[libc-commits] [libc] [libc] Expand usage of libc null checks. (PR #116262)

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lntue wrote:

> @lntue the unit tests are generating failures here that I don't understand. I'm not sure if this should've been merged. They generated errors that are also affecting all other PRs.
> 
> I traced back the errors and they only occur on this PR , and not #142085
> 
> Failure in question :
> 
> ```
> [6320/6668] Running unit test libc.test.src.string.memcmp_opt_host_test.__unit__
> FAILED: projects/libc/test/src/string/CMakeFiles/libc.test.src.string.memcmp_opt_host_test.__unit__ /home/gha/actions-runner/_work/llvm-project/llvm-project/build/projects/libc/test/src/string/CMakeFiles/libc.test.src.string.memcmp_opt_host_test.__unit__ 
> ```

`bzero` and `bcmp` tests also failed in the precommit CI for similar errors (Illegal instructions on SizeSweep tests).  Those 2 are not related to your change at all.  Also post commit CIs are happy with the change, and right now I cannot reproduce these failures locally.  It's probably for other reasons than this change.

https://github.com/llvm/llvm-project/pull/116262