proposal: cmd/vet: warn when runtime.AddCleanup closes over the variable with the Cleanup attached

[DanielMorsing]

Proposal Details

If the function passed to runtime.AddCleanup contains a reference to the variable that the cleanup is attached to, then the variable will remain live and the cleanup will never run. A recent CL exhibited this bug and I can see it being a fairly easy mistake to make. Since AddCleanup is a relatively new API addition, I think it makes sense to detect these errors now before they become a problem.

I suggest that vet warn about this problem. I have an implementation for gopls at CL696775 that can be used to evaluate just how helpful this warning would be.

[DanielMorsing]

cc @alandonovan @golang/tools-team

[gabyhelp]

Related Issues

• proposal: cmd/vet: warn for passing invalid arguments to runtime.SetFinalizer #48019 (closed)

_{(Emoji vote if this was helpful or unhelpful; more detailed feedback welcome in this discussion.)}

[prattmic]

cc @mknyszek @golang/runtime