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go/types: use []*TypeParam rather than []*TypeName type param lists

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Making this change improves type safety slightly, and avoids many
internal type assertions.

Change-Id: I26519b0e57068e944e8243983ae90553d79e59c2
Reviewed-on: https://go-review.googlesource.com/c/go/+/343932
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:
Robert Findley 2021-08-19 13:31:36 -04:00
parent 9fe5c7f122
commit 2438660602
11 changed files with 57 additions and 59 deletions
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12
src/go/types/decl.go
View file

@ -632,7 +632,7 @@ func (check *Checker) typeDecl(obj *TypeName, tdecl *ast.TypeSpec, def *Named) {
}
func (check *Checker) collectTypeParams(list *ast.FieldList) *TParamList {
var tparams []*TypeName
var tparams []*TypeParam
// Declare type parameters up-front, with empty interface as type bound.
// The scope of type parameters starts at the beginning of the type parameter
// list (so we can have mutually recursive parameterized interfaces).
@ -648,7 +648,7 @@ func (check *Checker) collectTypeParams(list *ast.FieldList) *TParamList {
}
bound = check.boundType(f.Type)
for i := range f.Names {
tparams[index+i].typ.(*TypeParam).bound = bound
tparams[index+i].bound = bound
}
next:
@ -658,11 +658,11 @@ func (check *Checker) collectTypeParams(list *ast.FieldList) *TParamList {
return bindTParams(tparams)
}
func (check *Checker) declareTypeParams(tparams []*TypeName, names []*ast.Ident) []*TypeName {
func (check *Checker) declareTypeParams(tparams []*TypeParam, names []*ast.Ident) []*TypeParam {
for _, name := range names {
tpar := NewTypeName(name.Pos(), check.pkg, name.Name, nil)
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
tname := NewTypeName(name.Pos(), check.pkg, name.Name, nil)
tpar := check.NewTypeParam(tname, &emptyInterface) // assigns type to tpar as a side-effect
check.declare(check.scope, name, tname, check.scope.pos) // TODO(gri) check scope position
tparams = append(tparams, tpar)
}

32
src/go/types/infer.go
View file

@ -27,7 +27,7 @@ import (
//
// Constraint type inference is used after each step to expand the set of type arguments.
//
func (check *Checker) infer(posn positioner, tparams []*TypeName, targs []Type, params *Tuple, args []*operand, report bool) (result []Type) {
func (check *Checker) infer(posn positioner, tparams []*TypeParam, targs []Type, params *Tuple, args []*operand, report bool) (result []Type) {
if debug {
defer func() {
assert(result == nil || len(result) == len(tparams))
@ -121,7 +121,7 @@ func (check *Checker) infer(posn positioner, tparams []*TypeName, targs []Type,
}
}
if allFailed {
check.errorf(arg, _Todo, "%s %s of %s does not match %s (cannot infer %s)", kind, targ, arg.expr, tpar, typeNamesString(tparams))
check.errorf(arg, _Todo, "%s %s of %s does not match %s (cannot infer %s)", kind, targ, arg.expr, tpar, typeParamsString(tparams))
return
}
}
@ -218,23 +218,23 @@ func (check *Checker) infer(posn positioner, tparams []*TypeName, targs []Type,
assert(index >= 0 && targs[index] == nil)
tpar := tparams[index]
if report {
check.errorf(posn, _Todo, "cannot infer %s (%v) (%v)", tpar.name, tpar.pos, targs)
check.errorf(posn, _Todo, "cannot infer %s (%v) (%v)", tpar.obj.name, tpar.obj.pos, targs)
}
return nil
}
// typeNamesString produces a string containing all the
// type names in list suitable for human consumption.
func typeNamesString(list []*TypeName) string {
// typeParamsString produces a string containing all the type parameter names
// in list suitable for human consumption.
func typeParamsString(list []*TypeParam) string {
// common cases
n := len(list)
switch n {
case 0:
return ""
case 1:
return list[0].name
return list[0].obj.name
case 2:
return list[0].name + " and " + list[1].name
return list[0].obj.name + " and " + list[1].obj.name
}
// general case (n > 2)
@ -243,15 +243,15 @@ func typeNamesString(list []*TypeName) string {
if i > 0 {
b.WriteString(", ")
}
b.WriteString(tname.name)
b.WriteString(tname.obj.name)
}
b.WriteString(", and ")
b.WriteString(list[n-1].name)
b.WriteString(list[n-1].obj.name)
return b.String()
}
// IsParameterized reports whether typ contains any of the type parameters of tparams.
func isParameterized(tparams []*TypeName, typ Type) bool {
func isParameterized(tparams []*TypeParam, typ Type) bool {
w := tpWalker{
seen: make(map[Type]bool),
tparams: tparams,
@ -261,7 +261,7 @@ func isParameterized(tparams []*TypeName, typ Type) bool {
type tpWalker struct {
seen map[Type]bool
tparams []*TypeName
tparams []*TypeParam
}
func (w *tpWalker) isParameterized(typ Type) (res bool) {
@ -334,7 +334,7 @@ func (w *tpWalker) isParameterized(typ Type) (res bool) {
case *TypeParam:
// t must be one of w.tparams
return t.index < len(w.tparams) && w.tparams[t.index].typ == t
return t.index < len(w.tparams) && w.tparams[t.index] == t
default:
unreachable()
@ -360,7 +360,7 @@ func (w *tpWalker) isParameterizedTypeList(list []Type) bool {
// first type argument in that list that couldn't be inferred (and thus is nil). If all
// type arguments were inferred successfully, index is < 0. The number of type arguments
// provided may be less than the number of type parameters, but there must be at least one.
func (check *Checker) inferB(tparams []*TypeName, targs []Type, report bool) (types []Type, index int) {
func (check *Checker) inferB(tparams []*TypeParam, targs []Type, report bool) (types []Type, index int) {
assert(len(tparams) >= len(targs) && len(targs) > 0)
// Setup bidirectional unification between those structural bounds
@ -378,12 +378,12 @@ func (check *Checker) inferB(tparams []*TypeName, targs []Type, report bool) (ty
// Unify type parameters with their structural constraints, if any.
for _, tpar := range tparams {
typ := tpar.typ.(*TypeParam)
typ := tpar
sbound := typ.structuralType()
if sbound != nil {
if !u.unify(typ, sbound) {
if report {
check.errorf(tpar, _Todo, "%s does not match %s", tpar, sbound)
check.errorf(tpar.obj, _Todo, "%s does not match %s", tpar.obj, sbound)
}
return nil, 0
}

