golang 1.20.14 + w64devkit-x64-2.4.0
$ export GOROOT=D:/develop/golang/go
$ export PATH=D:/develop/mingw64-w64devkit/bin:$GOROOT/bin:$PATH;
$ go build cgo.go
# command-line-arguments
cgo: cannot parse gcc output $WORK\b001\\_cgo_.o as ELF, Mach-O, PE, XCOFF object
cgo.go:
package main
/*
#include <stdio.h>
void say_hello() {
    printf("Hello from C!\n");
}
*/
import "C"
import "fmt"
func main() {
	fmt.Println("Going to call C code...")
	C.say_hello()
	fmt.Println("C code finished.")
}