[PATCH] D107900: Add a new clang-tidy check for trivially copyable types passed by const reference

[Christopher Di Bella via Phabricator via cfe-commits]

cjdb added inline comments.


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Comment at: clang-tools-extra/docs/clang-tidy/checks/misc-pod-const-ref-to-value.rst:21
+
+   If set to `true`, this check will limit itself to the `builtinType()` types. Default is `false`.
----------------
jmarrec wrote:
> cjdb wrote:
> > jmarrec wrote:
> > > Quuxplusone wrote:
> > > > D107873 is related.
> > > > 
> > > > I'd like to see some tests/discussion around large types, e.g.
> > > > ```
> > > > struct Widget { int a[1000]; };
> > > > void f(const Widget&);
> > > > ```
> > > > (I think D107873 at least makes a conscious attempt to get the "would it be passed in registers?" check right.)
> > > > 
> > > > I'd like to see some tests/discussion around generic code, e.g.
> > > > ```
> > > > template<class T>
> > > > struct Max {
> > > >     static T max(const T& a, const T& b);
> > > > };
> > > > int x = Max<int>::max(1, 2);  // passes `int` by const reference, but this is fine
> > > > ```
> > > Should I close this one in favor of https://reviews.llvm.org/D107873?
> > Up to you. There's always a chance that D107873 doesn't get approved. What I find most interesting is that we were independently working on this at the same time :-)
> @cjdb I guess it's uncanny that we would both decide to do it at the same time. A bit unfortunate too probably, I could have saved a few hours :) but I learned something about clang-tidy so I don't mind at all!
> 
> Yours (D107873) is definitely better documented, you handle to opposite case (I only deal with const-ref -> value, not value -> const ret) and I just borrowed your implementation for MaxSize / ignoring shared_ptr
> 
> As far as I can tell from a cursory look, there are a couple of things I'm doing that you aren't:
> 
> * I am actually using Options, I don't think you are yet, even for MaxSize. I see from your documentation file that you plan to add a few
> * The RestrictToBuiltInTypes I find an interesting option too
> * I am removing the const as well in addition to the `&`. I guess you are just relying on using it in conjunction with `readability-avoid-const-params-in-decls` but I think that makes it harder to use (you can't just do -checks=-*,<yourcheck> you have to remember to add the readability-avoid-const-params-in-decls too...).
> 
> Perhaps we could discuss adding the above to your PR and consolidate over there to make a nice, feature-complete check?
Sounds good.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D107900/new/

https://reviews.llvm.org/D107900