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

@ -48,7 +48,7 @@ func Instantiate(env *Environment, typ Type, targs []Type, validate bool) (Type,
var err error
if validate {
var tparams []*TypeName
var tparams []*TypeParam
switch t := typ.(type) {
case *Named:
tparams = t.TParams().list()
@ -90,7 +90,7 @@ func (check *Checker) instantiate(pos token.Pos, typ Type, targs []Type, posList
check.later(func() {
// Collect tparams again because lazily loaded *Named types may not have
// had tparams set up above.
var tparams []*TypeName
var tparams []*TypeParam
switch t := typ.(type) {
case *Named:
tparams = t.TParams().list()
@ -186,11 +186,11 @@ func (check *Checker) validateTArgLen(pos token.Pos, tparams *TParamList, targs
return true
}
func (check *Checker) verify(pos token.Pos, tparams []*TypeName, targs []Type) (int, error) {
func (check *Checker) verify(pos token.Pos, tparams []*TypeParam, targs []Type) (int, error) {
smap := makeSubstMap(tparams, targs)
for i, tname := range tparams {
for i, tpar := range tparams {
// stop checking bounds after the first failure
if err := check.satisfies(pos, targs[i], tname.typ.(*TypeParam), smap); err != nil {
if err := check.satisfies(pos, targs[i], tpar, smap); err != nil {
return i, err
}
}

4
src/go/types/named.go
View file

@ -24,7 +24,7 @@ type Named struct {
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
resolve func(*Named) ([]*TypeName, Type, []*Func)
resolve func(*Named) ([]*TypeParam, Type, []*Func)
once sync.Once
}
@ -126,7 +126,7 @@ func (t *Named) _Orig() *Named { return t.orig }
func (t *Named) TParams() *TParamList { return t.load().tparams }
// SetTParams sets the type parameters of the named type t.
func (t *Named) SetTParams(tparams []*TypeName) { t.load().tparams = bindTParams(tparams) }
func (t *Named) SetTParams(tparams []*TypeParam) { t.load().tparams = bindTParams(tparams) }
// NumTArgs returns the number of type arguments used to instantiate the named
// type t, or 0 if t is not an instantiated type.

