Re: [boost] [unordered] Visual C++ 2013 initializer_listoverloadfailure.

Subject: Re: [boost] [unordered] Visual C++ 2013 initializer_listoverloadfailure.
From: Stephan T. Lavavej (stl_at_[hidden])
Date: 2013-11-05 15:12:08

[Daniel James]
> I don't know how to find out about "DevDiv#796414" so I don't know if it's the same issue.

That's our internal database. (I cite bug numbers so if people ask me about them later I can look them up.)

> This is the example from the start of the thread which was confirmed to fail on Visual C++. 

Thanks, that's the same bug. Just in case, I've reduced your example and added it to the bug:

C:\Temp>type purr.cpp
#include <initializer_list>

struct string {
    string(const char *);
    template <typename InIt> string(InIt, InIt);
};

void insert(const string&) { }
void insert(std::initializer_list<string>) { }

int main() {
    insert("a");
    insert({ "b" });
    insert({ "c", "d" });
}

C:\Temp>cl /EHsc /nologo /W4 purr.cpp
purr.cpp
purr.cpp(13) : error C2668: 'insert' : ambiguous call to overloaded function
        purr.cpp(9): could be 'void insert(std::initializer_list<string>)'
        purr.cpp(8): or       'void insert(const string &)'
        while trying to match the argument list '(initializer-list)'
purr.cpp(14) : error C2668: 'insert' : ambiguous call to overloaded function
        purr.cpp(9): could be 'void insert(std::initializer_list<string>)'
        purr.cpp(8): or       'void insert(const string &)'
        while trying to match the argument list '(initializer-list)'

The bit of Standardese that we're not following is N3690 13.3.3.2 [over.ics.rank]/3: "List-initialization sequence L1 is a better conversion sequence than list-initialization sequence L2 if L1 converts to std::initializer_list<X> for some X and L2 does not."

[Glen Fernandes]
> Stephan, I seem to recall providing a slightly similar example that
> you added as repro to DevDiv#532674 when you renamed it "[Milan]
> initializer_list overloading" on 2012/11/29.

Half of that was the same bug (your complex<double> example).

STL