An example calling from C to Go to C, tested on Windows with MinGW.
First build the Go archive:
go build -buildmode=c-archive -o hello.a .\main.go
In addition to a static library, hello.a, there should also be a Go-generated C header file, hello.h (included here for reference), which is imported in main.c.
Next, build the C executable:
gcc .\main.c .\hello.a -o hello.exe
Expected output:
Hello from C!
Hello from Go!
Hello from C from Go!