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[dev.typeparams] go/types: set type parameter indices when they are bound

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It is invalid to use a type parameter for more than one type, so we can
avoid passing the type parameter index to NewTypeParam and just set it
when type parameters are bound to a type via SetTParams or during type
checking.

In order to enforce the correctness of this change, introduce a
TypeParams type to represent a list of type parameters that have been
associated with a type. For now, expose this new type as the API for
type parameters, but this is of course not necessarily a final API.

Allowing *TypeParams to be nil also decreases the size of Named and
Signature, which is good as most instances of these types will not be
parameterized.

Change-Id: Ia1e39ba51edb05bb535eb5f41c34e9dd02d39c38
Reviewed-on: https://go-review.googlesource.com/c/go/+/336249
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>
This commit is contained in:
Rob Findley 2021-07-21 10:21:23 -04:00 committed by Robert Findley
parent 311baf65f4
commit 6f57139c7a
17 changed files with 111 additions and 65 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
src/go/types/api_test.go
View File

@ -1828,7 +1828,7 @@ func TestInstantiate(t *testing.T) {
// type T should have one type parameter
T := pkg.Scope().Lookup("T").Type().(*Named)
if n := len(T.TParams()); n != 1 {
if n := T.TParams().Len(); n != 1 {
t.Fatalf("expected 1 type parameter; found %d", n)
}

2
src/go/types/assignments.go
View File

@ -71,7 +71,7 @@ func (check *Checker) assignment(x *operand, T Type, context string) {
}
// A generic (non-instantiated) function value cannot be assigned to a variable.
if sig := asSignature(x.typ); sig != nil && len(sig.tparams) > 0 {
if sig := asSignature(x.typ); sig != nil && sig.TParams().Len() > 0 {
check.errorf(x, _Todo, "cannot use generic function %s without instantiation in %s", x, context)
}

3
src/go/types/builtins.go
View File

@ -806,7 +806,8 @@ func (check *Checker) applyTypeFunc(f func(Type) Type, x Type) Type {
// type param is placed in the current package so export/import
// works as expected.
tpar := NewTypeName(token.NoPos, check.pkg, "<type parameter>", nil)
ptyp := check.NewTypeParam(tpar, tp.index, &emptyInterface) // assigns type to tpar as a side-effect
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}}

