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[dev.typeparams] cmd/compile/internal/types2: introduce type set abstraction for interfaces

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With this change, interfaces are "completed" on-demand, when needed,
and the respective information (set of all methods, type constraints)
is recorded in a new typeSet data structure.

As a consequence, interfaces don't need to be explicitly completed
anymore and (internal) uses of interfaces have become much simpler.

This change also introduces a new field Interface.complete to indicate
that all methods and embedded elements have been set up. This prevent
the computation and recording (!) of a partial type set for erroneous
programs (if we compute the partial type set and store it, subsequent
type set accesses use the wrong type set which may lead to follow-on
errors).

Change-Id: I1ffc907f7d0fb93b3e987fe5ff9c6fa5cae00d7f
Reviewed-on: https://go-review.googlesource.com/c/go/+/329309
Trust: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>
This commit is contained in:
Robert Griesemer 2021-06-17 17:49:15 -07:00
parent f503740ccf
commit 4b5fdb0b7a
17 changed files with 205 additions and 186 deletions
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2
src/cmd/compile/internal/types2/builtins.go
View File

@ -783,7 +783,7 @@ func (check *Checker) applyTypeFunc(f func(Type) Type, x Type) Type {
tpar := NewTypeName(nopos, check.pkg, "<type parameter>", nil)
ptyp := check.NewTypeParam(tpar, 0, &emptyInterface) // assigns type to tpar as a side-effect
tsum := newUnion(rtypes, tildes)
ptyp.bound = &Interface{allMethods: markComplete, allTypes: tsum}
ptyp.bound = &Interface{complete: true, tset: &TypeSet{types: tsum}}
return ptyp
}

1
src/cmd/compile/internal/types2/call.go
View File

@ -99,7 +99,6 @@ func (check *Checker) callExpr(x *operand, call *syntax.CallExpr) exprKind {
check.expr(x, call.ArgList[0])
if x.mode != invalid {
if t := asInterface(T); t != nil {
check.completeInterface(nopos, t)
if t.IsConstraint() {
check.errorf(call, "cannot use interface %s in conversion (contains type list or is comparable)", T)
break

1
src/cmd/compile/internal/types2/expr.go
View File

@ -735,7 +735,6 @@ func (check *Checker) implicitTypeAndValue(x *operand, target Type) (Type, const
// Update operand types to the default type rather than the target
// (interface) type: values must have concrete dynamic types.
// Untyped nil was handled upfront.
check.completeInterface(nopos, t)
if !t.Empty() {
return nil, nil, _InvalidUntypedConversion // cannot assign untyped values to non-empty interfaces
}

27
src/cmd/compile/internal/types2/infer.go
View File

@ -321,24 +321,13 @@ func (w *tpWalker) isParameterized(typ Type) (res bool) {
return w.isParameterized(t.params) || w.isParameterized(t.results)
case *Interface:
if t.allMethods != nil {
// interface is complete - quick test
for _, m := range t.allMethods {
if w.isParameterized(m.typ) {
return true
}
tset := t.typeSet()
for _, m := range tset.methods {
if w.isParameterized(m.typ) {
return true
}
return w.isParameterized(t.allTypes)
}
return t.iterate(func(t *Interface) bool {
for _, m := range t.methods {
if w.isParameterized(m.typ) {
return true
}
}
return w.isParameterizedList(t.embeddeds)
}, nil)
return w.isParameterized(tset.types)
case *Map:
return w.isParameterized(t.key) || w.isParameterized(t.elem)
@ -476,15 +465,15 @@ func (check *Checker) inferB(tparams []*TypeName, targs []Type, report bool) (ty
// structuralType returns the structural type of a constraint, if any.
func (check *Checker) structuralType(constraint Type) Type {
if iface, _ := under(constraint).(*Interface); iface != nil {
check.completeInterface(nopos, iface)
if u, _ := iface.allTypes.(*Union); u != nil {
types := iface.typeSet().types
if u, _ := types.(*Union); u != nil {
if u.NumTerms() == 1 {
// TODO(gri) do we need to respect tilde?
return u.types[0]
}
return nil
}
return iface.allTypes
return types
}
return nil
}

