Riemann is not building on macOS Big Sur

[mandli]

Probably not entirely surprising but I figured I would at least post this as I think at least we can start to gather intel here. Note that this should be only build errors specific to Riemann, not other packages in Clawpack.

[mandli]

This gets thrown when trying to install clawpack in general and just so happens that rp1_acoustics_ptwise is the first recipient of the prize. Interestingly I think that warning about 11.0 might be more problematic than it seems though. Take a look at this discussion on scipy issues as a possible lead. In particular the missing library probably needs to be pointing at 11.0 although I am not sure where it may be getting that.

ERROR: Command errored out with exit status 1:
     command: /usr/local/opt/python@3.9/bin/python3.9 -c 'import sys, setuptools, tokenize; sys.argv[0] = '"'"'/Users/mandli/Dropbox/src/clawpack/setup.py'"'"'; __file__='"'"'/Users/mandli/Dropbox/src/clawpack/setup.py'"'"';f=getattr(tokenize, '"'"'open'"'"', open)(__file__);code=f.read().replace('"'"'\r\n'"'"', '"'"'\n'"'"');f.close();exec(compile(code, __file__, '"'"'exec'"'"'))' develop --no-deps
         cwd: /Users/mandli/Dropbox/src/clawpack/
    Complete output (25 lines):
    gfortran: warning: couldn't understand version 11.0
    gfortran: warning: couldn't understand version 11.0
    gfortran: warning: couldn't understand version 11.0
    gfortran: warning: couldn't understand version 11.0
    gfortran: warning: couldn't understand version 11.0
    gfortran: warning: couldn't understand version 11.0
    gfortran: warning: couldn't understand version 11.0
    gfortran: warning: couldn't understand version 11.0
    gfortran: warning: couldn't understand version 11.0
    gfortran: warning: couldn't understand version 11.0
    riemann/src/rp1_acoustics_ptwise.f90:5:66:

        5 | subroutine rp1_ptwise(num_eqn, num_aux, num_waves, q_l, q_r, aux_l, aux_r,    &
          |                                                                  1
    Warning: Unused dummy argument 'aux_l' at (1) [-Wunused-dummy-argument]
    riemann/src/rp1_acoustics_ptwise.f90:5:73:

        5 | subroutine rp1_ptwise(num_eqn, num_aux, num_waves, q_l, q_r, aux_l, aux_r,    &
          |                                                                         1
    Warning: Unused dummy argument 'aux_r' at (1) [-Wunused-dummy-argument]
    gfortran: warning: couldn't understand version 11.0
    gfortran: warning: couldn't understand version 11.0
    ld: library not found for -lgcc_s.10.4
    collect2: error: ld returned 1 exit status
    error: Command "/usr/local/bin/gfortran -Wall -g -Wall -g -undefined dynamic_lookup -bundle build/temp.macosx-11.0-x86_64-3.9/build/src.macosx-11.0-x86_64-3.9/clawpack/riemann/acoustics_1D_ptwisemodule.o build/temp.macosx-11.0-x86_64-3.9/build/src.macosx-11.0-x86_64-3.9/build/src.macosx-11.0-x86_64-3.9/clawpack/riemann/fortranobject.o build/temp.macosx-11.0-x86_64-3.9/riemann/src/rp1_ptwise.o build/temp.macosx-11.0-x86_64-3.9/riemann/src/rp1_acoustics_ptwise.o build/temp.macosx-11.0-x86_64-3.9/build/src.macosx-11.0-x86_64-3.9/clawpack/riemann/acoustics_1D_ptwise-f2pywrappers.o -L/usr/local/Cellar/gcc/10.2.0/lib/gcc/10/gcc/x86_64-apple-darwin19/10.2.0 -L/usr/local/Cellar/gcc/10.2.0/lib/gcc/10/gcc/x86_64-apple-darwin19/10.2.0/../../.. -L/usr/local/Cellar/gcc/10.2.0/lib/gcc/10/gcc/x86_64-apple-darwin19/10.2.0/../../.. -L/usr/local/lib -L/usr/local/opt/openssl@1.1/lib -L/usr/local/opt/sqlite/lib -lgfortran -o riemann/riemann/acoustics_1D_ptwise.cpython-39-darwin.so" failed with exit status 1
    ----------------------------------------