lebedev.ri added inline comments.
================
Comment at: test/clang-tidy/readability-function-size.cpp:207-212
+void variables_8() {
+ int a, b;
+ struct A {
+ A(int c, int d);
+ };
+}
----------------
aaron.ballman wrote:
> lebedev.ri wrote:
> > aaron.ballman wrote:
> > > lebedev.ri wrote:
> > > > aaron.ballman wrote:
> > > > > lebedev.ri wrote:
> > > > > > aaron.ballman wrote:
> > > > > > > I think the current behavior here is correct and the previous
> > > > > > > behavior was incorrect. However, it brings up an interesting
> > > > > > > question about what to do here:
> > > > > > > ```
> > > > > > > void f() {
> > > > > > > struct S {
> > > > > > > void bar() {
> > > > > > > int a, b;
> > > > > > > }
> > > > > > > };
> > > > > > > }
> > > > > > > ```
> > > > > > > Does `f()` contain zero variables or two? I would contend that it
> > > > > > > has no variables because S::bar() is a different scope than f().
> > > > > > > But I can see a case being made about the complexity of f() being
> > > > > > > increased by the presence of the local class definition. Perhaps
> > > > > > > this is a different facet of the test about number of types?
> > > > > > As previously briefly discussed in IRC, i **strongly** believe that
> > > > > > the current behavior is correct, and `readability-function-size`
> > > > > > should analyze/diagnose the function as a whole, including all
> > > > > > sub-classes/sub-functions.
> > > > > Do you know of any coding standards related to this check that weigh
> > > > > in on this?
> > > > >
> > > > > What do you think about this:
> > > > > ```
> > > > > #define SWAP(x, y) ({__typeof__(x) temp = x; x = y; y = x;})
> > > > >
> > > > > void f() {
> > > > > int a = 10, b = 12;
> > > > > SWAP(a, b);
> > > > > }
> > > > > ```
> > > > > Does f() have two variables or three? Should presence of the `SWAP`
> > > > > macro cause this code to be more complex due to having too many
> > > > > variables?
> > > > Datapoint: the doc
> > > > (`docs/clang-tidy/checks/readability-function-size.rst`) actually
> > > > already states that macros *are* counted.
> > > >
> > > > ```
> > > > .. option:: StatementThreshold
> > > >
> > > > Flag functions exceeding this number of statements. This may differ
> > > > significantly from the number of lines for macro-heavy code. The
> > > > default is
> > > > `800`.
> > > > ```
> > > > ```
> > > > .. option:: NestingThreshold
> > > >
> > > > Flag compound statements which create next nesting level after
> > > > `NestingThreshold`. This may differ significantly from the expected
> > > > value
> > > > for macro-heavy code. The default is `-1` (ignore the nesting
> > > > level).
> > > > ```
> > > My concerns relate to what's considered a "variable declared in the body"
> > > (per the documentation) in relation to function complexity. To me, if the
> > > variable is not accessible lexically within the body of the function,
> > > it's not adding to the function's complexity *for local variables*. It
> > > may certainly be adding other complexity, of course.
> > >
> > > I would have a very hard time explaining to a user that variables they
> > > cannot see or change (assuming the macro is in a header file out of their
> > > control) contribute to their function's complexity. Similarly, I would
> > > have difficulty explaining that variables in an locally declared class
> > > member function contribute to the number of variables in the outer
> > > function body, but the class data members somehow do not.
> > >
> > > (per the documentation)
> >
> > Please note that the word `complexity` is not used in the
> > **documentation**, only `size` is.
> >
> > There also is the other side of the coin:
> >
> > ```
> > #define simple_macro_please_ignore \
> > the; \
> > actual; \
> > content; \
> > of; \
> > the; \
> > foo();
> >
> > // Very simple function, nothing to see.
> > void foo() {
> > simple_macro_please_ignore();
> > }
> >
> > #undef simple_macro_please_ignore
> > ```
> >
> > In other words, if we ignore macros, it would be possible to abuse them to
> > artificially reduce complexity, by hiding it in the macros.
> > I agree that it's total abuse of macros, but macros are in general not
> > nice, and it would not be good to give such things a pass.
> >
> >
> > > My concerns relate to what's considered a "variable declared in the body"
> > > (per the documentation) in relation to function complexity.
> >
> > Could you please clarify, at this point, your concerns are only about this
> > new part of the check (variables), or for the entire check?
> > In other words, if we ignore macros, it would be possible to abuse them to
> > artificially reduce complexity, by hiding it in the macros.
>
> I don't disagree, that's why I'm trying to explore the boundaries. Your
> example does artificially reduce complexity. My example using swap does not
> -- it's an idiomatic swap macro where the inner variable declaration adds no
> complexity to the calling function as it's not exposed to the calling
> function.
>
> > Could you please clarify, at this point, your concerns are only about this
> > new part of the check (variables), or for the entire check?
>
> Only the new part of the check involving variables.
> > Could you please clarify, at this point, your concerns are only about this
> > new part of the check (variables), or for the entire check?
> Only the new part of the check involving variables.
OK.
This should be split into two boundaries:
* macros
* the nested functions/classes/methods in classes.
I *think* it may make sense to give the latter a pass, no strong opinion here.
But not macros.
(Also, i think it would be good to treat macros consistently within the check.)
Does anyone else has an opinion on how that should be handled?
Repository:
rCTE Clang Tools Extra
https://reviews.llvm.org/D44602
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