go/types: unexport UniverseByte/Rune; make Typ a slice

Also: backport https://go-review.googlesource.com/#/c/12443/ .

Change-Id: Ia8a664c627a70a17701b2d48946704c15f4f49c0
Reviewed-on: https://go-review.googlesource.com/12482
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

go/gccgoimporter/parser.go

@@ -659,8 +659,8 @@ func lookupBuiltinType(typ int) types.Type {
 		gccgoBuiltinCOMPLEX64:  types.Typ[types.Complex64],
 		gccgoBuiltinCOMPLEX128: types.Typ[types.Complex128],
 		gccgoBuiltinERROR:      types.Universe.Lookup("error").Type(),
-		gccgoBuiltinBYTE:       types.Typ[types.Byte],
+		gccgoBuiltinBYTE:       types.Universe.Lookup("byte").Type(),
-		gccgoBuiltinRUNE:       types.Typ[types.Rune],
+		gccgoBuiltinRUNE:       types.Universe.Lookup("rune").Type(),
 	}[typ]
 }
 

go/importer/predefined.go

@@ -76,8 +76,9 @@ var predeclared = []types.Type{
 	types.Typ[types.UnsafePointer],
 
 	// aliases
-	types.UniverseByte,
+	types.Universe.Lookup("byte").Type(),
-	types.UniverseRune,
+	types.Universe.Lookup("rune").Type(),
 
+	// error
 	types.Universe.Lookup("error").Type(),
 }

go/types/builtins.go

@@ -96,7 +96,7 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 		// spec: "As a special case, append also accepts a first argument assignable
 		// to type []byte with a second argument of string type followed by ... .
 		// This form appends the bytes of the string.
-		if nargs == 2 && call.Ellipsis.IsValid() && x.assignableTo(check.conf, NewSlice(UniverseByte)) {
+		if nargs == 2 && call.Ellipsis.IsValid() && x.assignableTo(check.conf, NewSlice(universeByte)) {
 			arg(x, 1)
 			if x.mode == invalid {
 				return
@@ -289,7 +289,7 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 		switch t := y.typ.Underlying().(type) {
 		case *Basic:
 			if isString(y.typ) {
-				src = UniverseByte
+				src = universeByte
 			}
 		case *Slice:
 			src = t.elem

go/types/expr.go

@@ -1183,7 +1183,7 @@ func (check *Checker) exprInternal(x *operand, e ast.Expr, hint Type) exprKind {
 				// (not a constant) even if the string and the
 				// index are constant
 				x.mode = value
-				x.typ = UniverseByte // use 'byte' name
+				x.typ = universeByte // use 'byte' name
 			}
 
 		case *Array:

go/types/predicates.go

@@ -296,7 +296,7 @@ func defaultType(typ Type) Type {
 		case UntypedInt:
 			return Typ[Int]
 		case UntypedRune:
-			return UniverseRune // use 'rune' name
+			return universeRune // use 'rune' name
 		case UntypedFloat:
 			return Typ[Float64]
 		case UntypedComplex:

go/types/stmt.go

@@ -629,7 +629,7 @@ func (check *Checker) stmt(ctxt stmtContext, s ast.Stmt) {
 			case *Basic:
 				if isString(typ) {
 					key = Typ[Int]
-					val = UniverseRune // use 'rune' name
+					val = universeRune // use 'rune' name
 				}
 			case *Array:
 				key = Typ[Int]

go/types/universe.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// This file implements the universe and unsafe package scopes.
+// This file sets up the universe scope and the unsafe package.
 
 package types
 
@@ -17,11 +17,11 @@ var (
 	Universe     *Scope
 	Unsafe       *Package
 	universeIota *Const
-	UniverseByte *Basic // uint8 alias, but has name "byte"
+	universeByte *Basic // uint8 alias, but has name "byte"
-	UniverseRune *Basic // int32 alias, but has name "rune"
+	universeRune *Basic // int32 alias, but has name "rune"
 )
 
-var Typ = [...]*Basic{
+var Typ = []*Basic{
 	Invalid: {Invalid, 0, "invalid type"},
 
 	Bool:          {Bool, IsBoolean, "bool"},
@@ -187,8 +187,8 @@ func init() {
 	defPredeclaredFuncs()
 
 	universeIota = Universe.Lookup("iota").(*Const)
-	UniverseByte = Universe.Lookup("byte").(*TypeName).typ.(*Basic)
+	universeByte = Universe.Lookup("byte").(*TypeName).typ.(*Basic)
-	UniverseRune = Universe.Lookup("rune").(*TypeName).typ.(*Basic)
+	universeRune = Universe.Lookup("rune").(*TypeName).typ.(*Basic)
 }
 
 // Objects with names containing blanks are internal and not entered into