# windows executables have the .exe extension and won't overwrite source files
[GOOS:windows] skip

mkdir out
env GOTMPDIR=$PWD/out

grep 'this should still exist' foo.go

! go build
stderr 'already exists and is not an object file'

grep 'this should still exist' foo.go

-- go.mod --
module foo.go

-- foo.go --
package main // this should still exist

func main() {}