gl_verify.rs

macro_rules! verify(                                                                                  
    ($e: expr) => ({                                                                                  
        let result = $e;                                                                              
        let error_code = gl::GetError();                                                              
        if error_code != 0 {                                                                          
            let description = match error_code {                                                      
                gl::INVALID_ENUM =>                   "GL_INVALID_ENUM",                              
                gl::INVALID_FRAMEBUFFER_OPERATION =>  "GL_INVALID_FRAMEBUFFER_OPERATION",             
                gl::INVALID_OPERATION =>              "GL_INVALID_OPERATION",                         
                gl::INVALID_VALUE =>                  "GL_INVALID_VALUE",                             
                gl::NO_ERROR =>                       "GL_NO_ERROR",                                  
                gl::OUT_OF_MEMORY =>                  "GL_OUT_OF_MEMORY",                             
                _ => fail!("Bad gl error code: {}", error_code),                                      
            };
            fail!("gl error: {}({})", description, error_code);                                       
        }
        result
    })
)   


/*
Could be autogenerated from 

...
<group name="ErrorCode">
            <enum name="GL_INVALID_ENUM"/>
            <enum name="GL_INVALID_FRAMEBUFFER_OPERATION"/>
            <enum name="GL_INVALID_FRAMEBUFFER_OPERATION_EXT"/>
            <enum name="GL_INVALID_FRAMEBUFFER_OPERATION_OES"/>
            <enum name="GL_INVALID_OPERATION"/>
            <enum name="GL_INVALID_VALUE"/>
            <enum name="GL_NO_ERROR"/>
            <enum name="GL_OUT_OF_MEMORY"/>
            <enum name="GL_STACK_OVERFLOW"/>
            <enum name="GL_STACK_UNDERFLOW"/>
            <enum name="GL_TABLE_TOO_LARGE"/>
            <enum name="GL_TABLE_TOO_LARGE_EXT"/>
            <enum name="GL_TEXTURE_TOO_LARGE_EXT"/>
        </group>
...
in https://github.com/scoopr/khronos-api/blob/master/gl.xml
*/