[Bug libstdc++/57403] New: A vector of volatile int doesn't work, but one of volatile void * does

[Bug libstdc++/57403] New: A vector of volatile int doesn't work, but one of volatile void * does

[nmm1 at cam dot ac.uk]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57403

            Bug ID: 57403
           Summary: A vector of volatile int doesn't work, but one of
                    volatile  void * does
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: nmm1 at cam dot ac.uk

In gcc 4.8.0, the following program fails horribly:

#include <vector>

int main () {
    std::vector<volatile int> memory(123);
}

Change the 'int' to void *' and it works.  It fails under OpenSUSE 11.4
and OpenSUSE 12.1, both on AMD 64-bit, and with gcc 4.6.2 as well.  The
messages are:

Test.cpp: In constructor 'std::vector<_Tp, _Alloc>::vector(std::vector<_Tp,
_Alloc>::size_type, const value_type&, const allocator_type&) [with _Tp =
volatile int; _Alloc = std::allocator<volatile int>; std::vector<_Tp,
_Alloc>::size_type = long unsigned int; std::vector<_Tp, _Alloc>::value_type =
volatile int; std::vector<_Tp, _Alloc>::allocator_type =
std::allocator<volatile int>]':
Test.cpp:4:41: error: could not convert '0' from 'int' to 'const volatile
value_type& {aka const volatile int&}'
     std::vector<volatile int> memory(123);
                                         ^
Test.cpp: In function 'int main()':
Test.cpp:4:41: error: invalid initialization of reference of type 'const
volatile value_type& {aka const volatile int&}' from expression of type 'int'
In file included from /home/nmm/GCC/include/c++/4.8.0/vector:65:0,
                 from Test.cpp:1:
/home/nmm/GCC/include/c++/4.8.0/bits/stl_vector.h:296:7: error: in passing
argument 2 of 'std::vector<_Tp, _Alloc>::vector(std::vector<_Tp,
_Alloc>::size_type, const value_type&, const allocator_type&) [with _Tp =
volatile int; _Alloc = std::allocator<volatile int>; std::vector<_Tp,
_Alloc>::size_type = long unsigned int; std::vector<_Tp, _Alloc>::value_type =
volatile int; std::vector<_Tp, _Alloc>::allocator_type =
std::allocator<volatile int>]'
       vector(size_type __n, const value_type& __value = value_type(),
       ^
In file included from
/home/nmm/GCC/include/c++/4.8.0/x86_64-unknown-linux-gnu/bits/c++allocator.h:33:0,
                 from /home/nmm/GCC/include/c++/4.8.0/bits/allocator.h:47,
                 from /home/nmm/GCC/include/c++/4.8.0/vector:62,
                 from Test.cpp:1:
/home/nmm/GCC/include/c++/4.8.0/ext/new_allocator.h: In instantiation of 'void
__gnu_cxx::new_allocator<_Tp>::deallocate(__gnu_cxx::new_allocator<_Tp>::pointer,
__gnu_cxx::new_allocator<_Tp>::size_type) [with _Tp = volatile int;
__gnu_cxx::new_allocator<_Tp>::pointer = volatile int*;
__gnu_cxx::new_allocator<_Tp>::size_type = long unsigned int]':
/home/nmm/GCC/include/c++/4.8.0/bits/stl_vector.h:175:4:   required from 'void
std::_Vector_base<_Tp, _Alloc>::_M_deallocate(std::_Vector_base<_Tp,
_Alloc>::pointer, std::size_t) [with _Tp = volatile int; _Alloc =
std::allocator<volatile int>; std::_Vector_base<_Tp, _Alloc>::pointer =
volatile int*; std::size_t = long unsigned int]'
/home/nmm/GCC/include/c++/4.8.0/bits/stl_vector.h:162:33:   required from
'std::_Vector_base<_Tp, _Alloc>::~_Vector_base() [with _Tp = volatile int;
_Alloc = std::allocator<volatile int>]'
/home/nmm/GCC/include/c++/4.8.0/bits/stl_vector.h:298:23:   required from
'std::vector<_Tp, _Alloc>::vector(std::vector<_Tp, _Alloc>::size_type, const
value_type&, const allocator_type&) [with _Tp = volatile int; _Alloc =
std::allocator<volatile int>; std::vector<_Tp, _Alloc>::size_type = long
unsigned int; std::vector<_Tp, _Alloc>::value_type = volatile int;
std::vector<_Tp, _Alloc>::allocator_type = std::allocator<volatile int>]'
Test.cpp:4:41:   required from here
/home/nmm/GCC/include/c++/4.8.0/ext/new_allocator.h:110:30: error: invalid
conversion from 'volatile void*' to 'void*' [-fpermissive]
       { ::operator delete(__p); }
                              ^
In file included from /home/nmm/GCC/include/c++/4.8.0/ext/new_allocator.h:33:0,
                 from
/home/nmm/GCC/include/c++/4.8.0/x86_64-unknown-linux-gnu/bits/c++allocator.h:33,
                 from /home/nmm/GCC/include/c++/4.8.0/bits/allocator.h:47,
                 from /home/nmm/GCC/include/c++/4.8.0/vector:62,
                 from Test.cpp:1:
/home/nmm/GCC/include/c++/4.8.0/new:97:6: error:   initializing argument 1 of
'void operator delete(void*)' [-fpermissive]
 void operator delete(void*) _GLIBCXX_USE_NOEXCEPT
      ^

[Bug libstdc++/57403] A vector of volatile int doesn't work, but one of volatile void * does

[pinskia at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57403

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Well volatile void * is a pointer to volatile void and the pointer itself does
not have the volatile on it.