2
src/go/types/object.go
View file

@ -232,7 +232,7 @@ func NewTypeName(pos token.Pos, pkg *Package, name string, typ Type) *TypeName {
// _NewTypeNameLazy returns a new defined type like NewTypeName, but it
// lazily calls resolve to finish constructing the Named object.
func _NewTypeNameLazy(pos token.Pos, pkg *Package, name string, resolve func(named *Named) (tparams []*TypeName, underlying Type, methods []*Func)) *TypeName {
func _NewTypeNameLazy(pos token.Pos, pkg *Package, name string, resolve func(named *Named) (tparams []*TypeParam, underlying Type, methods []*Func)) *TypeName {
obj := NewTypeName(pos, pkg, name, nil)
NewNamed(obj, nil, nil).resolve = resolve
return obj

4
src/go/types/predicates.go
View file

@ -351,13 +351,13 @@ func identical(x, y Type, cmpTags bool, p *ifacePair) bool {
return false
}
func identicalTParams(x, y []*TypeName, cmpTags bool, p *ifacePair) bool {
func identicalTParams(x, y []*TypeParam, cmpTags bool, p *ifacePair) bool {
if len(x) != len(y) {
return false
}
for i, x := range x {
y := y[i]
if !identical(x.typ.(*TypeParam).bound, y.typ.(*TypeParam).bound, cmpTags, p) {
if !identical(x.bound, y.bound, cmpTags, p) {
return false
}
}

16
src/go/types/signature.go
View file

@ -59,13 +59,13 @@ func (s *Signature) Recv() *Var { return s.recv }
func (s *Signature) TParams() *TParamList { return s.tparams }
// SetTParams sets the type parameters of signature s.
func (s *Signature) SetTParams(tparams []*TypeName) { s.tparams = bindTParams(tparams) }
func (s *Signature) SetTParams(tparams []*TypeParam) { s.tparams = bindTParams(tparams) }
// RParams returns the receiver type parameters of signature s, or nil.
func (s *Signature) RParams() *TParamList { return s.rparams }
// SetRParams sets the receiver type params of signature s.
func (s *Signature) SetRParams(rparams []*TypeName) { s.rparams = bindTParams(rparams) }
func (s *Signature) SetRParams(rparams []*TypeParam) { s.rparams = bindTParams(rparams) }
// Params returns the parameters of signature s, or nil.
func (s *Signature) Params() *Tuple { return s.params }
@ -121,7 +121,7 @@ func (check *Checker) funcType(sig *Signature, recvPar *ast.FieldList, ftyp *ast
sig.rparams = bindTParams(check.declareTypeParams(nil, rparams))
// determine receiver type to get its type parameters
// and the respective type parameter bounds
var recvTParams []*TypeName
var recvTParams []*TypeParam
if rname != nil {
// recv should be a Named type (otherwise an error is reported elsewhere)
// Also: Don't report an error via genericType since it will be reported
@ -137,19 +137,19 @@ func (check *Checker) funcType(sig *Signature, recvPar *ast.FieldList, ftyp *ast
// We have a list of *TypeNames but we need a list of Types.
list := make([]Type, sig.RParams().Len())
for i, t := range sig.RParams().list() {
list[i] = t.typ
list[i] = t
}
smap := makeSubstMap(recvTParams, list)
for i, tname := range sig.RParams().list() {
bound := recvTParams[i].typ.(*TypeParam).bound
for i, tpar := range sig.RParams().list() {
bound := recvTParams[i].bound
// bound is (possibly) parameterized in the context of the
// receiver type declaration. Substitute parameters for the
// current context.
// TODO(gri) should we assume now that bounds always exist?
// (no bound == empty interface)
if bound != nil {
bound = check.subst(tname.pos, bound, smap, nil)
tname.typ.(*TypeParam).bound = bound
bound = check.subst(tpar.obj.pos, bound, smap, nil)
tpar.bound = bound
}
}
}

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

@ -18,11 +18,11 @@ type substMap map[*TypeParam]Type
// makeSubstMap creates a new substitution map mapping tpars[i] to targs[i].
// If targs[i] is nil, tpars[i] is not substituted.
func makeSubstMap(tpars []*TypeName, targs []Type) substMap {
func makeSubstMap(tpars []*TypeParam, targs []Type) substMap {
assert(len(tpars) == len(targs))
proj := make(substMap, len(tpars))
for i, tpar := range tpars {
proj[tpar.typ.(*TypeParam)] = targs[i]
proj[tpar] = targs[i]
}
return proj
}