64
src/cmd/compile/internal/types2/interface.go
View File

@ -95,9 +95,13 @@ func (check *Checker) interfaceType(ityp *Interface, iface *syntax.InterfaceType
check.posMap[ityp] = append(check.posMap[ityp], tlist[0].(*syntax.Operation).X.Pos())
}
// All methods and embedded elements for this interface are collected;
// i.e., this interface is may be used in a type set computation.
ityp.complete = true
if len(ityp.methods) == 0 && len(ityp.embeddeds) == 0 {
// empty interface
ityp.allMethods = markComplete
ityp.tset = &topTypeSet
return
}
@ -105,7 +109,10 @@ func (check *Checker) interfaceType(ityp *Interface, iface *syntax.InterfaceType
sortMethods(ityp.methods)
sortTypes(ityp.embeddeds)
check.later(func() { check.completeInterface(iface.Pos(), ityp) })
// Compute type set with a non-nil *Checker as soon as possible
// to report any errors. Subsequent uses of type sets should be
// using this computed type set and won't need to pass in a *Checker.
check.later(func() { newTypeSet(check, iface.Pos(), ityp) })
}
func flattenUnion(list []syntax.Expr, x syntax.Expr) []syntax.Expr {
@ -116,26 +123,27 @@ func flattenUnion(list []syntax.Expr, x syntax.Expr) []syntax.Expr {
return append(list, x)
}
func (check *Checker) completeInterface(pos syntax.Pos, ityp *Interface) {
if ityp.allMethods != nil {
return
// newTypeSet may be called with check == nil.
// TODO(gri) move this function into typeset.go eventually
func newTypeSet(check *Checker, pos syntax.Pos, ityp *Interface) *TypeSet {
if ityp.tset != nil {
return ityp.tset
}
// completeInterface may be called via the LookupFieldOrMethod,
// MissingMethod, Identical, or IdenticalIgnoreTags external API
// in which case check will be nil. In this case, type-checking
// must be finished and all interfaces should have been completed.
if check == nil {
panic("internal error: incomplete interface")
// If the interface is not fully set up yet, the type set will
// not be complete, which may lead to errors when using the the
// type set (e.g. missing method). Don't compute a partial type
// set (and don't store it!), so that we still compute the full
// type set eventually. Instead, return the top type set and
// let any follow-on errors play out.
//
// TODO(gri) Consider recording when this happens and reporting
// it as an error (but only if there were no other errors so to
// to not have unnecessary follow-on errors).
if !ityp.complete {
return &topTypeSet
}
completeInterface(check, pos, ityp)
}
// completeInterface may be called with check == nil.
func completeInterface(check *Checker, pos syntax.Pos, ityp *Interface) {
assert(ityp.allMethods == nil)
if check != nil && check.conf.Trace {
// Types don't generally have position information.
// If we don't have a valid pos provided, try to use
@ -144,11 +152,11 @@ func completeInterface(check *Checker, pos syntax.Pos, ityp *Interface) {
pos = ityp.methods[0].pos
}
check.trace(pos, "complete %s", ityp)
check.trace(pos, "type set for %s", ityp)
check.indent++
defer func() {
check.indent--
check.trace(pos, "=> %s (methods = %v, types = %v)", ityp, ityp.allMethods, ityp.allTypes)
check.trace(pos, "=> %s ", ityp.typeSet())
}()
}
@ -157,7 +165,7 @@ func completeInterface(check *Checker, pos syntax.Pos, ityp *Interface) {
// have valid interfaces. Mark the interface as complete to avoid
// infinite recursion if the validType check occurs later for some
// reason.
ityp.allMethods = markComplete
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
@ -231,13 +239,11 @@ func completeInterface(check *Checker, pos syntax.Pos, ityp *Interface) {
var types Type
switch t := under(typ).(type) {
case *Interface:
if t.allMethods == nil {
completeInterface(check, pos, t)
}
for _, m := range t.allMethods {
tset := newTypeSet(check, pos, t)
for _, m := range tset.methods {
addMethod(pos, m, false) // use embedding position pos rather than m.pos
}
types = t.allTypes
types = tset.types
case *Union:
// TODO(gri) combine with default case once we have
// converted all tests to new notation and we
@ -274,9 +280,11 @@ func completeInterface(check *Checker, pos syntax.Pos, ityp *Interface) {
if methods != nil {
sortMethods(methods)
ityp.allMethods = methods
ityp.tset.methods = methods
}
ityp.allTypes = allTypes
ityp.tset.types = allTypes
return ityp.tset
}
func sortTypes(list []Type) {

