go list -e -f '{{range .GoFiles}}{{.}},{{end}}' ./constraint
stdout '^good.go,$'
go list -e -f '{{range .IgnoredGoFiles}}{{.}},{{end}}' ./constraint
stdout '^constraint.go,$'

[cgo] go list -e -f '{{range .XTestGoFiles}}{{.}},{{end}}' ./cgotest
[cgo] stdout '^cgo_test.go,$'

[cgo] go list -e -f '{{range .GoFiles}}{{.}},{{end}}' ./cgoflag
[cgo] stdout '^cgoflag.go,$'

-- go.mod --
module m

go 1.14

	ctxt := build.Default
	pkginfo, err := ctxt.ImportDir(dir, 0)
	if _, nogo := err.(*build.NoGoError); err != nil && !nogo {
		return nil, err
	}

	if *xtestFiles {
		return parseFiles(dir, pkginfo.XTestGoFiles)
	}

	filenames := append(pkginfo.GoFiles, pkginfo.CgoFiles...)
	if *testFiles {
		filenames = append(filenames, pkginfo.TestGoFiles...)
	}
	return parseFiles(dir, filenames)
}

	Imports      []string `yaml:",omitempty"` // import paths used by this package
	TestImports  []string `yaml:",omitempty"` // imports from TestGoFiles
	XTestImports []string `yaml:",omitempty"` // imports from XTestGoFiles
}

// ImportRestriction describes a set of allowable import
// trees for a tree of source code
type ImportRestriction struct {
	// BaseDir is the root of a package tree that is restricted by this