11
src/go/types/typeparam.go
View file

@ -89,7 +89,7 @@ func (t *TypeParam) Underlying() Type { return t }
func (t *TypeParam) String() string { return TypeString(t, nil) }
// TParamList holds a list of type parameters bound to a type.
type TParamList struct{ tparams []*TypeName }
type TParamList struct{ tparams []*TypeParam }
// Len returns the number of type parameters in the list.
// It is safe to call on a nil receiver.
@ -98,23 +98,22 @@ func (tps *TParamList) Len() int {
}
// At returns the i'th type parameter in the list.
func (tps *TParamList) At(i int) *TypeName {
func (tps *TParamList) At(i int) *TypeParam {
return tps.list()[i]
}
func (tps *TParamList) list() []*TypeName {
func (tps *TParamList) list() []*TypeParam {
if tps == nil {
return nil
}
return tps.tparams
}
func bindTParams(list []*TypeName) *TParamList {
func bindTParams(list []*TypeParam) *TParamList {
if len(list) == 0 {
return nil
}
for i, tp := range list {
typ := tp.Type().(*TypeParam)
for i, typ := range list {
if typ.index >= 0 {
panic("type parameter bound more than once")
}

7
src/go/types/typestring.go
View file

@ -244,15 +244,14 @@ func writeTypeList(buf *bytes.Buffer, list []Type, qf Qualifier, visited []Type)
}
}
func writeTParamList(buf *bytes.Buffer, list []*TypeName, qf Qualifier, visited []Type) {
func writeTParamList(buf *bytes.Buffer, list []*TypeParam, qf Qualifier, visited []Type) {
// TODO(rFindley) compare this with the corresponding implementation in types2
buf.WriteString("[")
var prev Type
for i, p := range list {
for i, tpar := range list {
// Determine the type parameter and its constraint.
// list is expected to hold type parameter names,
// but don't crash if that's not the case.
tpar, _ := p.typ.(*TypeParam)
var bound Type
if tpar != nil {
bound = tpar.bound // should not be nil but we want to see it if it is
@ -271,7 +270,7 @@ func writeTParamList(buf *bytes.Buffer, list []*TypeName, qf Qualifier, visited
if tpar != nil {
writeType(buf, tpar, qf, visited)
} else {
buf.WriteString(p.name)
buf.WriteString(tpar.obj.name)
}
}
if prev != nil {

14
src/go/types/unify.go
View file

@ -63,7 +63,7 @@ func (u *unifier) unify(x, y Type) bool {
// A tparamsList describes a list of type parameters and the types inferred for them.
type tparamsList struct {
unifier *unifier
tparams []*TypeName
tparams []*TypeParam
// For each tparams element, there is a corresponding type slot index in indices.
// index < 0: unifier.types[-index-1] == nil
// index == 0: no type slot allocated yet
@ -78,11 +78,11 @@ type tparamsList struct {
func (d *tparamsList) String() string {
var buf bytes.Buffer
buf.WriteByte('[')
for i, tname := range d.tparams {
for i, tpar := range d.tparams {
if i > 0 {
buf.WriteString(", ")
}
writeType(&buf, tname.typ, nil, nil)
writeType(&buf, tpar, nil, nil)
buf.WriteString(": ")
writeType(&buf, d.at(i), nil, nil)
}
@ -93,13 +93,13 @@ func (d *tparamsList) String() string {
// init initializes d with the given type parameters.
// The type parameters must be in the order in which they appear in their declaration
// (this ensures that the tparams indices match the respective type parameter index).
func (d *tparamsList) init(tparams []*TypeName) {
func (d *tparamsList) init(tparams []*TypeParam) {
if len(tparams) == 0 {
return
}
if debug {
for i, tpar := range tparams {
assert(i == tpar.typ.(*TypeParam).index)
assert(i == tpar.index)
}
}
d.tparams = tparams
@ -155,8 +155,8 @@ func (d *tparamsList) index(typ Type) int {
// If tpar is a type parameter in list, tparamIndex returns the type parameter index.
// Otherwise, the result is < 0. tpar must not be nil.
func tparamIndex(list []*TypeName, tpar *TypeParam) int {
if i := tpar.index; i < len(list) && list[i].typ == tpar {
func tparamIndex(list []*TypeParam, tpar *TypeParam) int {
if i := tpar.index; i < len(list) && list[i] == tpar {
return i
}
return -1