snprintf: ignore some compiler warnings

Compilers are fairly unhelpful when telling us that it's possible that
an snprintf() may truncate its copy if it can tell at compile time
that the length of the source strings may be longer than the
destination string.  We know!  That's why we're using snprintf()!

Instead of explicitly using opal_snprintf() to get around the warning,
use the gcc compile flag -Wformat-truncation=0 to disable this warning
when in picky mode.

Signed-off-by: Jeff Squyres <jsquyres@cisco.com>

Author: jsquyres

config/opal_setup_cc.m4

@@ -303,6 +303,11 @@ AC_DEFUN([OPAL_SETUP_CC],[
         _OPAL_CHECK_SPECIFIC_CFLAGS(-fno-strict-aliasing, fno_strict_aliasing, int main() { long double x; })
         _OPAL_CHECK_SPECIFIC_CFLAGS(-pedantic, pedantic)
         _OPAL_CHECK_SPECIFIC_CFLAGS(-Wall, Wall)
+
+        # There are some warnings that we specifically do not care
+        # about / do not agree that gcc emits warnings about them.  So
+        # we turn them off.
+        _OPAL_CHECK_SPECIFIC_CFLAGS(-Wformat-truncation=0, format_truncation)
     fi
 
     # Note: Some versions of clang (at least >= 3.5 -- perhaps

ompi/mpi/c/type_create_f90_complex.c

@@ -11,7 +11,7 @@
  * Copyright (c) 2004-2005 The Regents of the University of California.
  *                         All rights reserved.
  * Copyright (c) 2006-2009 Sun Microsystems, Inc.  All rights reserved.
- * Copyright (c) 2008-2018 Cisco Systems, Inc.  All rights reserved
+ * Copyright (c) 2008-2021 Cisco Systems, Inc.  All rights reserved
  * Copyright (c) 2013      Los Alamos National Security, LLC.  All rights
  *                         reserved.
  * Copyright (c) 2015      Research Organization for Information Science
@@ -112,12 +112,8 @@ int MPI_Type_create_f90_complex(int p, int r, MPI_Datatype *newtype)
          */
         datatype->super.flags |= OMPI_DATATYPE_FLAG_PREDEFINED;
         /* Mark the datatype as a special F90 convenience type */
-        // Specifically using opal_snprintf() here (instead of
-        // snprintf()) so that over-eager compilers do not warn us
-        // that we may be truncating the output.  We *know* that the
-        // output may be truncated, and that's ok.
-        opal_snprintf(datatype->name, sizeof(datatype->name),
-                      "COMBINER %s", (*newtype)->name);
+        snprintf(datatype->name, sizeof(datatype->name),
+                 "COMBINER %s", (*newtype)->name);
 
         a_i[0] = &p;
         a_i[1] = &r;

ompi/mpi/c/type_create_f90_integer.c

@@ -11,7 +11,7 @@
  * Copyright (c) 2004-2005 The Regents of the University of California.
  *                         All rights reserved.
  * Copyright (c) 2006-2009 Sun Microsystems, Inc.  All rights reserved.
- * Copyright (c) 2008-2018 Cisco Systems, Inc.  All rights reserved
+ * Copyright (c) 2008-2021 Cisco Systems, Inc.  All rights reserved
  * Copyright (c) 2013      Los Alamos National Security, LLC.  All rights
  *                         reserved.
  * Copyright (c) 2015      Research Organization for Information Science
@@ -104,12 +104,8 @@ int MPI_Type_create_f90_integer(int r, MPI_Datatype *newtype)
          */
         datatype->super.flags |= OMPI_DATATYPE_FLAG_PREDEFINED;
         /* Mark the datatype as a special F90 convenience type */
-        // Specifically using opal_snprintf() here (instead of
-        // snprintf()) so that over-eager compilers do not warn us
-        // that we may be truncating the output.  We *know* that the
-        // output may be truncated, and that's ok.
-        opal_snprintf(datatype->name, sizeof(datatype->name),
-                      "COMBINER %s", (*newtype)->name);
+        snprintf(datatype->name, sizeof(datatype->name),
+                 "COMBINER %s", (*newtype)->name);
 
         a_i[0] = &r;
         ompi_datatype_set_args( datatype, 1, a_i, 0, NULL, 0, NULL, MPI_COMBINER_F90_INTEGER );

ompi/mpi/c/type_create_f90_real.c

@@ -11,7 +11,7 @@
  * Copyright (c) 2004-2005 The Regents of the University of California.
  *                         All rights reserved.
  * Copyright (c) 2006-2009 Sun Microsystems, Inc.  All rights reserved.
- * Copyright (c) 2008-2018 Cisco Systems, Inc.  All rights reserved
+ * Copyright (c) 2008-2021 Cisco Systems, Inc.  All rights reserved
  * Copyright (c) 2013      Los Alamos National Security, LLC.  All rights
  *                         reserved.
  * Copyright (c) 2015      Research Organization for Information Science
@@ -112,12 +112,8 @@ int MPI_Type_create_f90_real(int p, int r, MPI_Datatype *newtype)
          */
         datatype->super.flags |= OMPI_DATATYPE_FLAG_PREDEFINED;
         /* Mark the datatype as a special F90 convenience type */
-        // Specifically using opal_snprintf() here (instead of
-        // snprintf()) so that over-eager compilers do not warn us
-        // that we may be truncating the output.  We *know* that the
-        // output may be truncated, and it's ok.
-        opal_snprintf(datatype->name, sizeof(datatype->name),
-                      "COMBINER %s", (*newtype)->name);
+        snprintf(datatype->name, sizeof(datatype->name),
+                 "COMBINER %s", (*newtype)->name);
 
         ompi_datatype_set_args( datatype, 2, a_i, 0, NULL, 0, NULL, MPI_COMBINER_F90_REAL );