aaron.ballman 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);
+ };
+}
----------------
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.
Repository:
rCTE Clang Tools Extra
https://reviews.llvm.org/D44602
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