From: Stefano Zampini <stefano.zampini@gmail.com>
Date: Mon, 16 Jan 2023 14:30:59 +0000 (+0300)
Subject: Fix swap for PETSc vector base
X-Git-Tag: v9.5.0-rc1~369^2~2
X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=fa46fb8b44af0d84642502dbfaa1e3f6ee97fa37;p=dealii.git

Fix swap for PETSc vector base
---

diff --git a/source/lac/petsc_vector_base.cc b/source/lac/petsc_vector_base.cc
index 2d28ec1d9d..9282eafc70 100644
--- a/source/lac/petsc_vector_base.cc
+++ b/source/lac/petsc_vector_base.cc
@@ -1021,8 +1021,13 @@ namespace PETScWrappers
   void
   VectorBase::swap(VectorBase &v)
   {
-    const PetscErrorCode ierr = VecSwap(vector, v.vector);
-    AssertThrow(ierr == 0, ExcPETScError(ierr));
+    std::swap(this->vector, v.vector);
+    std::swap(this->ghosted, v.ghosted);
+    std::swap(this->last_action, v.last_action);
+    // missing swap for IndexSet
+    IndexSet t(this->ghost_indices);
+    this->ghost_indices = v.ghost_indices;
+    v.ghost_indices     = t;
   }
 
 
diff --git a/tests/petsc/copy_to_dealvec_block.cc b/tests/petsc/copy_to_dealvec_block.cc
index 2c4803c80b..c6ede99bb4 100644
--- a/tests/petsc/copy_to_dealvec_block.cc
+++ b/tests/petsc/copy_to_dealvec_block.cc
@@ -75,7 +75,23 @@ test()
   Assert(v_one.ghost_elements() == v_one_from_vec.ghost_elements(),
          ExcInternalError());
 
-
+  // Test swap
+  IndexSet local_active_2(numproc * 4);
+  local_active_2.add_range(myid * 4, myid * 4 + 4);
+  PETScWrappers::MPI::Vector vs1(local_active, MPI_COMM_WORLD);
+  PETScWrappers::MPI::Vector vs2(local_active_2,
+                                 local_relevant,
+                                 MPI_COMM_WORLD);
+  vs1.swap(vs2);
+  Assert(vs1.size() == numproc * 4, ExcInternalError());
+  Assert(vs2.size() == numproc * 2, ExcInternalError());
+  Assert(vs1.locally_owned_size() == 4, ExcInternalError());
+  Assert(vs2.locally_owned_size() == 2, ExcInternalError());
+  Assert(vs1.has_ghost_elements() == true, ExcInternalError());
+  Assert(vs2.has_ghost_elements() == false, ExcInternalError());
+  Assert(vs1.ghost_elements() == v_one.ghost_elements(), ExcInternalError());
+
+  // Now BlockVectors
   PETScWrappers::MPI::BlockVector vb, v;
   vb.reinit(2);
   v.reinit(2);
@@ -139,6 +155,13 @@ test()
              ExcInternalError());
     }
 
+  // Test swap
+  auto old_v_vb2 = vb2.petsc_vector();
+  auto old_v_vb  = vb.petsc_vector();
+  vb.swap(vb2);
+  Assert(vb.petsc_vector() == old_v_vb2, ExcInternalError());
+  Assert(vb2.petsc_vector() == old_v_vb, ExcInternalError());
+
   // done
   if (myid == 0)
     deallog << "OK" << std::endl;