// Identify leading run of // comments and blank lines,
	// which must be followed by a blank line.
	// Also identify any //go:build comments.
	content, goBuild, _, err := parseFileHeader(content)
	if err != nil {
		return false
	}

	// If //go:build line is present, it controls.
	// Otherwise fall back to +build processing.
	var shouldBuild bool
	switch {
	case goBuild != nil:

	// Identify leading run of // comments and blank lines,
	// which must be followed by a blank line.
	// Also identify any //go:build comments.
	content, goBuildBytes, sawBinaryOnly, err := parseFileHeader(content)
	if err != nil {
		return "", nil, false, err
	}

	// If //go:build line is present, it controls, so no need to look for +build .
	// Otherwise, get plusBuild constraints.
	if goBuildBytes == nil {

}

// parseFileHeader should be an internal detail,
// but widely used packages access it using linkname.
// Notable members of the hall of shame include:
//   - github.com/bazelbuild/bazel-gazelle
//
// Do not remove or change the type signature.
// See go.dev/issue/67401.
//
//go:linkname parseFileHeader