[Bug c++/54975] New: [C++11] cv-qualifiers of typedef-name are ignored in lambda expression

[ai.azuma at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54975

             Bug #: 54975
           Summary: [C++11] cv-qualifiers of typedef-name are ignored in
                    lambda expression
    Classification: Unclassified
           Product: gcc
           Version: 4.8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: ai.azuma@gmail.com


Created attachment 28485
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=28485
Output of -v option and preprocessed file with GCC 4.8.0 20121014

The following valid code reproduces the problem;

/////////////////////////////
template<typename T>
struct identity
{
  typedef T type;
};

template<typename T>
void f()
{
  typedef typename T::type A;
  int i = 42;
  int const &cri = i;
  int volatile &vri = i;
  [&]() {
    A const &x = cri;    // Problem here
    A volatile &y = vri; // Likewise
  };
}

int main()
{
  f<identity<int> >();
}
/////////////////////////////

In the lambda-expression, initilizations of cv-qualified references are
obviously legal. However, GCC 4.8.0 20121014 complains as follows;

main.cpp: In instantiation of 'f() [with T = identity<int>]::__lambda0':
main.cpp:16:21:   required from 'struct f() [with T =
identity<int>]::__lambda0'
main.cpp:14:3:   required from 'void f() [with T = identity<int>]'
main.cpp:22:21:   required from here
main.cpp:15:18: error: invalid initialization of reference of type
'identity<int>::type& {aka int&}' from expression of type 'const int'
     A const &x = cri;
                  ^
main.cpp:16:21: error: invalid initialization of reference of type
'identity<int>::type& {aka int&}' from expression of type 'volatile int'
     A volatile &y = vri;
                     ^

The error messages look as if there were no cv-qualifiers in the declarators.

Note that GCC 4.7.3 20121013 also fails to compile, but GCC 4.6.4 20121012
compiles successfully.