17
src/cmd/compile/internal/types2/lookup.go
View File

@ -182,9 +182,7 @@ func (check *Checker) rawLookupFieldOrMethod(T Type, addressable bool, pkg *Pack
case *Interface:
// look for a matching method
// TODO(gri) t.allMethods is sorted - use binary search
check.completeInterface(nopos, t)
if i, m := lookupMethod(t.allMethods, pkg, name); m != nil {
if i, m := t.typeSet().LookupMethod(pkg, name); m != nil {
assert(m.typ != nil)
index = concat(e.index, i)
if obj != nil || e.multiples {
@ -195,7 +193,7 @@ func (check *Checker) rawLookupFieldOrMethod(T Type, addressable bool, pkg *Pack
}
case *TypeParam:
if i, m := lookupMethod(t.Bound().allMethods, pkg, name); m != nil {
if i, m := t.Bound().typeSet().LookupMethod(pkg, name); m != nil {
assert(m.typ != nil)
index = concat(e.index, i)
if obj != nil || e.multiples {
@ -307,18 +305,15 @@ func MissingMethod(V Type, T *Interface, static bool) (method *Func, wrongType b
// To improve error messages, also report the wrong signature
// when the method exists on *V instead of V.
func (check *Checker) missingMethod(V Type, T *Interface, static bool) (method, wrongType *Func) {
check.completeInterface(nopos, T)
// fast path for common case
if T.Empty() {
return
}
if ityp := asInterface(V); ityp != nil {
check.completeInterface(nopos, ityp)
// TODO(gri) allMethods is sorted - can do this more efficiently
for _, m := range T.allMethods {
_, f := lookupMethod(ityp.allMethods, m.pkg, m.name)
// TODO(gri) the methods are sorted - could do this more efficiently
for _, m := range T.typeSet().methods {
_, f := ityp.typeSet().LookupMethod(m.pkg, m.name)
if f == nil {
// if m is the magic method == we're ok (interfaces are comparable)
@ -356,7 +351,7 @@ func (check *Checker) missingMethod(V Type, T *Interface, static bool) (method,
// A concrete type implements T if it implements all methods of T.
Vd, _ := deref(V)
Vn := asNamed(Vd)
for _, m := range T.allMethods {
for _, m := range T.typeSet().methods {
// TODO(gri) should this be calling lookupFieldOrMethod instead (and why not)?
obj, _, _ := check.rawLookupFieldOrMethod(V, false, m.pkg, m.name)

12
src/cmd/compile/internal/types2/predicates.go
View File

@ -287,16 +287,8 @@ func (check *Checker) identical0(x, y Type, cmpTags bool, p *ifacePair) bool {
// the same names and identical function types. Lower-case method names from
// different packages are always different. The order of the methods is irrelevant.
if y, ok := y.(*Interface); ok {
// If identical0 is called (indirectly) via an external API entry point
// (such as Identical, IdenticalIgnoreTags, etc.), check is nil. But in
// that case, interfaces are expected to be complete and lazy completion
// here is not needed.
if check != nil {
check.completeInterface(nopos, x)
check.completeInterface(nopos, y)
}
a := x.allMethods
b := y.allMethods
a := x.typeSet().methods
b := y.typeSet().methods
if len(a) == len(b) {
// Interface types are the only types where cycles can occur
// that are not "terminated" via named types; and such cycles

