[PATCH] D72705: [analyzer] Added new checker 'alpha.unix.ErrorReturn'.

Wed Sep 2 02:42:54 PDT 2020

Szelethus added a comment.

In D72705#2241542 <https://reviews.llvm.org/D72705#2241542>, @balazske wrote:

> The summary of this last discussion is that it is not acceptable to have only the simple check for the explicit comparison with a fixed constant. At least not for return types where the "implicit" check (a check that is always true or false for the error return value) is possible, for example the `char*` case.

Indeed, though I think it is okay to keep them in the checker while this is being developed, because it still tests the infrastructure well enough. We should just remember to fine tune the set of functions we're checking before moving out of alpha.

> For functions that return a sort of "handle" (mainly a pointer to a struct that is not normally used with pointer arithmetic) the checker can still be useful.

Agreed. This is true for //some// out-parameters as well.

> Another solution for the problem is if the system calls are modeled in a way that there is always a state split between error end non-error (we will have a path where it is known that the specific variable can be only (for example) `NULL` and this can be detected by other checkers).

@NoQ had a great comment about the dangers of this: D79432#inline-757474 <https://reviews.llvm.org/D79432#inline-757474>. If we still end up wanting to do this, then I agree with @martong, they should be placed in `StdLibraryFunctionsChecker`.

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  https://reviews.llvm.org/D72705/new/

https://reviews.llvm.org/D72705