[cfe-commits] [Patch] Warn about self-init of refs using parenthesized initializers

[Richard Smith]

I don't think the patch is right. My recollection of this class is (though
perhaps Richard Trieu can correct me):

HandleExpr is intended to be called for the expression which is the
top-level initializer of the declaration.
HandleValue is intended to be called for an expression which is "used"
(either directly in the initialization of the result, or as the operand of
an lvalue-to-rvalue conversion).
Visit* are called for all evaluated subexpressions (including ones we don't
consider to be "used").

So... I think that we shouldn't be calling HandleExpr (nor HandleValue)
from VisitParenListExpr, since it doesn't imply a use, in the required
sense. I think the right way to deal with this is to add special cases for
ParenListExpr and InitListExpr to HandleExpr. We also need to decide
whether to warn in these cases:

int n(n); // Warn here, or is this treated like int n = n;?
int n{n}; // Warn here, or is this treated like int n = n;?


FWIW, it looks like we're missing an IgnoreParenCasts call from HandleExpr,
and the IgnoreParenImpCasts call in HandleValue should be IgnoreParenCasts.
We don't currently warn on cases like these, for instance:

int &r = static_cast<int&>(r);

... nor ...

struct S {} s = static_cast<S&>(s);

On Fri, Sep 28, 2012 at 9:18 AM, Jordan Rose <jordan_rose at apple.com> wrote:

> This still doesn't handle C++11 initialization, does it?
>
> void g() {
>         int &a{a};
> }
>
> Jordan
>
>
> On Sep 28, 2012, at 4:05 , Hans Wennborg <hans at chromium.org> wrote:
>
> > Hi,
> >
> > As pointed out in Wei's email [1], Clang currently fails to warn about
> > self-initialized references when using parenthesized initializers:
> >
> >  void f() {
> >    int &a(a);
> >  }
> >
> > The attached patch fixes this. Please take a look.
> >
> > Thanks,
> > Hans
> >
> > [1].
> http://lists.cs.uiuc.edu/pipermail/cfe-dev/2012-September/024582.html
> >
> <ref_self_init_parenthesized_initializers.patch>_______________________________________________
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> > cfe-commits at cs.uiuc.edu
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>
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