8
src/cmd/compile/internal/types2/sanitize.go
View File

@ -112,9 +112,11 @@ func (s sanitizer) typ(typ Type) Type {
case *Interface:
s.funcList(t.methods)
s.typeList(t.embeddeds)
s.funcList(t.allMethods)
if allTypes := s.typ(t.allTypes); allTypes != t.allTypes {
t.allTypes = allTypes
// TODO(gri) do we need to sanitize type sets?
tset := t.typeSet()
s.funcList(tset.methods)
if types := s.typ(tset.types); types != tset.types {
tset.types = types
}
case *Map:

3
src/cmd/compile/internal/types2/sizeof_test.go
View File

@ -28,7 +28,7 @@ func TestSizeof(t *testing.T) {
{Tuple{}, 12, 24},
{Signature{}, 44, 88},
{Union{}, 24, 48},
{Interface{}, 52, 104},
{Interface{}, 40, 80},
{Map{}, 16, 32},
{Chan{}, 12, 24},
{Named{}, 84, 160},
@ -49,6 +49,7 @@ func TestSizeof(t *testing.T) {
// Misc
{Scope{}, 56, 96},
{Package{}, 40, 80},
{TypeSet{}, 20, 40},
}
for _, test := range tests {

15
src/cmd/compile/internal/types2/subst.go
View File

@ -136,6 +136,7 @@ func (check *Checker) instantiate(pos syntax.Pos, typ Type, targs []Type, poslis
// satisfies reports whether the type argument targ satisfies the constraint of type parameter
// parameter tpar (after any of its type parameters have been substituted through smap).
// A suitable error is reported if the result is false.
// TODO(gri) This should be a method of interfaces or type sets.
func (check *Checker) satisfies(pos syntax.Pos, targ Type, tpar *TypeParam, smap *substMap) bool {
iface := tpar.Bound()
if iface.Empty() {
@ -150,8 +151,7 @@ func (check *Checker) satisfies(pos syntax.Pos, targ Type, tpar *TypeParam, smap
// targ must implement iface (methods)
// - check only if we have methods
check.completeInterface(nopos, iface)
if len(iface.allMethods) > 0 {
if iface.NumMethods() > 0 {
// If the type argument is a pointer to a type parameter, the type argument's
// method set is empty.
// TODO(gri) is this what we want? (spec question)
@ -182,7 +182,7 @@ func (check *Checker) satisfies(pos syntax.Pos, targ Type, tpar *TypeParam, smap
}
// targ's underlying type must also be one of the interface types listed, if any
if iface.allTypes == nil {
if iface.typeSet().types == nil {
return true // nothing to do
}
@ -190,7 +190,7 @@ func (check *Checker) satisfies(pos syntax.Pos, targ Type, tpar *TypeParam, smap
// list of iface types (i.e., the targ type list must be a non-empty subset of the iface types).
if targ := asTypeParam(targ); targ != nil {
targBound := targ.Bound()
if targBound.allTypes == nil {
if targBound.typeSet().types == nil {
check.softErrorf(pos, "%s does not satisfy %s (%s has no type constraints)", targ, tpar.bound, targ)
return false
}
@ -198,7 +198,7 @@ func (check *Checker) satisfies(pos syntax.Pos, targ Type, tpar *TypeParam, smap
// TODO(gri) incorporate tilde information!
if !iface.isSatisfiedBy(typ) {
// TODO(gri) match this error message with the one below (or vice versa)
check.softErrorf(pos, "%s does not satisfy %s (%s type constraint %s not found in %s)", targ, tpar.bound, targ, typ, iface.allTypes)
check.softErrorf(pos, "%s does not satisfy %s (%s type constraint %s not found in %s)", targ, tpar.bound, targ, typ, iface.typeSet().types)
return false
}
return true
@ -207,7 +207,7 @@ func (check *Checker) satisfies(pos syntax.Pos, targ Type, tpar *TypeParam, smap
// Otherwise, targ's type or underlying type must also be one of the interface types listed, if any.
if !iface.isSatisfiedBy(targ) {
check.softErrorf(pos, "%s does not satisfy %s (%s not found in %s)", targ, tpar.bound, targ, iface.allTypes)
check.softErrorf(pos, "%s does not satisfy %s (%s not found in %s)", targ, tpar.bound, targ, iface.typeSet().types)
return false
}
@ -312,12 +312,11 @@ func (subst *subster) typ(typ Type) Type {
methods, mcopied := subst.funcList(t.methods)
embeddeds, ecopied := subst.typeList(t.embeddeds)
if mcopied || ecopied {
iface := &Interface{methods: methods, embeddeds: embeddeds}
iface := &Interface{methods: methods, embeddeds: embeddeds, complete: t.complete}
if subst.check == nil {
panic("internal error: cannot instantiate interfaces yet")
}
subst.check.posMap[iface] = subst.check.posMap[t] // satisfy completeInterface requirement
subst.check.completeInterface(nopos, iface)
return iface
}

