decltype support

[MathieuDutSik]

The following code does not compile:

---

#include <sparsehash/dense_hash_map>
#include
int main(int argc, char* argv[])
{
auto hash_fct=[&](size_t eVal) -> size_t {
return std::hash<size_t>()(eVal % 128);
};
auto equal_fct=[&](size_t eVal1, size_t eVal2) -> bool {
return eVal1 == eVal2;
};
google::dense_hash_map<size_t, size_t, decltype(hash_fct), decltype(equal_fct)> V({}, hash_fct, equal_fct);
for (size_t i=0; i<10; i++) {
size_t& group = V[i];
}
}

---

Error is no matching function for call to ‘swap( for both the hash and equality functions.

Replacing "google::dense_hash_map" by "std::unordered_map" makes the code compiles.

As it happen this is only annoying, not blocking. The "solution" is to std::function<size_t(size_t)> hash_fct instead of auto hash_fct. Also, replace decltype(hash_fct) by std::function<size_t(size_t)>. Of course do similarly for the equality test.

But that is annoying and maybe there is a better solution.