stderr:
<stdin>:10:26: warning: redundant conformance constraint 'B': 'MatrixImpl' extension Matrix where B == DefaultMatrixImpl<A> {} // Redundant conformance constraint 'B': 'MatrixImpl' <- huh? ^ <stdin>:10:26: note: conformance constraint 'B': 'MatrixImpl' implied here extension Matrix where B == DefaultMatrixImpl<A> {} // Redundant conformance constraint 'B': 'MatrixImpl' <- huh? ^