Confusing non-const reference lint from cpplint

[Chris McDonald]

Hello Chromium CXX folks,

While investigating b/206648376 on the Chrome OS side of things I ran into a situation where cpplint.py gives output that doesn't make sense to me: On the file kernel_feature_tool.h cpplint raises the lint 

kernel_feature_tool.h:107:  Is this a non-const reference? If so, make const or use a pointer: KernelFeature& kf  [runtime/references] [2]

but based on my reading of the current style guide a non-optional input/output parameter should be a (non-const) reference.

Am I understanding the style guide correctly here that this reference should be fine? Does this lint show up in Chromium as well or is there potentially a CPPLINT.cfg setting somewhere disabling this lint on the browser side?

Additionally cpplint seems to only raise this lint on the header file and not on kernel_feature_tool.cc, which was also confusing to me. Is this intentional?

I am not a Chromium CXX subject matter expert, so input to help clear up my understanding of what should be happening here is greatly appreciated.

Cheers,

Chris

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[Lei Zhang]

The Google C++ style guide used to disallow non-const references, but
that changed within the last few years. I'm not sure how much
maintenance cpplint.py is getting, but it has not been updated to
match that. In Chromium, https://crrev.com/c/2248714 adjusted "git cl
lint" to drop this check.

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[Joe Mason]

On Wed, Nov 17, 2021 at 6:26 PM 'Chris McDonald' via cxx <c...@chromium.org> wrote:

Additionally cpplint seems to only raise this lint on the header file and not on kernel_feature_tool.cc, which was also confusing to me. Is this intentional?

I'm not 100% sure but this doesn't surprise me - the tool only needs to report the "error" at the function declaration in the header. Reporting it again at the definition in the .cc would be a duplicate.

If there was a function that was *only* referenced in the .cc (like a local helper function in an anonymous namespace) that got skipped by the lint, that would be surprising.