From: Wolfgang Bangerth <bangerth@math.tamu.edu>
Date: Tue, 24 Sep 2013 18:12:47 +0000 (+0000)
Subject: Work around a change in PETSc 3.4.
X-Git-Tag: v8.1.0~735
X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2be0c6386ffea2a5f240fa75e12635c29918a859;p=dealii.git

Work around a change in PETSc 3.4.

git-svn-id: https://svn.dealii.org/trunk@30916 0785d39b-7218-0410-832d-ea1e28bc413d
---

diff --git a/deal.II/source/lac/petsc_matrix_base.cc b/deal.II/source/lac/petsc_matrix_base.cc
index fb96b311eb..81780da99d 100644
--- a/deal.II/source/lac/petsc_matrix_base.cc
+++ b/deal.II/source/lac/petsc_matrix_base.cc
@@ -358,13 +358,16 @@ namespace PETScWrappers
     ierr = MatGetRow(*this, row, &ncols, &colnums, &values);
     AssertThrow (ierr == 0, MatrixBase::ExcPETScError(ierr));
 
-    // then restore the matrix and return the
-    // number of columns in this row as
-    // queried previously
+    // then restore the matrix and return the number of columns in this row as
+    // queried previously. Starting with PETSc 3.4, MatRestoreRow actually
+    // resets the last three arguments to zero/NULL, to avoid abuse of pointers
+    // now dangling. as a consequence, we need to save the size of the array
+    // and return the saved value.
+    const PetscInt ncols_saved = ncols;
     ierr = MatRestoreRow(*this, row, &ncols, &colnums, &values);
     AssertThrow (ierr == 0, MatrixBase::ExcPETScError(ierr));
 
-    return ncols;
+    return ncols_saved;
   }