outobj: make a group cumulative

On any other OMF assemblers such as MASM, TASM and ALP, a group is
cumulative.

Signed-off-by: KO Myung-Hun <komh78@gmail.com>

output/outobj.c

@@ -1584,6 +1584,8 @@ obj_directive(enum directive directive, char *value)
             struct Segment *seg;
             struct External **extp;
             int obj_idx;
+            const char *segname;
+            int i;
 
             q = value;
             while (*q == '.')
@@ -1612,11 +1614,11 @@ obj_directive(enum directive directive, char *value)
             for (grp = grphead; grp; grp = grp->next) {
                 obj_idx++;
                 if (!strcmp(grp->name, v)) {
-                    nasm_nonfatal("group `%s' defined twice", v);
+                    break;
-                    return DIRR_ERROR;
                 }
             }
 
+            if (!grp) {
                 *grptail = grp = nasm_malloc(sizeof(*grp));
                 grp->next = NULL;
                 grptail = &grp->next;
@@ -1628,6 +1630,7 @@ obj_directive(enum directive directive, char *value)
                 obj_grp_needs_update = grp;
                 backend_label(v, grp->index + 1, 0L);
                 obj_grp_needs_update = NULL;
+            }
 
             while (*q) {
                 p = q;
@@ -1641,6 +1644,30 @@ obj_directive(enum directive directive, char *value)
                 /*
                  * Now p contains a segment name. Find it.
                  */
+                for (i = 0; i < grp->nentries; i++) {
+                    if (i < grp->nindices) {
+                        segname = NULL;     /* make compiler happy */
+                        for (seg = seghead; seg; seg = seg->next) {
+                            if (grp->segs[i].index == seg->obj_index) {
+                                segname = seg->name;
+                                break;
+                            }
+                        }
+                    }
+                    else
+                        segname = grp->segs[i].name;
+                    /*
+                     * See if this segment is defined in this group.
+                     */
+                    if (!strcmp(segname, p))
+                        break;
+                }
+                if (i < grp->nentries) {
+                    /*
+                     * We have already this segment. Skip.
+                     */
+                    continue;
+                }
                 for (seg = seghead; seg; seg = seg->next)
                     if (!strcmp(seg->name, p))
                         break;