wrapping fortran in go on macOS: ld: library not found for -lgfortran

I am wrapping a fortran program in a go wrapper for modernizing scientific models, as a prerequisite this works on Windows. I got a mac and am curious on how to make it run on the M2 chip. here is what I have done so far on my mac:

• installed gcc and gfortran through brew
• built it through go build ./cmd/fort
• added the // #cgo LDFLAGS: -v per the cgo documentation

here is a repo with the work I have so far:

• https://github.com/marty-farce/fort

I get the error when I use -v in the ldflags configuration

# github.com/marty-farce/fort/cmd/fort
/opt/homebrew/Cellar/go/1.20.6/libexec/pkg/tool/darwin_arm64/link: running cc failed: exit status 1
Apple clang version 14.0.3 (clang-1403.0.22.14.1)
Target: arm64-apple-darwin22.5.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin
 "/Library/Developer/CommandLineTools/usr/bin/ld" -demangle -lto_library /Library/Developer/CommandLineTools/usr/lib/libLTO.dylib -dynamic -arch arm64 -platform_version macos 13.0.0 13.3 -syslibroot /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk -o $WORK/b001/exe/a.out -L/usr/local/lib -headerpad 1144 /var/folders/w1/nf_07l0x6xq6t9yx9wdz9vlw0000gn/T/go-link-2078530619/go.o /var/folders/w1/nf_07l0x6xq6t9yx9wdz9vlw0000gn/T/go-link-2078530619/000000.o /var/folders/w1/nf_07l0x6xq6t9yx9wdz9vlw0000gn/T/go-link-2078530619/000001.o /var/folders/w1/nf_07l0x6xq6t9yx9wdz9vlw0000gn/T/go-link-2078530619/000002.o /var/folders/w1/nf_07l0x6xq6t9yx9wdz9vlw0000gn/T/go-link-2078530619/000003.o /var/folders/w1/nf_07l0x6xq6t9yx9wdz9vlw0000gn/T/go-link-2078530619/000004.o /var/folders/w1/nf_07l0x6xq6t9yx9wdz9vlw0000gn/T/go-link-2078530619/000005.o /var/folders/w1/nf_07l0x6xq6t9yx9wdz9vlw0000gn/T/go-link-2078530619/000006.o /var/folders/w1/nf_07l0x6xq6t9yx9wdz9vlw0000gn/T/go-link-2078530619/000007.o /var/folders/w1/nf_07l0x6xq6t9yx9wdz9vlw0000gn/T/go-link-2078530619/000008.o /var/folders/w1/nf_07l0x6xq6t9yx9wdz9vlw0000gn/T/go-link-2078530619/000009.o /var/folders/w1/nf_07l0x6xq6t9yx9wdz9vlw0000gn/T/go-link-2078530619/000010.o /var/folders/w1/nf_07l0x6xq6t9yx9wdz9vlw0000gn/T/go-link-2078530619/000011.o /var/folders/w1/nf_07l0x6xq6t9yx9wdz9vlw0000gn/T/go-link-2078530619/000012.o
-lgfortran -framework CoreFoundation -lSystem /Library/Developer/CommandLineTools/usr/lib/clang/14.0.3/lib/darwin/libclang_rt.osx.a
ld: library not found for -lgfortran
clang: error: linker command failed with exit code 1 (use -v to see invocation)

the main thing is the linker cannot find the library for gfortran, despite looking for "-lgfortran", I suspect I am not including the library properly. I tried messing with the cgo LDFLAGS variable to include the location of the gfortran binary making the LDFLAGS variable line look like this

// #cgo LDFLAGS: -L/opt/homebrew/bin -v

but that didn't change where the linker is looking for the gfortran library, are there any linker people who can help me out?

what you need to do is find the location of your "libgfortran" library, macos has an unconventional file system (I'm new to mac but I come from a linux background), the way I did this is

tree . > ~/Desktop/file

and made a search for 'libgfortran' in that treed file. I got the path "-L/opt/homebrew/lib/gcc/13", put that in the application, and now it builds because it found the library. I added a commit to the repo to show what I mean