[Bug c++/49418] openmp default(none) in template function

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49418

Jakub Jelinek jakub at gcc dot gnu.org changed:

   What|Removed |Added

 CC||jakub at gcc dot gnu.org,
   ||jason at gcc dot gnu.org

--- Comment #2 from Jakub Jelinek jakub at gcc dot gnu.org 2011-06-21 
13:32:06 UTC ---
The problem seems to be that x has T const type before instantiation, but
int (without const) after instantiation.
The spot where the const is lost is:
type = type_decays_to (type);
TREE_TYPE (r) = type;  
cp_apply_type_quals_to_decl (cp_type_quals (type), r);
Does C++ really mandate stripping the toplevel qualifiers from the PARM_DECLs
here?  It isn't stripped from VAR_DECLs.
OpenMP 2.5/OpenMP 3.0 says that const qualified parameters and variables are
predetermined shared.  While it hopefully changes in some way in OpenMP 3.1
(though, the current 3.1 draft wording is likely to change, as it is backwards
incompatible with default(none)), for older standards the presence/lack of
const
makes a big difference.

[Bug c++/49418] openmp default(none) in template function

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49418

--- Comment #3 from Jakub Jelinek jakub at gcc dot gnu.org 2011-06-21 
13:34:35 UTC ---
Perhaps the top-level quals from the older type could be used, if the standard
doesn't disallow it?  Like, if T const arg is instantiated with T int or const
int, it would be int const arg, while if it is T arg instantiated with int or
const int, it would be int arg.

[Bug c++/49418] openmp default(none) in template function

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49418

--- Comment #4 from Jakub Jelinek jakub at gcc dot gnu.org 2011-06-21 
13:41:19 UTC ---
template typename T
void f (int const x)
{
#pragma omp parallel default(none)
  int y = x;
}

template typename T
void g (int const x)
{
#pragma omp parallel default(none) shared(x)
  int y = x;
}

void h ()
{
  fint (0);
  gint (0);
}

fails the same way, while after removing template typename T and int
the toplevel qualifier stays and it works as expected.
If the current C++ FE behavior is mandated by the standard, i.e. toplevel
qualifiers must be always dropped from function arguments when in templates and
not otherwise, OpenMP C++ support could just ignore TREE_READONLY on PARM_DECLs
in templates or something, but it looks very weird to me.

[Bug c++/49418] openmp default(none) in template function

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49418

Jason Merrill jason at gcc dot gnu.org changed:

   What|Removed |Added

 Status|UNCONFIRMED |ASSIGNED
   Last reconfirmed||2011.06.21 14:35:35
 AssignedTo|unassigned at gcc dot   |jason at gcc dot gnu.org
   |gnu.org |
 Ever Confirmed|0   |1

--- Comment #5 from Jason Merrill jason at gcc dot gnu.org 2011-06-21 
14:35:35 UTC ---
This is a bug, an unintended consequence of the change to type_decays_to.

[Bug c++/49418] openmp default(none) in template function

[gcc-bug at safetymail dot info]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49418

--- Comment #1 from gcc-bug at safetymail dot info 2011-06-15 11:07:12 UTC ---
Created attachment 24534
  -- http://gcc.gnu.org/bugzilla/attachment.cgi?id=24534
test case