[PATCH] D71980: [clang-tidy] Disable Checks on If constexpr statements in template Instantiations for BugproneBranchClone and ReadabilityBracesAroundStatements

[Gábor Horváth via Phabricator via cfe-commits]

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:
> > 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.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D71980/new/

https://reviews.llvm.org/D71980