since it is copied into two different C output files, it must not
contain any definitions, only declarations. If a file contains both
definitions and declarations, then the two output files will produce
duplicate symbols and the linker will fail. To avoid this, definitions
must be placed in preambles in other files, or in C source files.

# Passing pointers

Go is a garbage collected language, and the garbage collector needs to

case x == 4: f3()
}
</pre>

<p>
Implementation restriction: A compiler may disallow multiple case
expressions evaluating to the same constant.
For instance, the current compilers disallow duplicate integer,
floating point, or string constants in case expressions.
</p>

<h4 id="Type_switches">Type switches</h4>

<p>
A type switch compares types rather than values. It is otherwise similar

// converts names to upper case, and rewrites _ into Pad_godefs_n,
// so that all fields are exported.
func godefsFields(fld []*ast.Field) {
	prefix := fieldPrefix(fld)

	// Issue 48396: check for duplicate field names.
	if prefix != "" {
		names := make(map[string]bool)
	fldLoop:
		for _, f := range fld {
			for _, n := range f.Names {
				name := n.Name
				if name == "_" {
					continue

	isDup bool
}

type fileInfoDirEntry interface {
	fs.FileInfo
	fs.DirEntry
}

func (f *fileListEntry) stat() (fileInfoDirEntry, error) {
	if f.isDup {
		return nil, errors.New(f.name + ": duplicate entries in zip file")
	}
	if !f.isDir {
		return headerFileInfo{&f.file.FileHeader}, nil
	}
	return f, nil
}

// Only used for directories.

		{"VADDPD.A.A X0, X1, X2", `unknown suffix "A"; duplicate suffix "A"`},
		{"VADDPD.A.A.A X0, X1, X2", `unknown suffix "A"; duplicate suffix "A"`},
		{"VADDPD.A.B X0, X1, X2", `unknown suffix "A"; unknown suffix "B"`},
		{"VADDPD.Z.A X0, X1, X2", `Z suffix should be the last; unknown suffix "A"`},
		{"VADDPD.Z.Z X0, X1, X2", `Z suffix should be the last; duplicate suffix "Z"`},

			case scanner.Ident:
				if !acceptArg {
					in.Error("bad syntax in definition for macro:", name)
				}
				arg := in.Stack.Text()
				if i := lookup(args, arg); i >= 0 {
					in.Error("duplicate argument", arg, "in definition for macro:", name)
				}
				args = append(args, arg)
				acceptArg = false
			default:
				in.Error("bad definition for macro:", name)
			}
		}
	}
	var tokens []Token

equations for the respective type parameters.
</p>

<p>
For example, given
</p>

<pre>
// dedup returns a copy of the argument slice with any duplicate entries removed.
func dedup[S ~[]E, E comparable](S) S { … }

type Slice []int
var s Slice
s = dedup(s)   // same as s = dedup[Slice, int](s)
</pre>

<p>

			return err
		}
	}
	if len(w.dir) > 0 && w.dir[len(w.dir)-1].FileHeader == fh {
		// See https://golang.org/issue/11144 confusion.
		return errors.New("archive/zip: invalid duplicate FileHeader")
	}
	return nil
}

// CreateHeader adds a file to the zip archive using the provided [FileHeader]
// for the file metadata. [Writer] takes ownership of fh and may mutate

	f := strings.Join(w.scope, ", ") + ", " + fmt.Sprintf(format, args...)
	if strings.Contains(f, "\n") {
		panic("feature contains newlines: " + f)
	}

	if _, dup := w.features[f]; dup {
		panic("duplicate feature inserted: " + f)
	}
	w.features[f] = true

	if verbose {
		log.Printf("feature: %s", f)
	}
}

func needApproval(filename string) bool {
	name := filepath.Base(filename)