xazax.hun added inline comments.
================
Comment at: clang-tools-extra/clang-tidy/bugprone/BranchCloneCheck.cpp:62
Finder->addMatcher(
- ifStmt(stmt().bind("if"),
+ ifStmt(unless(allOf(isConstexpr(), isInTemplateInstantiation())),
+ stmt().bind("if"),
----------------
njames93 wrote:
> xazax.hun wrote:
> > njames93 wrote:
> > > xazax.hun wrote:
> > > > Why do we care if we are inside a template instantiation?
> > > >
> > > > Couldn't we trigger the bug with something like:
> > > > ```
> > > > void shouldPass() {
> > > > if constexpr (constexprFun(1) == 0) {
> > > > handle(0);
> > > > } else if constexpr (constexprFun(1) == 1) {
> > > > handle(1);
> > > > } else {
> > > > handle(2);
> > > > }
> > > > }
> > > > ```
> > > >
> > > > ?
> > > We are disabling the bug check when we are in a template instantiation.
> > > Reason being the template instantiation folds away the false branches to
> > > null statements which is the cause of the false positives. Also if there
> > > is a bug in a templated if constexpr, it will be caught when the template
> > > is defined.
> > Yeah, be people are free to write `if constexpr` outside of templates
> > right? So instantiations are not the only places where branches can be
> > folded away.
> The issue is that only template instantiations cause the false branch to get
> folded away, observe [[ https://godbolt.org/z/u48xzy | here ]] to see how its
> handled in templated code that isn't yet instantiated, instantiated template
> code and normal untemplated code
Oh, I see. This is really weird. I do not really see why should the `if
constexpr` behave differently outside of instantiations. Thanks for the
clarification!
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D71980/new/
https://reviews.llvm.org/D71980
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