JonasToth added inline comments.
================
Comment at: test/clang-tidy/cppcoreguidelines-narrowing-conversions.cpp:164
+ while (i) {
+ // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: narrowing conversion from
'int' to 'bool' [cppcoreguidelines-narrowing-conversions]
+ }
----------------
gchatelet wrote:
> JonasToth wrote:
> > lebedev.ri wrote:
> > > courbet wrote:
> > > > What about providing a fix for this one :
> > > > `while (i != 0) {`
> > > Is this //actually// a narrowing conversion as per the CPPCG?
> > > Conversion to bool is a special case, it's not a truncation, but a `x !=
> > > 0`.
> > > I'd think cases like these where bool was pretty clearly meant (`if()`,
> > > `while()`, `for()`, ???) should be exempt.
> > No it is not an narrowing conversion the CPPCG are concerned:
> > https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#es46-avoid-lossy-narrowing-truncating-arithmetic-conversions
> >
> > Short:
> > ```
> > ES.46: Avoid lossy (narrowing, truncating) arithmetic conversions
> >
> > Enforcement
> >
> > A good analyzer can detect all narrowing conversions. However, flagging all
> > narrowing conversions will lead to a lot of false positives. Suggestions:
> >
> > - flag all floating-point to integer conversions (maybe only
> > float->char and double->int. Here be dragons! we need data)
> > - flag all long->char (I suspect int->char is very common. Here be
> > dragons! we need data)
> > - consider narrowing conversions for function arguments especially
> > suspect
> > ```
> >
> > We do have a readability-check that is concerned about int -> bool
> > conversions. Because of that I think we could safely ignore the `int->bool`
> > conversion.
> > But `float -> bool` is still suspicious in my opinion. It has the same
> > semantics, but comparing `float` on equality is dangerous and one could
> > argue it shall be enforced through point 1 (all float-to-int conversions).
> @JonasToth Do you have the name of the readability check so I can document
> the behavior?
Should be
https://clang.llvm.org/extra/clang-tidy/checks/readability-implicit-bool-conversion.html
Repository:
rCTE Clang Tools Extra
https://reviews.llvm.org/D53488
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