20
src/go/types/call.go
View File

@ -27,7 +27,7 @@ func (check *Checker) funcInst(x *operand, ix *typeparams.IndexExpr) {
// check number of type arguments (got) vs number of type parameters (want)
sig := x.typ.(*Signature)
got, want := len(targs), len(sig.tparams)
got, want := len(targs), sig.TParams().Len()
if got > want {
check.errorf(ix.Indices[got-1], _Todo, "got %d type arguments but want %d", got, want)
x.mode = invalid
@ -39,7 +39,7 @@ func (check *Checker) funcInst(x *operand, ix *typeparams.IndexExpr) {
inferred := false
if got < want {
targs = check.infer(ix.Orig, sig.tparams, targs, nil, nil, true)
targs = check.infer(ix.Orig, sig.TParams().list(), targs, nil, nil, true)
if targs == nil {
// error was already reported
x.mode = invalid
@ -160,7 +160,7 @@ func (check *Checker) callExpr(x *operand, call *ast.CallExpr) exprKind {
assert(len(targs) == len(ix.Indices))
// check number of type arguments (got) vs number of type parameters (want)
got, want := len(targs), len(sig.tparams)
got, want := len(targs), sig.TParams().Len()
if got > want {
check.errorf(ix.Indices[want], _Todo, "got %d type arguments but want %d", got, want)
check.use(call.Args...)
@ -194,7 +194,7 @@ func (check *Checker) callExpr(x *operand, call *ast.CallExpr) exprKind {
// if type inference failed, a parametrized result must be invalidated
// (operands cannot have a parametrized type)
if x.mode == value && len(sig.tparams) > 0 && isParameterized(sig.tparams, x.typ) {
if x.mode == value && sig.TParams().Len() > 0 && isParameterized(sig.TParams().list(), x.typ) {
x.mode = invalid
}
@ -324,10 +324,10 @@ func (check *Checker) arguments(call *ast.CallExpr, sig *Signature, targs []Type
}
// infer type arguments and instantiate signature if necessary
if len(sig.tparams) > 0 {
if sig.TParams().Len() > 0 {
// TODO(gri) provide position information for targs so we can feed
// it to the instantiate call for better error reporting
targs := check.infer(call, sig.tparams, targs, sigParams, args, true)
targs := check.infer(call, sig.TParams().list(), targs, sigParams, args, true)
if targs == nil {
return // error already reported
}
@ -341,7 +341,7 @@ func (check *Checker) arguments(call *ast.CallExpr, sig *Signature, targs []Type
// need to compute it from the adjusted list; otherwise we can
// simply use the result signature's parameter list.
if adjusted {
sigParams = check.subst(call.Pos(), sigParams, makeSubstMap(sig.tparams, targs)).(*Tuple)
sigParams = check.subst(call.Pos(), sigParams, makeSubstMap(sig.TParams().list(), targs)).(*Tuple)
} else {
sigParams = rsig.params
}
@ -517,7 +517,7 @@ func (check *Checker) selector(x *operand, e *ast.SelectorExpr) {
// the signature accordingly.
// TODO(gri) factor this code out
sig := m.typ.(*Signature)
if len(sig.rparams) > 0 {
if sig.RParams().Len() > 0 {
// For inference to work, we must use the receiver type
// matching the receiver in the actual method declaration.
// If the method is embedded, the matching receiver is the
@ -545,7 +545,7 @@ func (check *Checker) selector(x *operand, e *ast.SelectorExpr) {
// the receiver type arguments here, the receiver must be be otherwise invalid
// and an error has been reported elsewhere.
arg := operand{mode: variable, expr: x.expr, typ: recv}
targs := check.infer(m, sig.rparams, nil, NewTuple(sig.recv), []*operand{&arg}, false /* no error reporting */)
targs := check.infer(m, sig.RParams().list(), nil, NewTuple(sig.recv), []*operand{&arg}, false /* no error reporting */)
if targs == nil {
// We may reach here if there were other errors (see issue #40056).
goto Error
@ -554,7 +554,7 @@ func (check *Checker) selector(x *operand, e *ast.SelectorExpr) {
// (If we modify m, some tests will fail; possibly because the m is in use.)
// TODO(gri) investigate and provide a correct explanation here
copy := *m
copy.typ = check.subst(e.Pos(), m.typ, makeSubstMap(sig.rparams, targs))
copy.typ = check.subst(e.Pos(), m.typ, makeSubstMap(sig.RParams().list(), targs))
obj = &copy
}
// TODO(gri) we also need to do substitution for parameterized interface methods

8
src/go/types/decl.go
View File

@ -625,13 +625,13 @@ func (check *Checker) typeDecl(obj *TypeName, tdecl *ast.TypeSpec, def *Named) {
named.underlying = under(named)
// If the RHS is a type parameter, it must be from this type declaration.
if tpar, _ := named.underlying.(*TypeParam); tpar != nil && tparamIndex(named.tparams, tpar) < 0 {
if tpar, _ := named.underlying.(*TypeParam); tpar != nil && tparamIndex(named.tparams.list(), tpar) < 0 {
check.errorf(tdecl.Type, _Todo, "cannot use function type parameter %s as RHS in type declaration", tpar)
named.underlying = Typ[Invalid]
}
}
func (check *Checker) collectTypeParams(list *ast.FieldList) []*TypeName {
func (check *Checker) collectTypeParams(list *ast.FieldList) *TypeParams {
var tparams []*TypeName
// Declare type parameters up-front, with empty interface as type bound.
// The scope of type parameters starts at the beginning of the type parameter
@ -655,13 +655,13 @@ func (check *Checker) collectTypeParams(list *ast.FieldList) []*TypeName {
index += len(f.Names)
}
return tparams
return bindTParams(tparams)
}
func (check *Checker) declareTypeParams(tparams []*TypeName, names []*ast.Ident) []*TypeName {
for _, name := range names {
tpar := NewTypeName(name.Pos(), check.pkg, name.Name, nil)
check.NewTypeParam(tpar, len(tparams), &emptyInterface) // assigns type to tpar as a side-effect
check.NewTypeParam(tpar, &emptyInterface) // assigns type to tpar as a side-effect
check.declare(check.scope, name, tpar, check.scope.pos) // TODO(gri) check scope position
tparams = append(tparams, tpar)
}

