Fix for YOJIMBO_NEW() null pointer dereference.

[sherief]

YOJIMBO_DECLARE_MESSAGE_TYPE() expands to:

message = YOJIMBO_NEW( allocator, msg_action );
    if ( !message )
        return NULL;

But YOJIMBO_NEW() never checks the result from Allocate(), it just immediately passes it to placement new(), which dereferences a null pointer if Allocate() fails. This makes it impossible to gracefully handle OOM situations, and leads to unpreventable crashes.

This change replaces the existing macro with a short lambda evaluated on the spot that checks for the null pointer and avoids placement new in OOM situations.

[sherief]

The macOS build is failing but I think this should be fixable by updating the C++ standard used by clang++ while compiling (and I doubt any shipping and supported macOS / iOS product won't support this lambda), but I'm a bit lost in the build files and I don't have a Mac to test on - if you'd point me to where to make the changes I'll update the pull request.

Thanks a lot Glenn!

[gafferongames]

Hi, I'd really like to keep the C++ standard compatible with older versions. I don't want to require Modern C++ to use yojimbo. Can somebody please apply a fix that works with older versions of C++ standard?

[sherief]

No worries, just let me know what version of the C++ standard you want to target and I'll investigate the best way to provide a fix that's in line with that requirement.

[gafferongames]

C++ 03

[grahamreeds]

Really? Are there any build targets that don't support C++11? Even the embedded compilers I use - which are notoriously slow at updating their standards - support 11 now.

GR

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C++ 03

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[gafferongames]

My man, I don't like Modern C++