[cfe-commits] [PATCH] Array exception type decay to pointer automatically

[Richard Smith]

Hi,

On Wed, Nov 21, 2012 at 11:58 PM, WenHan Gu (谷汶翰) <wenhan.gu at gmail.com> wrote:
> Hi Richard,
>
> You're right. I've revised the patch.
> Patch url: http://llvm.org/bugs/attachment.cgi?id=9583
> (Sorry that my environment cannot upload it to GMail)
>
> I didn't put the logic inside CheckSpecifiedExceptionType, since the
> QualType is pass-by-value, instead, I found I should put it before it.
> I also made a test case.

This still needs changes to handle the template instantiation case
(the other caller of CheckSpecifiedExceptionType):

template<typename T> struct S {
  void f() throw(T);
};
S<int[10]> s;

> 2012/11/21 Richard Smith <richard at metafoo.co.uk>
>>
>> On Tue, Nov 20, 2012 at 7:20 PM, WenHan Gu (谷汶翰) <wenhan.gu at gmail.com>
>> wrote:
>> > Hi Richard,
>> > Thanks your comments.
>> >
>> > However, I have no idea whether I should do this patch.
>> > I've tested by gcc, clang and searched C++ spec draft n3242, the result
>> > is
>> > that both GCC and Clang failed on that and I cannot find any wording on
>> > this
>> > issue.
>>
>> I suggest you switch to using n3485.
>>
>> 15.4/2:
>>
>> A type denoted in an exception-specification shall not denote an
>> incomplete type other than a class
>> currently being defined or an rvalue reference type. A type denoted in
>> an exception-specification shall not
>> denote a pointer or reference to an incomplete type, other than cv
>> void* or a pointer or reference to a
>> class currently being defined. A type cv T, “array of T”, or “function
>> returning T” denoted in an exception-
>> specification is adjusted to type T, “pointer to T”, or “pointer to
>> function returning T”, respectively.
>>
>> We are supposed to apply the decay from S[10] to S* before we check
>> whether it's an incomplete-or-being-defined type or a pointer to an
>> incomplete-or-being-defined type, so S[10] is OK.
>>
>> > Could you teach me more or could some else help?
>> > Thanks!
>> >
>> >   1 struct S {
>> >   2   void foo() throw (S[10])  { throw 0; }  // Both gcc and clang
>> > failed
>> > on this function
>> >   3   void bar() throw (S)  { throw 0; }
>> >   4 };
>> >   5
>> >   6 int main() {
>> >   7   S().foo();
>> >   8   S().bar();
>> >   9 }
>> >
>> >
>> >
>> >
>> > 2012/11/21 Richard Smith <richard at metafoo.co.uk>
>> >>
>> >> Hi,
>> >>
>> >> On Tue, Nov 20, 2012 at 1:54 AM, WenHan Gu (谷汶翰) <wenhan.gu at gmail.com>
>> >> wrote:
>> >> > Hi all,
>> >> >
>> >> > I've done the patch and testcase to fix PR14338.
>> >> > http://llvm.org/bugs/show_bug.cgi?id=14388
>> >> >
>> >> > Here's the patch, please review:
>> >> > http://llvm.org/bugs/attachment.cgi?id=9574&action=diff
>> >> >
>> >> >
>> >> > Is that okay to commit?
>> >>
>> >> A matching update is needed in SemaTemplateInstantiateDecl. Perhaps
>> >> you could put this logic into CheckSepcifiedExceptionType (and either
>> >> return the modified type or pass it through by reference)? One of the
>> >> checks in  CheckSpecifiedExceptionType also needs updating. With your
>> >> patch, we still reject this:
>> >>
>> >> struct S {
>> >>   void f() throw (S[10]);
>> >> };
>> >>
>> >> ... but we should accept it, because the type 'S' is supposed to be
>> >> considered as complete in exception specifications inside its body.
>> >
>> >
>> >
>> >
>> > --
>> > Best regards,
>> > Wen-Han Gu (Nowar)
>> >
>
>
>
>
> --
> Best regards,
> Wen-Han Gu (Nowar)
>