2
src/go/types/index.go
View File

@ -33,7 +33,7 @@ func (check *Checker) indexExpr(x *operand, e *typeparams.IndexExpr) (isFuncInst
return false
case value:
if sig := asSignature(x.typ); sig != nil && len(sig.tparams) > 0 {
if sig := asSignature(x.typ); sig != nil && sig.TParams().Len() > 0 {
// function instantiation
return true
}

2
src/go/types/instance.go
View File

@ -24,7 +24,7 @@ type instance struct {
func (n *Named) complete() {
if n.instance != nil && len(n.targs) > 0 && n.underlying == nil {
check := n.instance.check
inst := check.instantiate(n.instance.pos, n.orig.underlying, n.tparams, n.targs, n.instance.posList)
inst := check.instantiate(n.instance.pos, n.orig.underlying, n.TParams().list(), n.targs, n.instance.posList)
n.underlying = inst
n.fromRHS = inst
n.methods = n.orig.methods

10
src/go/types/instantiate.go
View File

@ -28,9 +28,9 @@ func (check *Checker) Instantiate(pos token.Pos, typ Type, targs []Type, posList
var tparams []*TypeName
switch t := typ.(type) {
case *Named:
tparams = t.TParams()
tparams = t.TParams().list()
case *Signature:
tparams = t.tparams
tparams = t.TParams().list()
defer func() {
// If we had an unexpected failure somewhere don't panic below when
// asserting res.(*Signature). Check for *Signature in case Typ[Invalid]
@ -109,9 +109,9 @@ func (check *Checker) InstantiateLazy(pos token.Pos, typ Type, targs []Type, pos
if base == nil {
panic(fmt.Sprintf("%v: cannot instantiate %v", pos, typ))
}
if verify && len(base.tparams) == len(targs) {
if verify && base.TParams().Len() == len(targs) {
check.later(func() {
check.verify(pos, base.tparams, targs, posList)
check.verify(pos, base.tparams.list(), targs, posList)
})
}
h := instantiatedHash(base, targs)
@ -122,7 +122,7 @@ func (check *Checker) InstantiateLazy(pos token.Pos, typ Type, targs []Type, pos
}
tname := NewTypeName(pos, base.obj.pkg, base.obj.name, nil)
named := check.newNamed(tname, base, nil, base.tparams, base.methods) // methods are instantiated lazily
named := check.newNamed(tname, base, nil, base.TParams(), base.methods) // methods are instantiated lazily
named.targs = targs
named.instance = &instance{
check: check,

18
src/go/types/lookup.go
View File

@ -317,10 +317,10 @@ func (check *Checker) missingMethod(V Type, T *Interface, static bool) (method,
// both methods must have the same number of type parameters
ftyp := f.typ.(*Signature)
mtyp := m.typ.(*Signature)
if len(ftyp.tparams) != len(mtyp.tparams) {
if ftyp.TParams().Len() != mtyp.TParams().Len() {
return m, f
}
if len(ftyp.tparams) > 0 {
if ftyp.TParams().Len() > 0 {
panic("internal error: method with type parameters")
}
@ -330,7 +330,7 @@ func (check *Checker) missingMethod(V Type, T *Interface, static bool) (method,
// TODO(gri) is this always correct? what about type bounds?
// (Alternative is to rename/subst type parameters and compare.)
u := newUnifier(true)
u.x.init(ftyp.tparams)
u.x.init(ftyp.TParams().list())
if !u.unify(ftyp, mtyp) {
return m, f
}
@ -373,10 +373,10 @@ func (check *Checker) missingMethod(V Type, T *Interface, static bool) (method,
// both methods must have the same number of type parameters
ftyp := f.typ.(*Signature)
mtyp := m.typ.(*Signature)
if len(ftyp.tparams) != len(mtyp.tparams) {
if ftyp.TParams().Len() != mtyp.TParams().Len() {
return m, f
}
if len(ftyp.tparams) > 0 {
if ftyp.TParams().Len() > 0 {
panic("internal error: method with type parameters")
}
@ -387,17 +387,17 @@ func (check *Checker) missingMethod(V Type, T *Interface, static bool) (method,
// In order to compare the signatures, substitute the receiver
// type parameters of ftyp with V's instantiation type arguments.
// This lazily instantiates the signature of method f.
if Vn != nil && len(Vn.TParams()) > 0 {
if Vn != nil && Vn.TParams().Len() > 0 {
// Be careful: The number of type arguments may not match
// the number of receiver parameters. If so, an error was
// reported earlier but the length discrepancy is still
// here. Exit early in this case to prevent an assertion
// failure in makeSubstMap.
// TODO(gri) Can we avoid this check by fixing the lengths?
if len(ftyp.rparams) != len(Vn.targs) {
if len(ftyp.RParams().list()) != len(Vn.targs) {
return
}
ftyp = check.subst(token.NoPos, ftyp, makeSubstMap(ftyp.rparams, Vn.targs)).(*Signature)
ftyp = check.subst(token.NoPos, ftyp, makeSubstMap(ftyp.RParams().list(), Vn.targs)).(*Signature)
}
// If the methods have type parameters we don't care whether they
@ -406,7 +406,7 @@ func (check *Checker) missingMethod(V Type, T *Interface, static bool) (method,
// TODO(gri) is this always correct? what about type bounds?
// (Alternative is to rename/subst type parameters and compare.)
u := newUnifier(true)
u.x.init(ftyp.rparams)
u.x.init(ftyp.RParams().list())
if !u.unify(ftyp, mtyp) {
return m, f
}

