Quote Originally Posted by GClements View Post
Here, the attachment parameter should be GL_DEPTH.

For these queries, the attachment parameter should probably be GL_FRONT_LEFT. GL_FRONT isn't valid here. According to the glGetFramebufferAttachmentParameter reference page:
Thank you for that nice peace of the puzzle. It's probably correct, though I can't try it out. After some googling I found that different gpus may or may not support code like the above. Nvidia is know to be very lenient. And there is no "strict"-mode to enable unfortunately. All you can do is to write perfect code from the beginning or test your code on different hardware.