15
src/cmd/compile/internal/types2/testdata/check/cycles4.src vendored
View File

@ -4,6 +4,8 @@
package p
import "unsafe"
// Check that all methods of T are collected before
// determining the result type of m (which embeds
// all methods of T).
@ -13,7 +15,7 @@ type T interface {
E
}
var _ = T.m(nil).m().e()
var _ int = T.m(nil).m().e()
type E interface {
e() int
@ -22,7 +24,7 @@ type E interface {
// Check that unresolved forward chains are followed
// (see also comment in resolver.go, checker.typeDecl).
var _ = C.m(nil).m().e()
var _ int = C.m(nil).m().e()
type A B
@ -108,3 +110,12 @@ type Element interface {
type Event interface {
Target() Element
}
// Check that accessing an interface method too early doesn't lead
// to follow-on errors due to an incorrectly computed type set.
type T8 interface {
m() [unsafe.Sizeof(T8.m /* ERROR undefined */ )]int
}
var _ = T8.m // no error expected here

119
src/cmd/compile/internal/types2/type.go
View File

@ -264,18 +264,20 @@ func (s *Signature) Variadic() bool { return s.variadic }
// An Interface represents an interface type.
type Interface struct {
obj Object // type name object defining this interface; or nil (for better error messages)
methods []*Func // ordered list of explicitly declared methods
embeddeds []Type // ordered list of explicitly embedded types
embeddeds []Type // ordered list of explicitly embedded elements
complete bool // indicates that obj, methods, and embeddeds are set and type set can be computed
allMethods []*Func // ordered list of methods declared with or embedded in this interface (TODO(gri): replace with mset)
allTypes Type // intersection of all embedded and locally declared types (TODO(gri) need better field name)
obj Object // type declaration defining this interface; or nil (for better error messages)
tset *TypeSet // type set described by this interface, computed lazily
}
// typeSet returns the type set for interface t.
func (t *Interface) typeSet() *TypeSet { return newTypeSet(nil, nopos, t) }
// is reports whether interface t represents types that all satisfy f.
func (t *Interface) is(f func(Type, bool) bool) bool {
switch t := t.allTypes.(type) {
switch t := t.typeSet().types.(type) {
case nil, *top:
// TODO(gri) should settle on top or nil to represent this case
return false // we must have at least one type! (was bug)
@ -286,21 +288,14 @@ func (t *Interface) is(f func(Type, bool) bool) bool {
}
}
// emptyInterface represents the empty (completed) interface
var emptyInterface = Interface{allMethods: markComplete}
// emptyInterface represents the empty interface
var emptyInterface = Interface{complete: true, tset: &topTypeSet}
// markComplete is used to mark an empty interface as completely
// set up by setting the allMethods field to a non-nil empty slice.
var markComplete = make([]*Func, 0)
// NewInterface returns a new (incomplete) interface for the given methods and embedded types.
// Each embedded type must have an underlying type of interface type.
// NewInterface takes ownership of the provided methods and may modify their types by setting
// missing receivers. To compute the method set of the interface, Complete must be called.
// NewInterface returns a new interface for the given methods and embedded types.
// NewInterface takes ownership of the provided methods and may modify their types
// by setting missing receivers.
//
// Deprecated: Use NewInterfaceType instead which allows any (even non-defined) interface types
// to be embedded. This is necessary for interfaces that embed alias type names referring to
// non-defined (literal) interface types.
// Deprecated: Use NewInterfaceType instead which allows arbitrary embedded types.
func NewInterface(methods []*Func, embeddeds []*Named) *Interface {
tnames := make([]Type, len(embeddeds))
for i, t := range embeddeds {
@ -309,9 +304,9 @@ func NewInterface(methods []*Func, embeddeds []*Named) *Interface {
return NewInterfaceType(methods, tnames)
}
// NewInterfaceType returns a new (incomplete) interface for the given methods and embedded types.
// NewInterfaceType takes ownership of the provided methods and may modify their types by setting
// missing receivers. To compute the method set of the interface, Complete must be called.
// NewInterfaceType returns a new interface for the given methods and embedded types.
// NewInterfaceType takes ownership of the provided methods and may modify their types
// by setting missing receivers.
func NewInterfaceType(methods []*Func, embeddeds []Type) *Interface {
if len(methods) == 0 && len(embeddeds) == 0 {
return &emptyInterface
@ -331,6 +326,8 @@ func NewInterfaceType(methods []*Func, embeddeds []Type) *Interface {
typ.methods = methods