16
src/go/types/named.go
View File

@ -16,7 +16,7 @@ type Named struct {
orig *Named // original, uninstantiated type
fromRHS Type // type (on RHS of declaration) this *Named type is derived of (for cycle reporting)
underlying Type // possibly a *Named during setup; never a *Named once set up completely
tparams []*TypeName // type parameters, or nil
tparams *TypeParams // type parameters, or nil
targs []Type // type arguments (after instantiation), or nil
methods []*Func // methods declared for this type (not the method set of this type); signatures are type-checked lazily
@ -56,7 +56,7 @@ func (t *Named) expand() *Named {
panic("invalid underlying type")
}
t.tparams = tparams
t.tparams = bindTParams(tparams)
t.underlying = underlying
t.methods = methods
})
@ -64,7 +64,7 @@ func (t *Named) expand() *Named {
}
// newNamed is like NewNamed but with a *Checker receiver and additional orig argument.
func (check *Checker) newNamed(obj *TypeName, orig *Named, underlying Type, tparams []*TypeName, methods []*Func) *Named {
func (check *Checker) newNamed(obj *TypeName, orig *Named, underlying Type, tparams *TypeParams, methods []*Func) *Named {
var inst *instance
if check != nil {
inst = &instance{
@ -108,14 +108,14 @@ func (t *Named) _Orig() *Named { return t.orig }
// TODO(gri) Come up with a better representation and API to distinguish
// between parameterized instantiated and non-instantiated types.
// _TParams returns the type parameters of the named type t, or nil.
// TParams returns the type parameters of the named type t, or nil.
// The result is non-nil for an (originally) parameterized type even if it is instantiated.
func (t *Named) TParams() []*TypeName { return t.expand().tparams }
func (t *Named) TParams() *TypeParams { return t.expand().tparams }
// _SetTParams sets the type parameters of the named type t.
func (t *Named) SetTParams(tparams []*TypeName) { t.expand().tparams = tparams }
// SetTParams sets the type parameters of the named type t.
func (t *Named) SetTParams(tparams []*TypeName) { t.expand().tparams = bindTParams(tparams) }
// _TArgs returns the type arguments after instantiation of the named type t, or nil if not instantiated.
// TArgs returns the type arguments after instantiation of the named type t, or nil if not instantiated.
func (t *Named) TArgs() []Type { return t.targs }
// SetTArgs sets the type arguments of the named type t.

4
src/go/types/object.go
View File

@ -429,8 +429,8 @@ func writeObject(buf *bytes.Buffer, obj Object, qf Qualifier) {
if _, ok := typ.(*Basic); ok {
return
}
if named, _ := typ.(*Named); named != nil && len(named.tparams) > 0 {
writeTParamList(buf, named.tparams, qf, nil)
if named, _ := typ.(*Named); named != nil && named.TParams().Len() > 0 {
writeTParamList(buf, named.TParams().list(), qf, nil)
}
if tname.IsAlias() {
buf.WriteString(" =")

2
src/go/types/predicates.go
View File

@ -242,7 +242,7 @@ func identical(x, y Type, cmpTags bool, p *ifacePair) bool {
// parameter names.
if y, ok := y.(*Signature); ok {
return x.variadic == y.variadic &&
identicalTParams(x.tparams, y.tparams, cmpTags, p) &&
identicalTParams(x.TParams().list(), y.TParams().list(), cmpTags, p) &&
identical(x.params, y.params, cmpTags, p) &&
identical(x.results, y.results, cmpTags, p)
}

