Re: Possible UNINIT bug within man-db gl sources

[Paul Eggert]

On 2024-08-16 07:30, Bruno Haible wrote:
> Copying and then discarding an uninitialized value of integer
> or pointer type (i.e. not a signalling NaN (*)) is not undefined behaviour.

Although that's how typical implementations behave, the C standard says 
that copying from a source variable has undefined behavior if the source 
could have been declared with 'register' (i.e., it's auto and never has 
its address taken). See C23 §6.3.2.1 paragraph 2. Since the code in 
question is copying from such a source, its behavior is technically 
undefined.

I recall running into a similar problem myself, when writing the mcel 
code, though I don't recall the details.

Proposed patch attached. I daresay there's lots of other places that 
would need a similar fix, assuming this one is acceptable.

0001-avltree-list-avoid-undefined-behavior.patch
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