From: Daniel Arndt <daniel.arndt@iwr.uni-heidelberg.de>
Date: Wed, 18 Jan 2017 10:28:28 +0000 (+0100)
Subject: Allow merging with different lines only if explicitly requested
X-Git-Tag: v8.5.0-rc1~206^2
X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=refs%2Fpull%2F3789%2Fhead;p=dealii.git

Allow merging with different lines only if explicitly requested
---

diff --git a/include/deal.II/lac/constraint_matrix.h b/include/deal.II/lac/constraint_matrix.h
index 3c3e758873..02535c099c 100644
--- a/include/deal.II/lac/constraint_matrix.h
+++ b/include/deal.II/lac/constraint_matrix.h
@@ -360,15 +360,17 @@ public:
    * However, this behavior can be changed by providing a different value for
    * the second argument.
    *
-   * If both this object and the object given as argument are initialized with
-   * an IndexSet object, local_lines is set to the union of these IndexSet
-   * objects.
+   * By default, merging two ConstraintMatrix objects that are initialized
+   * with different IndexSet objects is not allowed.
+   * This behavior can be altered by setting @p allow_different_local_lines
+   * appropriately.
    *
    * Merging a ConstraintMatrix that is initialized with an IndexSet
    * and one that is not initialized with an IndexSet is not yet implemented.
    */
   void merge (const ConstraintMatrix &other_constraints,
-              const MergeConflictBehavior merge_conflict_behavior = no_conflicts_allowed);
+              const MergeConflictBehavior merge_conflict_behavior = no_conflicts_allowed,
+              const bool allow_different_local_lines = false);
 
   /**
    * Shift all entries of this matrix down @p offset rows and over @p offset
diff --git a/source/lac/constraint_matrix.cc b/source/lac/constraint_matrix.cc
index 29f61125cb..f0b0c1cbdf 100644
--- a/source/lac/constraint_matrix.cc
+++ b/source/lac/constraint_matrix.cc
@@ -475,8 +475,15 @@ void ConstraintMatrix::close ()
 
 void
 ConstraintMatrix::merge (const ConstraintMatrix &other_constraints,
-                         const MergeConflictBehavior merge_conflict_behavior)
+                         const MergeConflictBehavior merge_conflict_behavior,
+                         const bool allow_different_local_lines)
 {
+  (void) allow_different_local_lines;
+  Assert(allow_different_local_lines ||
+         local_lines == other_constraints.local_lines,
+         ExcMessage("local_lines for this and the other objects are not the same "
+                    "although allow_different_local_lines is false."));
+
   // store the previous state with respect to sorting
   const bool object_was_sorted = sorted;
   sorted = false;
diff --git a/tests/lac/constraints_merge_10.cc b/tests/lac/constraints_merge_10.cc
index 7d0fc2dec1..48a6fa0d31 100644
--- a/tests/lac/constraints_merge_10.cc
+++ b/tests/lac/constraints_merge_10.cc
@@ -103,7 +103,7 @@ void merge_check ()
 
       // now merge the two and print the
       // results
-      c1.merge (c2);
+      c1.merge (c2, ConstraintMatrix::no_conflicts_allowed, true);
       c1.print(deallog.get_file_stream());
     };
 }