Sven patch to check the optimized description before freeing it. For predefined

datatypes the optimized description point to the default description, so special
care should be taken before freeing it.

This commit was SVN r10119.

ompi/datatype/dt_module.c

@@ -281,11 +281,16 @@ int ompi_ddt_local_sizes[DT_MAX_PREDEFINED];
         (PDST)->id       = (PSRC)->id;                                  \
         (PDST)->nbElems  = (PSRC)->nbElems;                             \
         (PDST)->bdt_used = (PSRC)->bdt_used;                            \
-        if( (PDST)->desc.desc != NULL )                                 \
+        if( NULL != (PDST)->desc.desc )                                 \
             free( (PDST)->desc.desc );                                  \
-        (PDST)->desc     = (PSRC)->desc;                                \
-        if( (PDST)->opt_desc.desc != NULL )                             \
+        /* Don't re-assing the (PDST)->desc because we need the pointer \
+         * value in the following if statement. In the case of          \
+         * predefined datatypes both descriptors point to the same      \
+         * memory and if we free the memory twice bad things happen.*/  \
+        if( (NULL != (PDST)->opt_desc.desc) &&                          \
+            ((PDST)->opt_desc.desc != (PDST)->desc.desc) )              \
             free( (PDST)->opt_desc.desc );                              \
+        (PDST)->desc     = (PSRC)->desc;                                \
         (PDST)->opt_desc = (PSRC)->opt_desc;                            \
         (PDST)->packed_description = (PSRC)->packed_description;        \
         (PSRC)->packed_description = NULL;                              \