typ.embeddeds = embeddeds
typ.complete = true
return typ
}
@ -354,72 +351,27 @@ func (t *Interface) Embedded(i int) *Named { tname, _ := t.embeddeds[i].(*Named)
func (t *Interface) EmbeddedType(i int) Type { return t.embeddeds[i] }
// NumMethods returns the total number of methods of interface t.
// The interface must have been completed.
func (t *Interface) NumMethods() int { t.Complete(); return len(t.allMethods) }
func (t *Interface) NumMethods() int { return t.typeSet().NumMethods() }
// Method returns the i'th method of interface t for 0 <= i < t.NumMethods().
// The methods are ordered by their unique Id.
// The interface must have been completed.
func (t *Interface) Method(i int) *Func { t.Complete(); return t.allMethods[i] }
func (t *Interface) Method(i int) *Func { return t.typeSet().Method(i) }
// Empty reports whether t is the empty interface.
func (t *Interface) Empty() bool {
t.Complete()
return len(t.allMethods) == 0 && t.allTypes == nil
}
// HasTypeList reports whether interface t has a type list, possibly from an embedded type.
func (t *Interface) HasTypeList() bool {
t.Complete()
return t.allTypes != nil
}
func (t *Interface) Empty() bool { return t.typeSet().IsTop() }
// IsComparable reports whether interface t is or embeds the predeclared interface "comparable".
func (t *Interface) IsComparable() bool {
t.Complete()
_, m := lookupMethod(t.allMethods, nil, "==")
return m != nil
}
func (t *Interface) IsComparable() bool { return t.typeSet().IsComparable() }
// IsConstraint reports t.HasTypeList() || t.IsComparable().
func (t *Interface) IsConstraint() bool {
return t.HasTypeList() || t.IsComparable()
}
// iterate calls f with t and then with any embedded interface of t, recursively, until f returns true.
// iterate reports whether any call to f returned true.
// TODO(gri) This is now only used by infer.go - see if we can eliminate it.
func (t *Interface) iterate(f func(*Interface) bool, seen map[*Interface]bool) bool {
if f(t) {
return true
}
for _, e := range t.embeddeds {
// e should be an interface but be careful (it may be invalid)
if e := asInterface(e); e != nil {
// Cyclic interfaces such as "type E interface { E }" are not permitted
// but they are still constructed and we need to detect such cycles.
if seen[e] {
continue
}
if seen == nil {
seen = make(map[*Interface]bool)
}
seen[e] = true
if e.iterate(f, seen) {
return true
}
}
}
return false
}
// IsConstraint reports whether interface t is not just a method set.
func (t *Interface) IsConstraint() bool { return !t.typeSet().IsMethodSet() }
// isSatisfiedBy reports whether interface t's type list is satisfied by the type typ.
// If the type list is empty (absent), typ trivially satisfies the interface.
// TODO(gri) This is not a great name. Eventually, we should have a more comprehensive
// "implements" predicate.
func (t *Interface) isSatisfiedBy(typ Type) bool {
t.Complete()
switch t := t.allTypes.(type) {
switch t := t.typeSet().types.(type) {
case nil:
return true // no type restrictions
case *Union:
@ -430,15 +382,22 @@ func (t *Interface) isSatisfiedBy(typ Type) bool {
}
}
// Complete computes the interface's method set. It must be called by users of
// Complete computes the interface's type set. It must be called by users of
// NewInterfaceType and NewInterface after the interface's embedded types are
// fully defined and before using the interface type in any way other than to
// form other types. The interface must not contain duplicate methods or a
// panic occurs. Complete returns the receiver.
//
// Deprecated: Type sets are now computed lazily, on demand; this function
// is only here for backward-compatibility. It does not have to
// be called explicitly anymore.
func (t *Interface) Complete() *Interface {
if t.allMethods == nil {
completeInterface(nil, nopos, t)
}
// Some tests are still depending on the state change
// (string representation of an Interface not containing an
// /* incomplete */ marker) caused by the explicit Complete
// call, so we compute the type set eagerly here.
t.complete = true
t.typeSet()
return t
}
@ -674,7 +633,7 @@ func (t *TypeParam) Bound() *Interface {
pos = n.obj.pos
}
// TODO(gri) switch this to an unexported method on Checker.
t.check.completeInterface(pos, iface)
newTypeSet(t.check, pos, iface)
return iface
}
@ -700,7 +659,7 @@ func optype(typ Type) Type {
// for a type parameter list of the form:
// (type T interface { type T }).
// See also issue #39680.
if a := t.Bound().allTypes; a != nil {
if a := t.Bound().typeSet().types; a != nil {
// If we have a union with a single entry, ignore
// any tilde because under(~t) == under(t).
if u, _ := a.(*Union); u != nil && u.NumTerms() == 1 {

