Just stumbled upon this while reading the wiki for SDL_RenderGetLogicalSize:

If this function is called on an SDL_Renderer who never had its logical size set by SDL_RenderSetLogicalSize(), this function sets both w and h to 0.

And this isn't entirely true--internally, logical_w and logical_h get set during SDL_SetRenderTarget, too. Should we change SDL_RenderGetLogicalSize to return the dimensions of the current render target if logical_w or logical_h are zero?

(SDL_RenderSetLogicalSize() can force these to zero, even if you've changed it with a render target. So something feels inconsistent in here.)