Incorrect size passed to memset while clearing params/resultsBinding vectors

[smradCZ]

In dynamic_prepared_statement.hpp clearing memory of param/result binding vector is not called properly because sizeof(vector) doesn't return size of allocated data but only size of vector instance (24 bytes ~ 3 pointers).

Moreover it seems that all these memset callings could be removed at all because the new values are zero-initialized when vector of PODs (plain old data) is resized (please correct me if I'm wrong).

[danopernis]

You are indeed correct. Third argument to std::memset should be total number of bytes.

As for the second paragraph, standard requires std:resize() to default-insert the values. This is standardese for calling allocator_traits<A>::construct(m, p). Allocator in question is std::allocator, therefore ::new((void *)p) A() is called. Since no arguments to new are provided, after the allocation of memory the value is default-initialized.

If I am not mistaken, after the POD is default-initializated, its value is not specified.

[smradCZ]

Thank you for your reply. As you said ::new((void *)p) A() is called, it means the struct is value-initialized because there are parentheses after the template argument A.

I made some tests (compiled by GCC 7.1 and Clang 3.8 with --std=c++14) proving my theory. Default initialization will be performed in case the ::new((void *)p) A was called (without empty parentheses). Values are not specified in this particular case and they should have any value.

But I'm still not 100% sure about my opinion about that.

I would vote for using std::memset in every other case where the performance is not critical, but the performance is one of the keynotes of this library IMHO.

[danopernis]

I stand corrected, new is called with initializer, albeit empty. Thus value-initialization is indeed performed.