70
src/cmd/compile/internal/types2/typeset.go Normal file
View File

@ -0,0 +1,70 @@
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package types2
import (
"bytes"
)
// topTypeSet may be used as type set for the empty interface.
var topTypeSet TypeSet
// A TypeSet represents the type set of an interface.
type TypeSet struct {
// TODO(gri) consider using a set for the methods for faster lookup
methods []*Func // all methods of the interface; sorted by unique ID
types Type // typically a *Union; nil means no type restrictions
}
func (s *TypeSet) String() string {
if s.IsTop() {
return "⊤"
}
var buf bytes.Buffer
buf.WriteByte('{')
for i, m := range s.methods {
if i > 0 {
buf.WriteByte(';')
}
buf.WriteByte(' ')
buf.WriteString(m.String())
}
if len(s.methods) > 0 && s.types != nil {
buf.WriteByte(';')
}
if s.types != nil {
buf.WriteByte(' ')
writeType(&buf, s.types, nil, nil)
}
buf.WriteString(" }") // there was a least one method or type
return buf.String()
}
// IsTop reports whether type set s is the top type set (corresponding to the empty interface).
func (s *TypeSet) IsTop() bool { return 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.types == nil && !s.IsComparable() }
// IsComparable reports whether each type in the set is comparable.
func (s *TypeSet) IsComparable() bool {
_, m := s.LookupMethod(nil, "==")
return m != nil
}
// NumMethods returns the number of methods available.
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] }
// 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) {
// TODO(gri) s.methods is sorted - consider binary search
return lookupMethod(s.methods, pkg, name)
}

