https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79933
--- Comment #3 from PeteVine <tulipawn at gmail dot com> --- In gcc 8, -std=f2003 is required to overcome the issue but there's another failure later on: gfortran -c -O2 -std=f2003 solverinterface.f90 solverinterface.f90:108:9: real*4 fpar(16) ! hint by Shibo 1 Error: GNU Extension: Nonstandard type declaration REAL*4 at (1) solverinterface.f90:153:7: fpar(1) = RTOL(VarSC) 1 Error: Unclassifiable statement at (1) solverinterface.f90:154:7: fpar(2) = ATOL(VarSC) 1 Error: Unclassifiable statement at (1) solverinterface.f90:156:7: fpar(1) = RTOL(ivar) ! relative tolerance, must be between (0, 1) 1 Error: Unclassifiable statement at (1) solverinterface.f90:157:7: fpar(2) = ATOL(ivar) ! absolute tolerance, must be positive 1 Error: Unclassifiable statement at (1) solverinterface.f90:176:1: NNZ, Alu,Jlu,Ju,Jw ) 1 Are there any gfortran switches that would enable compiling this code base as is?