[PATCH] D11394: Fix warnings about pessimizing return moves for C++11 and higher

[Richard Smith]

On Tue, Jul 21, 2015 at 5:29 PM, Eric Fiselier <eric at efcs.ca> wrote:

> EricWF added a comment.
>
> Thanks for the patch. I ran into this issue the other day and I'm glad to
> see it fixed.
>
> A little rational: The explicit move's are needed in order to "move" a
> `unique_ptr` in C++03. There is a special definition of `std::move` in
> memory at line 3100 that performs some hacks to make `unique_ptr` movable.
> I don't think any other classes benefit from the "explicit move" in C++03.


I don't think that's right. In C++03, unique_ptr has a
unique_ptr(unique_ptr&) constructor. And the C++03 std::move is:

  template<typename T> T &move(T &v) { return v; }

So... the "explicitly moved for C++03" call to std::move in map appears to
also be redundant (and pessimizing) in C++03. In fact, in C++03, std::move
appears to *always* be a no-op.
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