[mpich-devel] Weak symbols, clang, and users compiling with -fvisibility=hidden

Jed Brown jedbrown at mcs.anl.gov
Mon Jan 6 13:59:24 CST 2014

Pavan Balaji <balaji at mcs.anl.gov> writes:
> This attribute is tested in configure before it’s added to mpi.h.in.

Yes, the configure test is incorrect and the resulting usage in MPICH is
broken (does not do what you intend).

> There was some breakage that Ken recently fixed.  Are you using the
> git mpich/master version for this?  

Yes, I'm using the latest 'master'.  I Cc'd Ken and Antonio because they
were author and reviewer on the "fixes" in late November.

> Also, which version of clang is this?

clang-3.3 accepts the code, but then generates calls directly to PMPI
(and if you use -fvisibility=hidden, it generates R_X86_64_PC32 which
fail at link time).  I would have reported this as a bug to clang, but I
tested clang-3.4/clang-master and it does not accept the code at all
(just like gcc).
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