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  • Linus Torvalds's avatar
    gcc-10: disable 'array-bounds' warning for now · 44720996
    Linus Torvalds authored
    
    
    This is another fine warning, related to the 'zero-length-bounds' one,
    but hitting the same historical code in the kernel.
    
    Because C didn't historically support flexible array members, we have
    code that instead uses a one-sized array, the same way we have cases of
    zero-sized arrays.
    
    The one-sized arrays come from either not wanting to use the gcc
    zero-sized array extension, or from a slight convenience-feature, where
    particularly for strings, the size of the structure now includes the
    allocation for the final NUL character.
    
    So with a "char name[1];" at the end of a structure, you can do things
    like
    
           v = my_malloc(sizeof(struct vendor) + strlen(name));
    
    and avoid the "+1" for the terminator.
    
    Yes, the modern way to do that is with a flexible array, and using
    'offsetof()' instead of 'sizeof()', and adding the "+1" by hand.  That
    also technically gets the size "more correct" in that it avoids any
    alignment (and thus padding) issues, but this is another long-term
    cleanup thing that will not happen for 5.7.
    
    So disable the warning for now, even though it's potentially quite
    useful.  Having a slew of warnings that then hide more urgent new issues
    is not an improvement.
    
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    44720996