[Bug c++/20453] New: GCC fails to treat a valid constant expression as a template argument

[Bug c++/20453] New: GCC fails to treat a valid constant expression as a template argument

[joaquin at tid dot es]

This is happening in the compilation of boost::aligned_storage
(boost/aligned_storage.hpp) in the current CVS. 
The version of GCC used is 4.0.0 20050309 (prerelease)

I am sorry I can't provide a verified to fail snippet,
since I don't have access to that version of GCC. The
following is an untested attempt to reproduce the
problem in isolated code.

#include <cstddef>

template <
     std::size_t size_
   , std::size_t alignment_ = std::size_t(-1)
class aligned_storage
{
};

int main()
{
  aligned_storage<1> as;
}

This produces the following:

'(size_t)((-1))' is not a valid template argument for type 'unsigned int' 
because it is a non-constant expression

which AFAICS is an invalid error.

-- 
           Summary: GCC fails to treat a valid constant expression as a
                    template argument
           Product: gcc
           Version: 4.0.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: joaquin at tid dot es
                CC: gcc-bugs at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20453

[Bug c++/20453] GCC fails to treat a valid constant expression as a template argument

[falk at debian dot org]

------- Additional Comments From falk at debian dot org  2005-03-13 13:42 -------
(In reply to comment #0)

> I am sorry I can't provide a verified to fail snippet,
> since I don't have access to that version of GCC. The
> following is an untested attempt to reproduce the
> problem in isolated code.

I cannot reproduce the error with this code. Please provide a working test
case.


-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |WAITING


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20453

[Bug c++/20453] GCC fails to treat a valid constant expression as a template argument

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-03-13 14:30 -------
I cannot reproduce it either with an obvious change to fix the missing >:
#include <cstddef>

template <
     std::size_t size_
   , std::size_t alignment_ = std::size_t(-1)>
class aligned_storage
{
};

int main()
{
  aligned_storage<1> as;
}

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20453

[Bug c++/20453] GCC fails to treat a valid constant expression as a template argument

[joaquin at tid dot es]

------- Additional Comments From joaquin at tid dot es  2005-03-13 15:05 -------
(In reply to comment #2)
> I cannot reproduce it either with an obvious change to fix the missing

Too bad. Sorry for reporting this in such an imprecise
manner. The actual problem shows at Boost regression tests

http://tinyurl.com/4hxy5

I'll try to isolate it into a snippet amenable to study,
as soon as I find someone with access to that version of
the compiler

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20453

[Bug c++/20453] GCC fails to treat a valid constant expression as a template argument

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-03-13 15:09 -------
(In reply to comment #3)
> (In reply to comment #2)
> > I cannot reproduce it either with an obvious change to fix the missing
> 
> Too bad. Sorry for reporting this in such an imprecise
> manner. The actual problem shows at Boost regression tests
> 
> http://tinyurl.com/4hxy5

Maybe this already been fixed.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20453

[Bug c++/20453] GCC fails to treat a valid constant expression as a template argument

[joaquin at tid dot es]

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------- Additional Comments From joaquin at tid dot es  2005-03-14 17:08 -------
(In reply to comment #4)
> (In reply to comment #3)
> > (In reply to comment #2)
> > > I cannot reproduce it either with an obvious change to fix the missing
> > 
> > Too bad. Sorry for reporting this in such an imprecise
> > manner. The actual problem shows at Boost regression tests
> > 

OK, I've got a test case:

#include <cstddef>

template<
 std::size_t size_,
 std::size_t alignment_ = std::size_t(-1)>
struct aligned_storage
{
};

template<typename T>
struct foo
{
  aligned_storage<sizeof(T)> as;
};

int main()
{
  foo<double> f;
}

Fails with the following:

13: error: '(size_t)((-1))' is not a valid template argument for type 'unsigned 
int' because it is a non-constant expression

Regards,

Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20453

[Bug c++/20453] [4.0/4.1 Regression] GCC fails to treat a valid constant expression as a template argument

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-03-14 17:11 -------
Confirmed, this worked with 4.0.0 20050225 which means it started to fail after the branch.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |pinskia at gcc dot gnu dot
                   |                            |org
           Severity|normal                      |critical
             Status|WAITING                     |NEW
     Ever Confirmed|                            |1
           Keywords|                            |rejects-valid
   Last reconfirmed|0000-00-00 00:00:00         |2005-03-14 17:11:31
               date|                            |
            Summary|GCC fails to treat a valid  |[4.0/4.1 Regression] GCC
                   |constant expression as a    |fails to treat a valid
                   |template argument           |constant expression as a
                   |                            |template argument
   Target Milestone|---                         |4.0.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20453

[Bug c++/20453] [4.0/4.1 Regression] GCC fails to treat a valid constant expression as a template argument

[nathan at gcc dot gnu dot org]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |nathan at gcc dot gnu dot
                   |dot org                     |org
             Status|NEW                         |ASSIGNED
   Last reconfirmed|2005-03-14 17:11:31         |2005-03-17 14:53:18
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20453

[Bug c++/20453] [4.1 Regression] GCC fails to treat a valid constant expression as a template argument

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-03-17 15:36 -------
(In reply to comment #6)
> Confirmed, this worked with 4.0.0 20050225 which means it started to fail after the branch.
Also it worked with the mainline with 20050306.
And also on the 4.0 branch, but it is still broken on the mainline.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[4.0/4.1 Regression] GCC    |[4.1 Regression] GCC fails
                   |fails to treat a valid      |to treat a valid constant
                   |constant expression as a    |expression as a template
                   |template argument           |argument
   Target Milestone|4.0.0                       |4.1.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20453

[Bug c++/20453] [4.1 Regression] GCC fails to treat a valid constant expression as a template argument

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-03-17 16:09 -------
This is also fixed on the mainline.
It was fixed by:
2005-03-17  Nathan Sidwell  <nathan@codesourcery.com>

        PR c++/20186
        * pt.c (contains_dependent_cast_p): Remove.
        (fold_non_dependent_expr): Don't use it.
        (value_dependent_expression_p): Use a switch statement.
        reference_exprs can be dependent.


-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20453