shadowed declaration warnings

[roblatham00]

The STDIO module will throw warnings about shadowed declarations. for example:

In file included from ../../../darshan-runtime/lib/darshan-stdio.c:87:
../../../darshan-runtime/lib/darshan-stdio.c: In function ‘__wrap_fopen’:
../../../darshan-runtime/lib/darshan.h:227:9: warning: declaration of ‘__darshan_disabled’ shadows a previous local [-Wshadow]
  227 |     int __darshan_disabled = darshan_core_disabled_instrumentation()
      |         ^~~~~~~~~~~~~~~~~~
../../../darshan-runtime/lib/darshan-stdio.c:226:5: note: in expansion of macro ‘MAP_OR_FAIL’
  226 |     MAP_OR_FAIL(fileno); \
      |     ^~~~~~~~~~~
../../../darshan-runtime/lib/darshan-stdio.c:327:5: note: in expansion of macro ‘STDIO_RECORD_OPEN’
  327 |     STDIO_RECORD_OPEN(ret, path, tm1, tm2);
      |     ^~~~~~~~~~~~~~~~~
../../../darshan-runtime/lib/darshan.h:227:9: note: shadowed declaration is here
  227 |     int __darshan_disabled = darshan_core_disabled_instrumentation()
      |         ^~~~~~~~~~~~~~~~~~
../../../darshan-runtime/lib/darshan-stdio.c:320:5: note: in expansion of macro ‘MAP_OR_FAIL’
  320 |     MAP_OR_FAIL(fopen);
      |     ^~~~~~~~~~~

MAP_OR_FAIL looks like this:

#define MAP_OR_FAIL(__func) \
    int __darshan_disabled = darshan_core_disabled_instrumentation()

the problem is that STDIO_RECORD_OPEN itself calls MAP_OR_FAIL (but on fileno, not fopen)

[wkliao]

I am also encountering a similar problem.

When adding --enable-apmpi-mod --enable-apmpi-coll-sync to
my configure command line, make yields the following error.

In file included from darshan-apmpi.c:18:
darshan-apmpi.c: In function ‘__wrap_MPI_Barrier’:
../../../darshan/darshan-runtime/lib/darshan.h:227:9: error: redefinition of ‘__darshan_disabled’
     int __darshan_disabled = darshan_core_disabled_instrumentation()
         ^~~~~~~~~~~~~~~~~~
darshan-apmpi.c:32:11: note: in expansion of macro ‘MAP_OR_FAIL’
           MAP_OR_FAIL(PMPI_Barrier);\
           ^~~~~~~~~~~
darshan-apmpi.c:1389:5: note: in expansion of macro ‘TIME_SYNC’
     TIME_SYNC(__real_PMPI_Barrier(comm));
     ^~~~~~~~~

[wkliao]

In file autoperf/apmpi/lib/darshan-apmpi.c, macro MAP_OR_FAIL is
called before every TIME_SYNC and macro TIME_SYNC itself calls
MAP_OR_FAIL when __APMPI_COLL_SYNC is defined, i.e. enabled by
configure option --enable-apmpi-coll-sync.

https://github.com/argonne-lcf/autoperf/blob/8623a0652735785fe87d89514112e43e4f52a78d/apmpi/lib/darshan-apmpi.c#L27-L35

On the other hand, when __APMPI_COLL_SYNC is not defined,
macro TIME_SYNC does not call MAP_OR_FAIL.

If removing that call to MAP_OR_FAIL inside of TIME_SYNC, then
make runs through. However, because autoperf is an external submodule,
how would this problem be fixed in Darshan itself?

[wkliao]

Maybe the above simple hack to darshan-apmpi.c is not the right fix, as
with it Darshan failed at MPI_Init (tested with a small program that contains
just MPI_Init and MPI_Finalize). Below is the gdb stack.

Program terminated with signal SIGSEGV, Segmentation fault.
#0  0x0000000000000000 in ?? ()
(gdb) where
#0  0x0000000000000000 in ?? ()
#1  0x00007f8362019a58 in MPI_Bcast (buffer=0x7ffdff437878, count=1, datatype=1275070526, root=0, 
    comm=-2080374784) at darshan-apmpi.c:1402
#2  0x00007f8361fa797d in darshan_init_mmap_log (core=0x154ad80, jobid=4057677)
    at ../../../darshan/darshan-runtime/lib/darshan-core.c:824
#3  0x00007f8361fa5a7e in darshan_core_initialize (argc=1, argv=0x7ffdff437a98)
    at ../../../darshan/darshan-runtime/lib/darshan-core.c:286
#4  0x00007f8361fa5577 in MPI_Init (argc=0x7ffdff4379bc, argv=0x7ffdff4379b0)
    at ../../../darshan/darshan-runtime/lib/darshan-core-init-finalize.c:43
#5  0x00000000004006a8 in main (argc=1, argv=0x7ffdff437a98) at mpi_bcast.c:8

[wkliao]

Resolved in #1083