[PATCH] D121158: [clang][dataflow] Fix nullptr dereferencing error.

[Yitzhak Mandelbaum via Phabricator via cfe-commits]

ymandel added a comment.

In D121158#3365494 <https://reviews.llvm.org/D121158#3365494>, @ymandel wrote:

> In D121158#3365415 <https://reviews.llvm.org/D121158#3365415>, @xazax.hun wrote:
>
>>> When pre-initializing fields in the environment, the code assumed that all fields of a struct would be initialized
>>
>> Was this assumption ever correct given that it was already skipping the initialization of recursive cases?
>
> Yeah, I had that thought of that and I'm pretty sure it wasn't.  But that does provide a way to test this without creating a very large struct. Let me see if I can add a test to this patch. Otherwise, I'll write a followup.

I added a test for the recursive case and tested (a variant of) it on the code before this patch to verify that it triggered a failure. Interestingly, it triggers a different failure mode in `getChild` -- the assertion that the field will be present. The guard on the recursive case prevents the field from being added at all, so you don't have a nullptr added to the map. But, you also don't have the field added, so the (old) assert would fail. The patch addresses this by allowing for lack of field presence.


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