Making bool explicit

Author: Christos Konstantinos Matzoros

include/osp/graph_implementations/eigen_matrix_adapter/eigen_sparse_iterator.hpp

@@ -78,7 +78,7 @@ class EigenCSRRange {
 
         inline bool operator!=(const Iterator &other) const { return not(*this == other); }
 
-        inline operator bool() const { return it_; }
+        inline explicit operator bool() const { return it_; }
     };
 
     EigenCSRRange(const Graph &graph, EigenIdxType idx) : graph_(graph), index_(idx) {}
@@ -143,7 +143,7 @@ class EigenCSCRange {
 
         inline bool operator!=(const Iterator &other) const { return not(*this == other); }
 
-        inline operator bool() const { return it_; }
+        inline explicit operator bool() const { return it_; }
     };
 
     EigenCSCRange(const Graph &graph, EigenIdxType idx) : graph_(graph), index_(idx) {}