[clang] [flang] [flang][driver] Add -fno-fortran-main (link time) option to remove Fortran_main from link line (PR #74139)

[David Truby via cfe-commits]

DavidTruby wrote:

I think this solution is fine, at least in the short term. 

I had a think after reviewing the initial patch and looking at the failure that @tblah showed in #73124; my thoughts are that the “correct” way of doing this would be instead of linking Fortran_main all the time, we could insert a linker directive in the object file containing the program statement. That way we would only link Fortran_main when there is actually a program statement in the Fortran. However that’s more work and would need a bit more thought anyway so we at least need something like this or the revert in the interim.

https://github.com/llvm/llvm-project/pull/74139