// unified IR export data decoder.
func readUnifiedPackage(fset *token.FileSet, ctxt *types.Context, imports map[string]*types.Package, input pkgbits.PkgDecoder) *types.Package {
	pr := pkgReader{
		PkgDecoder: input,

		fake: fakeFileSet{
			fset:  fset,
			files: make(map[string]*fileInfo),
		},

		ctxt:    ctxt,
		imports: imports,

		// name (name with subscript).
		tparamIndex: make(map[ident]*types.TypeParam),

		fake: fakeFileSet{
			fset:  fset,
			files: make(map[string]*fileInfo),
		},
	}
	defer p.fake.setLines() // set lines for files in fset

	for i, pt := range predeclared {
		p.typCache[uint64(i)] = pt
	}
	// Special handling for "any", whose representation may be changed by the

pkg go/build, type MultiplePackageError struct, Files []string
pkg go/build, type MultiplePackageError struct, Packages []string

# CL 135110044 go/token: implement PositionFor accessors, Robert Griesemer <******@****.***>
pkg go/token, method (*File) PositionFor(Pos, bool) Position
pkg go/token, method (*FileSet) PositionFor(Pos, bool) Position

func parsePackage(writer io.Writer, pkg *build.Package, userPath string) *Package {
	// include tells parser.ParseDir which files to include.
	// That means the file must be in the build package's GoFiles or CgoFiles
	// list only (no tag-ignored files, tests, swig or other non-Go files).
	include := func(info fs.FileInfo) bool {
		for _, name := range pkg.GoFiles {
			if name == info.Name() {
				return true
			}

	}

	// run the test for all order permutations of the incoming files
	for _, perm := range [][len(sources)]int{
		{0, 1, 2},
		{0, 2, 1},
		{1, 0, 2},
		{1, 2, 0},
		{2, 0, 1},
		{2, 1, 0},
	} {
		// create file order permutation
		files := make([]*ast.File, len(sources))
		for i := range perm {
			files[i] = orig[perm[i]]
		}

		// type-check package with given file order permutation

				outputfiles = outputfiles[1:]
				numInputs := len(flag.Args())
				numOutputs := len(outputfiles)
				if numOutputs != numInputs {
					return fmt.Errorf("number of output files (%d) not equal to number of input files (%d)", numOutputs, numInputs)
				}
				if err := readPackageConfig(*pkgcfg); err != nil {
					return err
				}
				return nil
			} else {
				if *outfilelist != "" {

    assertEquals("gz", Files.getFileExtension("blah.tar.gz"));
    assertEquals("", Files.getFileExtension("/"));
    assertEquals("", Files.getFileExtension("."));
    assertEquals("", Files.getFileExtension(".."));
    assertEquals("", Files.getFileExtension("..."));
    assertEquals("", Files.getFileExtension("blah"));
    assertEquals("", Files.getFileExtension("blah."));
    assertEquals("", Files.getFileExtension(".blah."));

    assertEquals("gz", Files.getFileExtension("blah.tar.gz"));
    assertEquals("", Files.getFileExtension("/"));
    assertEquals("", Files.getFileExtension("."));
    assertEquals("", Files.getFileExtension(".."));
    assertEquals("", Files.getFileExtension("..."));
    assertEquals("", Files.getFileExtension("blah"));
    assertEquals("", Files.getFileExtension("blah."));
    assertEquals("", Files.getFileExtension(".blah."));

 *
 * <p>{@link java.nio.file.Path} users will find similar utilities in {@link MoreFiles} and the
 * JDK's {@link java.nio.file.Files} class.
 *
 * @author Chris Nokleberg
 * @author Colin Decker
 * @since 1.0
 */
@J2ktIncompatible
@GwtIncompatible
@ElementTypesAreNonnullByDefault
public final class Files {

  private Files() {}

  /**

 *
 * <p>{@link java.nio.file.Path} users will find similar utilities in {@link MoreFiles} and the
 * JDK's {@link java.nio.file.Files} class.
 *
 * @author Chris Nokleberg
 * @author Colin Decker
 * @since 1.0
 */
@J2ktIncompatible
@GwtIncompatible
@ElementTypesAreNonnullByDefault
public final class Files {

  private Files() {}

  /**