I think the only real issue here is the error message.  IIRC allocators do not
(and cannot) support volatile qualified types.

[Bug libstdc++/57403] A vector of volatile int doesn't work, but one of volatile void * does

[nmm1 at cam dot ac.uk]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57403

--- Comment #2 from Nick Maclaren <nmm1 at cam dot ac.uk> ---
On May 24 2013, pinskia at gcc dot gnu.org wrote:

>http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57403
>
> --- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> --- Well 
> volatile void * is a pointer to volatile void and the pointer itself does 
> not have the volatile on it.

Aargh!  Even after all this time, I still fall into that one :-(  Yes,
you are quite right, and I was making a stupid error.

> I think the only real issue here is the error message. IIRC allocators do 
> not (and cannot) support volatile qualified types.

That may well be true, but I can't find any such restriction in the C++
standard.  It would be a great help if the library specification weren't
so ambiguous - in this case, it hinges around the meaning of the word
'type', and the unqualified word is used with at least three meanings
in the standard.

[Bug libstdc++/57403] A vector of volatile int doesn't work, but one of volatile void * does

[glisse at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57403

--- Comment #3 from Marc Glisse <glisse at gcc dot gnu.org> ---
(In reply to Nick Maclaren from comment #2)
> That may well be true, but I can't find any such restriction in the C++
> standard.  It would be a great help if the library specification weren't
> so ambiguous - in this case, it hinges around the meaning of the word
> 'type', and the unqualified word is used with at least three meanings
> in the standard.

C++03 gives the prototype of the constructor:

explicit vector(size_type n, const T& value = T(), const Allocator& =
Allocator());

which shows that it can't work:

typedef volatile int T;
void f () { T const& a = T(); }

For C++11, the prototype changed, it gets harder to follow...

[Bug libstdc++/57403] A vector of volatile int doesn't work, but one of volatile void * does

[daniel.kruegler at googlemail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57403

Daniel Krügler <daniel.kruegler at googlemail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |daniel.kruegler@googlemail.
                   |                            |com

--- Comment #4 from Daniel Krügler <daniel.kruegler at googlemail dot com> ---
(In reply to Nick Maclaren from comment #2)
> That may well be true, but I can't find any such restriction in the C++
> standard.  It would be a great help if the library specification weren't
> so ambiguous - in this case, it hinges around the meaning of the word
> 'type', and the unqualified word is used with at least three meanings
> in the standard.

Actually there is a miss in Table 27, where the variables T, U, and C are
described as

"any non-const object type (3.9)"

This should be corrected to

"any non-const non-volatile object type (3.9)"

I'm submitting an LWG issue for this.
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From: "daniel.kruegler at googlemail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/57406] New: [C++11] function templates don't accept function types with ref-qualifiers as template arguments
Date: Fri, 24 May 2013 21:16:00 -0000
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http://gcc.gnu.org/bugzilla/show_bug.cgi?idW406

            Bug ID: 57406
           Summary: [C++11] function templates don't accept function types
                    with ref-qualifiers as template arguments
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: daniel.kruegler at googlemail dot com

When attempting to update the library test cases that use the test_category
template I stumbled across compiler error that can be traced to the following
compiler test case:

The following code is rejected by gcc 4.9.0 20130519 (experimental) when
compiled with the flags

-std=c++11 -Wall -pedantic

//----------------------------------------
template<class T>
void foo() { }

int main()
{
  foo<void() const>(); // OK
  foo<void() &>(); // Error (line 7)
  foo<void() const &&>(); // Error
}
//----------------------------------------

"main.cpp||In function 'int main()':|
main.cpp|7|error: parse error in template argument list|
main.cpp|7|error: no matching function for call to 'foo()'|
main.cpp|7|note: candidate is:|
main.cpp|2|note: template<class T> void foo()|
main.cpp|2|note:   template argument deduction/substitution failed:|
main.cpp|7|error: template argument 1 is invalid|
main.cpp|8|error: parse error in template argument list|
main.cpp|8|error: no matching function for call to 'foo()'|
main.cpp|8|note: candidate is:|
main.cpp|2|note: template<class T> void foo()|
main.cpp|2|note:   template argument deduction/substitution failed:|
||=== Build finished: 5 errors, 0 warnings (0 minutes, 0 seconds) ===|
"

The code should be accepted, such types are valid as template argument, as
specified by 8.3.5 p6 b5

[Bug libstdc++/57403] A vector of volatile int doesn't work, but one of volatile void * does

[nmm1 at cam dot ac.uk]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57403

--- Comment #5 from Nick Maclaren <nmm1 at cam dot ac.uk> ---
Because of the last comment, I am not going to close this as resolved,
invalid, but please do so if appropriate.

[Bug libstdc++/57403] A vector of volatile int doesn't work, but one of volatile void * does

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=57403

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|---                         |INVALID

--- Comment #6 from Jonathan Wakely <redi at gcc dot gnu.org> ---
The standard containers don't support volatile types.