Make mmg2d robust to the case where all triangles have been deleted.

src/mmg2d/analys_2d.c

@@ -54,6 +54,10 @@ int MMG2D_setadj(MMG5_pMesh mesh, int8_t init_cc) {
   int16_t          tag;
   int8_t           i,ii,i1,i2;
 
+  if ( !mesh->nt ) {
+    return 1;
+  }
+
   if ( abs(mesh->info.imprim) > 5  || mesh->info.ddebug )
     fprintf(stdout,"  ** SETTING TOPOLOGY\n");
 

src/mmg2d/hash_2d.c

@@ -29,7 +29,7 @@
  * \param mesh pointer toward the mesh
  * \return 1 if success, 0 if fail
  *
- * Create adjacency relations between the triangles dein the mesh
+ * Create adjacency relations between the triangles in the mesh
  *
  */
 int MMG2D_hashTria(MMG5_pMesh mesh) {
@@ -40,7 +40,7 @@ int MMG2D_hashTria(MMG5_pMesh mesh) {
   unsigned int   key;
 
   if ( mesh->adja )  return 1;
-  if ( !mesh->nt )  return 0;
+  if ( !mesh->nt )  return 1;
 
   /* memory alloc */
   MMG5_SAFE_CALLOC(hcode,mesh->nt+1,MMG5_int,return 0);

src/mmg2d/length_2d.c

@@ -140,6 +140,10 @@ int MMG2D_prilen(MMG5_pMesh mesh,MMG5_pSol sol) {
   ibmax = 0;
   nullEdge = 0;
 
+  if ( !mesh->nt ) {
+    return 0;
+  }
+
   for (k=0; k<9; k++)  hl[k] = 0;
 
   for (k=1; k<=mesh->nt; k++) {

src/mmg2d/quality_2d.c

@@ -187,6 +187,10 @@ int MMG2D_outqua(MMG5_pMesh mesh,MMG5_pSol met) {
   MMG5_int      k,iel,ok,nex;
   static int8_t mmgWarn0;
 
+  if ( !mesh->nt ) {
+    return 1;
+  }
+
   /* Compute triangle quality*/
   for (k=1; k<=mesh->nt; k++) {
     pt = &mesh->tria[k];