compilation failed due to argument unused during compilation: '-ffixed-line-length-132' (-ffixed-line-length-132 vs. -Mextend)

[pawosm-arm]

I know that -ffixed-line-length-132 is the gfortran's equivalent of -Mextend, unfortunately, due to gfortran popularity, -ffixed-line-length-132 can be frequently found throughout the codebase in wild. Flang ignores that option which leads to compilation errors whenever lines are too long in fixed-form code:

$ flang -c sgemm_reference.f -o sgemm_reference_mp.o  -fPIC -DPIC -ffixed-line-length-132 -fopenmp -O3
clang-4.0: warning: argument unused during compilation: '-ffixed-line-length-132' [-Wunused-command-line-argument]
F90-S-0023-Syntax error - unbalanced parentheses (sgemm_reference.f: 188)
F90-S-0310-Adjustable array can not have automatic bounds specifiers - a (sgemm_reference.f)
F90-S-0050-Assumed size array, a, is not a dummy argument (sgemm_reference.f)
F90-S-0310-Adjustable array can not have automatic bounds specifiers - b (sgemm_reference.f)
F90-S-0050-Assumed size array, b, is not a dummy argument (sgemm_reference.f)
F90-S-0310-Adjustable array can not have automatic bounds specifiers - c (sgemm_reference.f)
F90-S-0050-Assumed size array, c, is not a dummy argument (sgemm_reference.f)
  0 inform,   0 warnings,   7 severes, 0 fatal for MAIN

This is the more general issue on how much Flang should be able to act as a drop-in replacement for gfortran and therefore accept its command-line syntax.

[janusw]

This is the more general issue on how much Flang should be able to act as a drop-in replacement for gfortran and therefore accept its command-line syntax.

In that context I would argue that it is much less important for flang to replicate gfortran's command-line syntax than it is to replicate gfortran's feature set.

Talking about line length: It seems that flang is still missing an option that is equivalent to gfortran's -ffree-line-length-none (see https://gcc.gnu.org/onlinedocs/gfortran/Fortran-Dialect-Options.html), allowing arbitrary-length lines.

Regarding identical syntax: Any Fortran project that supports more than just one compiler has to define compiler-specific flags anyway, which is really not hard to do (using proper build tools like cmake). The options of gfortran/ifort/pgi/sun differ an awful lot.

Cheers,
Janus