[dev.typeparams] go/types: don't expose the TypeSet API for 1.18

The TypeSet API is very new and probably not necessary to expose outside
of go/types, at least for 1.18. Users can check whether a type is
contained within a type set via Implements, and can access the
representation of the type set via the embedded Unions.

Change-Id: Icc7355285785bee5aa7a8fe74052bcb0fedcd0a1
Reviewed-on: https://go-review.googlesource.com/c/go/+/341289
Trust: Robert Findley <rfindley@google.com>
Run-TryBot: Robert Findley <rfindley@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>

src/go/types/builtins.go

@@ -844,7 +844,7 @@ func (check *Checker) applyTypeFunc(f func(Type) Type, x Type) Type {
 		ptyp := check.NewTypeParam(tpar, &emptyInterface) // assigns type to tpar as a side-effect
 		ptyp.index = tp.index
 		tsum := newUnion(rtypes, tildes)
-		ptyp.bound = &Interface{complete: true, tset: &TypeSet{types: tsum}}
+		ptyp.bound = &Interface{complete: true, tset: &_TypeSet{types: tsum}}
 
 		return ptyp
 	}

src/go/types/interface.go

@@ -21,11 +21,11 @@ type Interface struct {
 	embedPos  *[]token.Pos // positions of embedded elements; or nil (for error messages) - use pointer to save space
 	complete  bool         // indicates that obj, methods, and embeddeds are set and type set can be computed
 
-	tset *TypeSet // type set described by this interface, computed lazily
+	tset *_TypeSet // type set described by this interface, computed lazily
 }
 
 // typeSet returns the type set for interface t.
-func (t *Interface) typeSet() *TypeSet { return computeTypeSet(nil, token.NoPos, t) }
+func (t *Interface) typeSet() *_TypeSet { return computeTypeSet(nil, token.NoPos, t) }
 
 // is reports whether interface t represents types that all satisfy f.
 func (t *Interface) is(f func(Type, bool) bool) bool {

src/go/types/sizeof_test.go

@@ -48,7 +48,7 @@ func TestSizeof(t *testing.T) {
 		// Misc
 		{Scope{}, 44, 88},
 		{Package{}, 40, 80},
-		{TypeSet{}, 24, 48},
+		{_TypeSet{}, 24, 48},
 	}
 	for _, test := range tests {
 		got := reflect.TypeOf(test.val).Size()

src/go/types/typeset.go

@@ -14,8 +14,8 @@ import (
 // ----------------------------------------------------------------------------
 // API
 
-// A TypeSet represents the type set of an interface.
+// A _TypeSet represents the type set of an interface.
-type TypeSet struct {
+type _TypeSet struct {
 	comparable bool // if set, the interface is or embeds comparable
 	// TODO(gri) consider using a set for the methods for faster lookup
 	methods []*Func // all methods of the interface; sorted by unique ID
@@ -23,14 +23,14 @@ type TypeSet struct {
 }
 
 // IsTop reports whether type set s is the top type set (corresponding to the empty interface).
-func (s *TypeSet) IsTop() bool { return !s.comparable && len(s.methods) == 0 && s.types == nil }
+func (s *_TypeSet) IsTop() bool { return !s.comparable && len(s.methods) == 0 && s.types == nil }
 
 // IsMethodSet reports whether the type set s is described by a single set of methods.
-func (s *TypeSet) IsMethodSet() bool { return !s.comparable && s.types == nil }
+func (s *_TypeSet) IsMethodSet() bool { return !s.comparable && s.types == nil }
 
 // IsComparable reports whether each type in the set is comparable.
 // TODO(gri) this is not correct - there may be s.types values containing non-comparable types
-func (s *TypeSet) IsComparable() bool {
+func (s *_TypeSet) IsComparable() bool {
 	if s.types == nil {
 		return s.comparable
 	}
@@ -46,24 +46,24 @@ func (s *TypeSet) IsComparable() bool {
 // TODO(gri) IsTypeSet is not a great name. Find a better one.
 
 // IsTypeSet reports whether the type set s is represented by a finite set of underlying types.
-func (s *TypeSet) IsTypeSet() bool {
+func (s *_TypeSet) IsTypeSet() bool {
 	return !s.comparable && len(s.methods) == 0
 }
 
 // NumMethods returns the number of methods available.
-func (s *TypeSet) NumMethods() int { return len(s.methods) }
+func (s *_TypeSet) NumMethods() int { return len(s.methods) }
 
 // Method returns the i'th method of type set s for 0 <= i < s.NumMethods().
 // The methods are ordered by their unique ID.
-func (s *TypeSet) Method(i int) *Func { return s.methods[i] }
+func (s *_TypeSet) Method(i int) *Func { return s.methods[i] }
 
 // LookupMethod returns the index of and method with matching package and name, or (-1, nil).
-func (s *TypeSet) LookupMethod(pkg *Package, name string) (int, *Func) {
+func (s *_TypeSet) LookupMethod(pkg *Package, name string) (int, *Func) {
 	// TODO(gri) s.methods is sorted - consider binary search
 	return lookupMethod(s.methods, pkg, name)
 }
 
-func (s *TypeSet) String() string {
+func (s *_TypeSet) String() string {
 	if s.IsTop() {
 		return "⊤"
 	}
@@ -102,7 +102,7 @@ func (s *TypeSet) String() string {
 // enumerable types in the type set s. If the type set comprises all types
 // f is called once with the top type; if the type set is empty, the result
 // is false.
-func (s *TypeSet) underIs(f func(Type) bool) bool {
+func (s *_TypeSet) underIs(f func(Type) bool) bool {
 	switch t := s.types.(type) {
 	case nil:
 		return f(theTop)
@@ -114,10 +114,10 @@ func (s *TypeSet) underIs(f func(Type) bool) bool {
 }
 
 // topTypeSet may be used as type set for the empty interface.
-var topTypeSet TypeSet
+var topTypeSet _TypeSet
 
 // computeTypeSet may be called with check == nil.
-func computeTypeSet(check *Checker, pos token.Pos, ityp *Interface) *TypeSet {
+func computeTypeSet(check *Checker, pos token.Pos, ityp *Interface) *_TypeSet {
 	if ityp.tset != nil {
 		return ityp.tset
 	}
@@ -157,7 +157,7 @@ func computeTypeSet(check *Checker, pos token.Pos, ityp *Interface) *TypeSet {
 	// have valid interfaces. Mark the interface as complete to avoid
 	// infinite recursion if the validType check occurs later for some
 	// reason.
-	ityp.tset = new(TypeSet) // TODO(gri) is this sufficient?
+	ityp.tset = new(_TypeSet) // TODO(gri) is this sufficient?
 
 	// Methods of embedded interfaces are collected unchanged; i.e., the identity
 	// of a method I.m's Func Object of an interface I is the same as that of

src/go/types/universe.go

@@ -100,7 +100,7 @@ func defPredeclaredTypes() {
 	{
 		obj := NewTypeName(token.NoPos, nil, "comparable", nil)
 		obj.setColor(black)
-		ityp := &Interface{obj, nil, nil, nil, true, &TypeSet{true, nil, nil}}
+		ityp := &Interface{obj, nil, nil, nil, true, &_TypeSet{true, nil, nil}}
 		NewNamed(obj, ityp, nil)
 		def(obj)
 	}