structure up into the MPI::Grequest class (rather than being a struct
definition outside of any class) to be similar to how the keyval
intercept data structures are organized. Fix one minor compiler
warning in the process.
This commit was SVN r17171.
(all versions up to and including 20060925). The issue has been
reported to Intel, along with a small [non-MPI] test program that
reproduces the problem (the test program and the OMPI C++ bindings
work fine with Intel C++ 9.0 and many other C++ compilers).
In short, a static initializer for a global variable (i.e., its
constructor is fired before main()) that takes as an argument a
reference to a typedef'd type will simply get the wrong value in the
argument. Specifically:
{{{
namespace MPI {
Intracomm COMM_WORLD(MPI_COMM_WORLD);
}
}}}
The constructor for MPI::Intracomm should get the value of
&ompi_mpi_comm_world. It does not; it seems to get a random value.
As mandated by MPI-2, annex B.13.4, for C/C++ interoperability, the
prototype for this constructor is:
{{{
class Intracomm {
public:
Intracomm(const MPI_Comm& data);
};
}}}
Experiments with icpc 9.1/20060925 have shown that removing the
reference from the prototype makes it work (!). After lots of
discussions about this issue with a C++ expert (Doug Gregor from IU),
we decided the following (cut-n-paste from an e-mail):
-----
> So here's my question: given that OMPI's MPI_<CLASS> types are all
> pointers, is there any legal MPI program that adheres to the above
> bindings that would fail to compile or work properly if we simply
> removed the "&" from the second binding, above?
I don't know of any way that a program could detect this change. FWIW,
the C++ committee has agreed that implementation of the C++ standard
library are allowed to decide arbitrarily between const& and by-value.
If they don't care, MPI users won't care.
When you remove the '&', I suggest also removing the "const". It is
redundant, but can trigger some strange name mangling in Sun's C++
compiler.
-----
So with this change:
* we now work again with the Intel 9.1 compiler
* our C++ bindings do not exactly conform to the MPI-2 spec, but
valid/legal MPI C++ apps cannot tell the difference (i.e., the
functionality is the same)
This commit was SVN r12514.
* Add MPI::Status methods Set_elements() and Set_cancelled()
* Added a bunch of comments in various places in the MPI C++ bindings
implementatio just to explain what's going on (because C++ can hide
a lot from you)
* Insert C++ callbacks for the MPI_Grequest callback functions
registered by MPI::Grequest::Start(). These callbacks keep a
little meta-data (created by Grequest::Start()) that allow the
proper callback signatures from C (i.e., from ompi_grequest_<foo>()
in libmpi.a -- C code), translate arguments as required, and then
invoke the callbacks with proper C++ signatures (i.e., call
user-defined callbacks with C++ function signatures).
This commit was SVN r12446.
The following Trac tickets were found above:
Ticket 580 --> https://svn.open-mpi.org/trac/ompi/ticket/580
