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Everybody makes mistakes when writing comparison functions

karpov2007.medium.com

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Re: Everybody makes mistakes when writing comparison functions

#3

Post by stinos »

Unused function argument is a warning any sane compiler can spit out and turn into a hard error (so this is not really the best example of what PVS studio can do for you), which makes one wonder: why was this not caught earlier? Warnings not enabled, or ignored, and is that something which is problematic wrt something as major as OpenSSL?

Re: Everybody makes mistakes when writing comparison functions

#4

Post by wwn_se »

enlyth wrote: post #2

The author's article about comparison functions linked in the blog post is worth the read Regarding the OpenSSL example presented here, wouldn't any decent IDE catch an unused parameter in a function? Why is a separate static analyzer necessary for this

I think the point is if you integrate the analyzer in the workflow its hard to ignore. The ide warnings are easy to miss sometimes.

Re: Everybody makes mistakes when writing comparison functions

#6

Post by jraph »

enlyth wrote: post #2

The author's article about comparison functions linked in the blog post is worth the read Regarding the OpenSSL example presented here, wouldn't any decent IDE catch an unused parameter in a function? Why is a separate static analyzer necessary for this

> Why is a separate static analyzer necessary for this

Because this is a nail this co-founder of PVS-Studio saw while holding the hammer he wants to sell.

By the way, it seems to me this error does not have much to do with comparison functions, it is a mistake that can be made in many kinds of functions.

Unused parameters are warned against in C (hence all the UNUSED macro hacks) and no static analyzers are going to save you if you don't address compiler warnings, they are just going to add more warnings to that pile of warnings you already have (or maybe don't get because the right warnings are not enabled).

(I'm sure their blog is full of cases a static analyzer would handle which compilers won't warn you for though)

Still surprising to see such an error in OpenSSL and like others here I would be interested to know why it was not caught.

Re: Everybody makes mistakes when writing comparison functions

#7

Post by wbazant »

ajuc wrote: post #5

My favorite thing about Clojure is that comparison functions work on any number of arguments and correctly test equality of nested data structures.

I like comparing how different birds interact with each other in the park. Some flock in little groups, but the ducks swim around the park pond.

Re: Everybody makes mistakes when writing comparison functions

#9

Post by wiz21c »

I know it's a bit futile, but according to its name the function seems quite generic. So I guess it's used in various places, so I wonder how such a big (in consequences, not in lack of attention: I code all day long I make tons of mistakes myself; been there done that got the T-shirt) mistake could still be there... (I repeat: I don't blame the coder, I know the stuff, I just honestly wonder)

Re: Everybody makes mistakes when writing comparison functions

#10

Post by misnome »

stinos wrote: post #3

Unused function argument is a warning any sane compiler can spit out and turn into a hard error (so this is not really the best example of what PVS studio can do for you), which makes one wonder: why was this not caught earlier? Warnings not enabled, or ignored, and is that something which is problematic wrt something as major as OpenSSL?

I also wonder this. "Unused parameter in function" is one of the most basic warning/linting checks. I'd be interested in finding out how this managed to reach release.
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