Horton

Re: Undefined behavior detected by new clang's ubsan

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: John Naylor <johncnaylorls@gmail.com>
Cc: Alexander Lakhin <exclusion@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2026-01-20T18:52:08Z
Lists: pgsql-hackers 
John Naylor <johncnaylorls@gmail.com> writes:
> I don't think it's great to pass a NULL pointer to a sort, but the
> length could conceivably be zero for future degenerate cases, so we
> could silence the warning by adding "if (n < 2) return;" before the
> for-loop. The advantage of doing that anyway is it allows us to remove
> all four of the "if (d_ > ST_POINTER_STEP)" branches in the recursion
> part. That's better for readability.

+1

			regards, tom lane

Commits

  1. Future-proof sort template against undefined behavior

  2. Fix various instances of undefined behavior