foo::swap; swap(a1, a2); }
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At least, it does compile on g++ 4.1.2, at http://codepad.org/0lyaPrym Kind regards, Niels
Any of gcc-4.4.0, gcc-4.3.4 or gcc-4.2.4 compiles this program. BR, Dmitry