25
src/go/types/signature.go
View File

@ -21,8 +21,8 @@ type Signature struct {
// and store it in the Func Object) because when type-checking a function
// literal we call the general type checker which returns a general Type.
// We then unpack the *Signature and use the scope for the literal body.
rparams []*TypeName // receiver type parameters from left to right, or nil
tparams []*TypeName // type parameters from left to right, or nil
rparams *TypeParams // receiver type parameters from left to right, or nil
tparams *TypeParams // type parameters from left to right, or nil
scope *Scope // function scope, present for package-local signatures
recv *Var // nil if not a method
params *Tuple // (incoming) parameters from left to right; or nil
@ -56,13 +56,16 @@ func NewSignature(recv *Var, params, results *Tuple, variadic bool) *Signature {
func (s *Signature) Recv() *Var { return s.recv }
// TParams returns the type parameters of signature s, or nil.
func (s *Signature) TParams() []*TypeName { return s.tparams }
func (s *Signature) TParams() *TypeParams { return s.tparams }
// SetTParams sets the type parameters of signature s.
func (s *Signature) SetTParams(tparams []*TypeName) { s.tparams = tparams }
func (s *Signature) SetTParams(tparams []*TypeName) { s.tparams = bindTParams(tparams) }
// RParams returns the receiver type parameters of signature s, or nil.
func (s *Signature) RParams() *TypeParams { return s.rparams }
// SetRParams sets the receiver type params of signature s.
func (s *Signature) SetRParams(rparams []*TypeName) { s.rparams = rparams }
func (s *Signature) SetRParams(rparams []*TypeName) { s.rparams = bindTParams(rparams) }
// Params returns the parameters of signature s, or nil.
func (s *Signature) Params() *Tuple { return s.params }
@ -115,7 +118,7 @@ func (check *Checker) funcType(sig *Signature, recvPar *ast.FieldList, ftyp *ast
// blank identifiers were found => use rewritten receiver type
recvTyp = isubst(recvPar.List[0].Type, smap)
}
sig.rparams = check.declareTypeParams(nil, rparams)
sig.rparams = bindTParams(check.declareTypeParams(nil, rparams))
// determine receiver type to get its type parameters
// and the respective type parameter bounds
var recvTParams []*TypeName
@ -125,19 +128,19 @@ func (check *Checker) funcType(sig *Signature, recvPar *ast.FieldList, ftyp *ast
// again when we type-check the signature.
// TODO(gri) maybe the receiver should be marked as invalid instead?
if recv := asNamed(check.genericType(rname, false)); recv != nil {
recvTParams = recv.TParams()
recvTParams = recv.TParams().list()
}
}
// provide type parameter bounds
// - only do this if we have the right number (otherwise an error is reported elsewhere)
if len(sig.rparams) == len(recvTParams) {
if sig.RParams().Len() == len(recvTParams) {
// We have a list of *TypeNames but we need a list of Types.
list := make([]Type, len(sig.rparams))
for i, t := range sig.rparams {
list := make([]Type, sig.RParams().Len())
for i, t := range sig.RParams().list() {
list[i] = t.typ
}
smap := makeSubstMap(recvTParams, list)
for i, tname := range sig.rparams {
for i, tname := range sig.RParams().list() {
bound := recvTParams[i].typ.(*TypeParam).bound
// bound is (possibly) parameterized in the context of the
// receiver type declaration. Substitute parameters for the

4
src/go/types/sizeof_test.go
View File

@ -25,12 +25,12 @@ func TestSizeof(t *testing.T) {
{Struct{}, 24, 48},
{Pointer{}, 8, 16},
{Tuple{}, 12, 24},
{Signature{}, 44, 88},
{Signature{}, 28, 56},
{Union{}, 24, 48},
{Interface{}, 40, 80},
{Map{}, 16, 32},
{Chan{}, 12, 24},
{Named{}, 84, 160},
{Named{}, 76, 144},
{TypeParam{}, 28, 48},
{top{}, 0, 0},

