[bugfix] Avoid using non-official implementation details of DUNE_THROW

When throwing a `MatrixBlockError` the `DUNE_THROW` macro was
abused to also set the data members of `MatrixBlockError` by
referring e.g. to the local (in macro) variable name `th__ex`.
I consider this a bug, since these are undocumented implementation
details. Furthermore their use prohibits any change to `DUNE_THROW`
e.g. to make it `constexpr` friendly.

dune/istl/dilu.hh

@@ -9,6 +9,7 @@
 #include <complex>
 #include <map>
 #include <vector>
+#include <sstream>
 
 #include <dune/common/fmatrix.hh>
 #include <dune/common/scalarvectorview.hh>
@@ -81,9 +82,13 @@ namespace Dune
         }
         catch (Dune::FMatrixError &e)
         {
-          DUNE_THROW(MatrixBlockError, "DILU failed to invert matrix block D[" << row_i << "]"
-                                                                               << e.what();
-                     th__ex.r = row_i;);
+          std::ostringstream sstream;
+          sstream << THROWSPEC(MatrixBlockError)
+            << "DILU failed to invert matrix block D[" << row_i << "]" << e.what();
+          MatrixBlockError ex;
+          ex.message(sstream.str());
+          ex.r = row_i;
+          throw ex;
         }
       }
     }

dune/istl/ildl.hh

@@ -3,6 +3,8 @@
 #ifndef DUNE_ISTL_ILDL_HH
 #define DUNE_ISTL_ILDL_HH
 
+#include <sstream>
+
 #include <dune/common/scalarvectorview.hh>
 #include <dune/common/scalarmatrixview.hh>
 #include "ilu.hh"
@@ -135,7 +137,14 @@ namespace Dune
       }
       catch( const Dune::FMatrixError &e )
       {
-        DUNE_THROW( MatrixBlockError, "ILDL failed to invert matrix block A[" << i.index() << "][" << ij.index() << "]" << e.what(); th__ex.r = i.index(); th__ex.c = ij.index() );
+        std::ostringstream sstream;
+        sstream << THROWSPEC(MatrixBlockError)
+          << "ILDL failed to invert matrix block A[" << i.index() << "][" << ij.index() << "]" << e.what();
+        MatrixBlockError ex;
+        ex.message(sstream.str());
+          ex.r = i.index();
+          ex.c = ij.index();
+        throw ex;
       }
     }
   }

dune/istl/ilu.hh

@@ -5,6 +5,8 @@
 #ifndef DUNE_ISTL_ILU_HH
 #define DUNE_ISTL_ILU_HH
 
+#include <sstream>
+
 #include <cmath>
 #include <complex>
 #include <map>
@@ -82,9 +84,16 @@ namespace Dune {
           Impl::asMatrix(*ij).invert();   // compute inverse of diagonal block
         }
         catch (Dune::FMatrixError & e) {
-          DUNE_THROW(MatrixBlockError, "ILU failed to invert matrix block A["
-                     << i.index() << "][" << ij.index() << "]" << e.what();
-                     th__ex.r=i.index(); th__ex.c=ij.index(););
+          std::ostringstream sstream;
+          sstream << THROWSPEC(MatrixBlockError)
+            << THROWSPEC(MatrixBlockError)
+            << "ILU failed to invert matrix block A["
+            << i.index() << "][" << ij.index() << "]" << e.what();
+          MatrixBlockError ex;
+          ex.message(sstream.str());
+          ex.r = i.index();
+          ex.c = ij.index();
+          throw ex;
         }
       }
     }