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From: "plasmahh at gmx dot net" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/57526] New: use of X before deduction of auto error for seemingly good code
Date: Tue, 04 Jun 2013 15:36:00 -0000
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57526

            Bug ID: 57526
           Summary: use of X before deduction of auto error for seemingly
                    good code
           Product: gcc
           Version: 4.8.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: plasmahh at gmx dot net

Hi,

for the following code

template<class T>
struct A
{
        void bar( ) { }

        void foo( )
        {
                auto* this_ptr = this;
                auto lc = [&]( )
                {
                        this_ptr->bar();
                };
                lc();
        }
};

int main(int argc, const char *argv[])
{
        A<int> a;
        a.foo();
}


I get gcc 4.8.{0,1} error me out with:

auto.cxx:12:4: error: use of 'A<T>::foo() [with T =
int]::__lambda0::__this_ptr' before deduction of 'auto'
                        this_ptr->bar();

which for one was not the case with gcc 4.7. There are two (strange) ways to
make it go away: Either make it be "auto" isntead of "auto*" or make A not
being a template. I also could not find anything in the standard that would
disallow this.