Add an assertion for changing num_threads along execution

Author: byjtew

include/graphblas/reference/coordinates.hpp

@@ -97,6 +97,13 @@ namespace grb {
 				/** Per-thread capacity for parallel stack updates. */
 				size_t _buf;
 
+				/** Number of threads for which these coordinates have been initialised. */
+#ifdef _H_GRB_REFERENCE_OMP_COORDINATES
+				const size_t _threads = config::OMP::threads();
+#else
+				const size_t _threads = 1;
+#endif
+
 				/**
 				 * Increments the number of nonzeroes in the current thread-local stack.
 				 *
@@ -294,6 +301,10 @@ namespace grb {
 					// blocks are not managed by this class)
 				}
 
+				size_t requiredThreadsForUpdate() const noexcept {
+					return _threads;
+				}
+
 				/**
 				 * @returns An empty thread-local stack for new nonzeroes.
 				 */

include/graphblas/reference/vector.hpp

@@ -1274,6 +1274,9 @@ namespace grb {
 
 			template< typename D, typename C >
 			inline C & getCoordinates( Vector< D, reference, C > &x ) noexcept {
+#ifdef _H_GRB_REFERENCE_OMP_VECTOR
+				assert( x._coordinates.requiredThreadsForUpdate() == config::OMP::threads() );
+#endif
 				return x._coordinates;
 			}