I discovered this starting from the following example
extern int &foo();
int &m([&]() { m = foo(); return m; }());
This should be also warned too.
From: [email protected] [mailto:[email protected]]
On Behalf Of Richard Smith
Sent: Friday, September 28, 2012 4:15 PM
To: Jordan Rose; Richard Trieu
Cc: llvm cfe
Subject: Re: [cfe-commits] [Patch] Warn about self-init of refs using
parenthesized initializers
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
<[email protected]<mailto:[email protected]>> 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
<[email protected]<mailto:[email protected]>> 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>_______________________________________________
> cfe-commits mailing list
> [email protected]<mailto:[email protected]>
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