Make log here

After some digging, this looks like a clang bug.  First, from the comments on

there seems to be some resistance to the #pragma weak g2 = g3, but since these things work with clang-2.8, that isn't the whole story.  Indeed,

#pragma GCC visibility push(default)

#pragma weak fake = real

#pragma GCC visibility pop

does not expose the symbol "fake".  This must be a bug, but an arguably better way to set up the aliasing is

int fake(int i) __attribute__((weak, alias("real")));

which does work.  I'll report the bug, but maybe Open MPI could use a more complete test for visibility working with weak aliasing?  Or just don't support clang-2.8.

Jed