[Bug c++/37806] New: CV-qualifiers on function typedef's are inconsistently accepted depending on typedef scope

[andrew at nelless dot net]

Hi,

First of all this is my first bug report to GNU GCC so please bare with me.

The issue I having is with typedef assisted declarations of class/struct member
functions. It seems to me that cv-qualifiers on function typedef's are treated
inconsistantly depending on the scope of the typedef.

The below code demonstrates the problem: with NS_SCOPE defined the code
compiles fine with "-Wall -Wextra -pedantic" on 4.3.2 but when NS_SCOPE is
undefined, the const qualifier is ignored with "error: ignoring ‘const’
qualifiers added to function type". To me this seems completely inconsistent
and there is no explaination as to why the qualifer is ignored.

---snip---
#include <iostream>

#ifdef NS_SCOPE
typedef void (function_type)(int) const;
#endif

template <typename T>
struct S1
{
    #ifndef NS_SCOPE
    typedef void (function_type)(int) const;
    #endif  
};


struct S2: public S1<int>
{
    virtual function_type f = 0;
};


struct S3: public S2
{
    void 
    f (int i) const
    {
        std::cout << "Hello world: " << i << std::endl;
    }
};


int
main()
{
    S3 s;
    s.f(5);
}
---snip---


I did find a C++ defect report that may be relevent, but to be honest, i'm not 
certain what is going on with regard to the standard here

http://open-std.org/JTC1/SC22/WG21/docs/cwg_defects.html#295

I hope this can be resolved because it will allow for some really groovy
template
generated interfaces.

Visual Studio 2005 (the only other compiler I have to hand) seems to compile
this
code without NS_SCOPE defined, but I'm uncertain how to thoroughly test this
there.


-- 
           Summary: CV-qualifiers on function typedef's are inconsistently
                    accepted depending on typedef scope
           Product: gcc
           Version: 4.3.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: andrew at nelless dot net
  GCC host triplet: x86_64


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37806