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Arc: remove unused allocation from Weak::new() #50357
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😕 Just use
NonNull::dangling()
here.There was a problem hiding this comment.
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That picks a value based on the alignment size of
T
. WhileRawVec
can checkcap
if its pointer is actually null,Weak
doesn't have that. So, to check,dangling
would need to be called each time.It's also not clear to me what having a never-used pointer to
8
, or16
, etc would provide.There was a problem hiding this comment.
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I don't think calling
dangling
every time is a problem.There was a problem hiding this comment.
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It shouldn't be a problem, the value is constant for the input type.
It may avoid memory access errors in debuggers, or avoid tripping unaligned access warnings in tools like Valgrind (if that's a thing).
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In #41064 we changed all dangling pointers to be aligned rather than 1. There is no reason for this case to be different.
dangling()
optimizes to a constant, there is not issue with calling it many times.