cmd/vet: know what builtin functions have no side effects #22851
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Change https://golang.org/cl/97775 mentions this issue: |
Change https://golang.org/cl/112177 mentions this issue: |
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That was the intention with the existing code, but it was buggy; builtin functions aren't treated as values by types.TypeAndVal. Thus, we should use the IsBuiltin method instead of IsValue. Teaching vet what builtin funcs are pure is already being tracked as a separate issue, #22851. While at it, also add a test with methods, just to be sure that the current logic doesn't break with that edge case either. Fixes #25303. Change-Id: Ic18402b22cceeabf76641c02f575b194b9a536cc Reviewed-on: https://go-review.googlesource.com/112177 Run-TryBot: Daniel Martí <mvdan@mvdan.cc> Run-TryBot: Robert Griesemer <gri@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Robert Griesemer <gri@golang.org>
I've abandoned the CL I had sent for this, since it required more work and it had gotten considerable merge conflicts. Perhaps someone else will pick up this issue in the future. |
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Reminder issue to continue the work in https://go-review.googlesource.com/c/go/+/79536.
For example,
len
andcap
never have any side effects, and it would be useful to know thati == len(x) || i == len(x)
is a suspicious expression.More broadly, this could be extended to automatically detect what functions are free of side effects. But this would require having access to the full source with full type information, and may be complex and costly, so I'm not entirely sure it's a right fit for vet.
A simpler version of the above would be to also add standard library functions, such as
strings.Contains
orpath.Join
. I don't know if it is OK for vet to treat standard library packages differently, though.The text was updated successfully, but these errors were encountered: