b = append(b, replacement...)
			}
			continue
		}
		invalid = false
		b = append(b, s[i:i+wid]...)
		i += wid
	}
	return b
}

// isSeparator reports whether the rune could mark a word boundary.
// TODO: update when package unicode captures more of the properties.
func isSeparator(r rune) bool {
	// ASCII alphanumerics and underscore are not separators
	if r <= 0x7F {
		switch {

func (f *File) saveRef(n *ast.Expr, context astContext) {
	sel := (*n).(*ast.SelectorExpr)
	// For now, assume that the only instance of capital C is when
	// used as the imported package identifier.
	// The parser should take care of scoping in the future, so
	// that we will be able to distinguish a "top-level C" from a
	// local C.
	if l, ok := sel.X.(*ast.Ident); !ok || l.Name != "C" {
		return
	}
	if context == ctxAssign2 {

		return
	}

	// bail if file is not zip
	if err == ErrFormat {
		return
	}

	// bail here if no Files expected to be tested
	// (there may actually be files in the zip, but we don't care)
	if zt.File == nil {
		return
	}

	if z.Comment != zt.Comment {
		t.Errorf("comment=%q, want %q", z.Comment, zt.Comment)
	}
	if len(z.File) != len(zt.File) {

		// Ignore warnings and random comments, with one
		// exception: newer GCC versions will sometimes emit
		// an error on a macro #define with a note referring
		// to where the expansion occurs. We care about where
		// the expansion occurs, so in that case treat the note
		// as an error.
		isError := strings.Contains(line, ": error:")
		isErrorNote := strings.Contains(line, ": note:") && sawUnmatchedErrors

							for _, id := range spec.Names {
								mark(id)
							}
						case *ast.TypeSpec:
							mark(spec.Name)
						}
					}
				}
				return true // look at specs
			case *ast.FuncDecl:
				if isDeprecated(n.Doc) {
					mark(n.Name)
				}
				return false
			case *ast.TypeSpec:
				if isDeprecated(n.Doc) {
					mark(n.Name)
				}