Fails to compile with "lvalue required as left operand of assignment"

[petwri]

During compiling, I get the following error (Makefile in ./blas/):

lapack_routines.cpp: In function ‘int tridiag(BoostTypedefs::Complex*, int, BoostTypedefs::Complex*, double*, char)’: lapack_routines.cpp:471:60: error: lvalue required as left operand of assignment for(uint i = 0;i<length_diag;i++){diag[i].real() = ndiag[i];diag[i].imag()=0.0;}

Those messages appear multiple times.

I tried different versions of gcc (6, 8), error occurs for all.

[petwri]

Can be closed.
Apparently C++98 standard is applicable here. Compling with g++ --std=gnu++98 works.