4
src/go/types/subst.go
View File

@ -203,7 +203,7 @@ func (subst *subster) typ(typ Type) Type {
if len(t.targs) > 0 {
// already instantiated
dump(">>> %s already instantiated", t)
assert(len(t.targs) == len(t.TParams()))
assert(len(t.targs) == t.TParams().Len())
// For each (existing) type argument targ, determine if it needs
// to be substituted; i.e., if it is or contains a type parameter
// that has a type argument for it.
@ -213,7 +213,7 @@ func (subst *subster) typ(typ Type) Type {
if newTarg != targ {
dump(">>> substituted %d targ %s => %s", i, targ, newTarg)
if newTargs == nil {
newTargs = make([]Type, len(t.TParams()))
newTargs = make([]Type, t.TParams().Len())
copy(newTargs, t.targs)
}
newTargs[i] = newTarg

50
src/go/types/typeparam.go
View File

@ -28,15 +28,19 @@ type TypeParam struct {
bound Type // *Named or *Interface; underlying type is always *Interface
}
// NewTypeParam returns a new TypeParam. bound can be nil (and set later).
func (check *Checker) NewTypeParam(obj *TypeName, index int, bound Type) *TypeParam {
// NewTypeParam returns a new TypeParam. Type parameters may be set on a Named
// or Signature type by calling SetTParams. Setting a type parameter on more
// than one type will result in a panic.
//
// The bound argument can be nil, and set later via SetBound.
func (check *Checker) NewTypeParam(obj *TypeName, bound Type) *TypeParam {
// Always increment lastID, even if it is not used.
id := nextID()
if check != nil {
check.nextID++
id = check.nextID
}
typ := &TypeParam{check: check, id: id, obj: obj, index: index, bound: bound}
typ := &TypeParam{check: check, id: id, obj: obj, index: -1, bound: bound}
if obj.typ == nil {
obj.typ = typ
}
@ -56,6 +60,8 @@ func (t *TypeParam) _SetId(id uint64) {
t.id = id
}
// TODO(rfindley): document the Bound and SetBound methods.
func (t *TypeParam) Bound() *Interface {
// we may not have an interface (error reported elsewhere)
iface, _ := under(t.bound).(*Interface)
@ -72,7 +78,7 @@ func (t *TypeParam) Bound() *Interface {
return iface
}
func (t *TypeParam) _SetBound(bound Type) {
func (t *TypeParam) SetBound(bound Type) {
if bound == nil {
panic("internal error: bound must not be nil")
}
@ -82,6 +88,42 @@ func (t *TypeParam) _SetBound(bound Type) {
func (t *TypeParam) Underlying() Type { return t }
func (t *TypeParam) String() string { return TypeString(t, nil) }
// TypeParams holds a list of type parameters bound to a type.
type TypeParams struct{ tparams []*TypeName }
// Len returns the number of type parameters in the list.
// It is safe to call on a nil receiver.
func (tps *TypeParams) Len() int {
return len(tps.list())
}
// At returns the i'th type parameter in the list.
// It is safe to call on a nil receiver.
func (tps *TypeParams) At(i int) *TypeName {
return tps.list()[i]
}
func (tps *TypeParams) list() []*TypeName {
if tps == nil {
return nil
}
return tps.tparams
}
func bindTParams(list []*TypeName) *TypeParams {
if len(list) == 0 {
return nil
}
for i, tp := range list {
typ := tp.Type().(*TypeParam)
if typ.index >= 0 {
panic("internal error: type parameter bound more than once")
}
typ.index = i
}
return &TypeParams{tparams: list}
}
// ----------------------------------------------------------------------------
// Implementation

4
src/go/types/typestring.go
View File

@ -278,7 +278,7 @@ func writeType(buf *bytes.Buffer, typ Type, qf Qualifier, visited []Type) {
buf.WriteByte(']')
} else if t.TParams() != nil {
// parameterized type
writeTParamList(buf, t.TParams(), qf, visited)
writeTParamList(buf, t.TParams().list(), qf, visited)
}
case *TypeParam:
@ -425,7 +425,7 @@ func WriteSignature(buf *bytes.Buffer, sig *Signature, qf Qualifier) {
func writeSignature(buf *bytes.Buffer, sig *Signature, qf Qualifier, visited []Type) {
if sig.tparams != nil {
writeTParamList(buf, sig.tparams, qf, visited)
writeTParamList(buf, sig.TParams().list(), qf, visited)
}
writeTuple(buf, sig.params, sig.variadic, qf, visited)