13
src/cmd/compile/internal/types2/typestring.go
View File

@ -189,7 +189,8 @@ func writeType(buf *bytes.Buffer, typ Type, qf Qualifier, visited []Type) {
if gcCompatibilityMode {
// print flattened interface
// (useful to compare against gc-generated interfaces)
for i, m := range t.allMethods {
tset := t.typeSet()
for i, m := range tset.methods {
if i > 0 {
buf.WriteString("; ")
}
@ -197,12 +198,12 @@ func writeType(buf *bytes.Buffer, typ Type, qf Qualifier, visited []Type) {
writeSignature(buf, m.typ.(*Signature), qf, visited)
empty = false
}
if !empty && t.allTypes != nil {
if !empty && tset.types != nil {
buf.WriteString("; ")
}
if t.allTypes != nil {
if tset.types != nil {
buf.WriteString("type ")
writeType(buf, t.allTypes, qf, visited)
writeType(buf, tset.types, qf, visited)
}
} else {
// print explicit interface methods and embedded types
@ -225,7 +226,9 @@ func writeType(buf *bytes.Buffer, typ Type, qf Qualifier, visited []Type) {
empty = false
}
}
if debug && (t.allMethods == nil || len(t.methods) > len(t.allMethods)) {
// print /* incomplete */ if needed to satisfy existing tests
// TODO(gri) get rid of this eventually
if debug && t.tset == nil {
if !empty {
buf.WriteByte(' ')
}

8
src/cmd/compile/internal/types2/typexpr.go
View File

@ -141,12 +141,12 @@ func (check *Checker) ordinaryType(pos syntax.Pos, typ Type) {
// interface methods. Delay this check to the end of type-checking.
check.later(func() {
if t := asInterface(typ); t != nil {
check.completeInterface(pos, t) // TODO(gri) is this the correct position?
if t.allTypes != nil {
check.softErrorf(pos, "interface contains type constraints (%s)", t.allTypes)
tset := newTypeSet(check, pos, t) // TODO(gri) is this the correct position?
if tset.types != nil {
check.softErrorf(pos, "interface contains type constraints (%s)", tset.types)
return
}
if t.IsComparable() {
if tset.IsComparable() {
check.softErrorf(pos, "interface is (or embeds) comparable")
}
}

12
src/cmd/compile/internal/types2/unify.go
View File

@ -361,16 +361,8 @@ func (u *unifier) nify(x, y Type, p *ifacePair) bool {
// the same names and identical function types. Lower-case method names from
// different packages are always different. The order of the methods is irrelevant.
if y, ok := y.(*Interface); ok {
// If identical0 is called (indirectly) via an external API entry point
// (such as Identical, IdenticalIgnoreTags, etc.), check is nil. But in
// that case, interfaces are expected to be complete and lazy completion
// here is not needed.
if u.check != nil {
u.check.completeInterface(nopos, x)
u.check.completeInterface(nopos, y)
}
a := x.allMethods
b := y.allMethods
a := x.typeSet().methods
b := y.typeSet().methods
if len(a) == len(b) {
// Interface types are the only types where cycles can occur
// that are not "terminated" via named types; and such cycles

4
src/cmd/compile/internal/types2/universe.go
View File

@ -88,7 +88,7 @@ func defPredeclaredTypes() {
res := NewVar(nopos, nil, "", Typ[String])
sig := &Signature{results: NewTuple(res)}
err := NewFunc(nopos, nil, "Error", sig)
typ := &Named{underlying: NewInterfaceType([]*Func{err}, nil).Complete()}
typ := &Named{underlying: NewInterfaceType([]*Func{err}, nil)}
sig.recv = NewVar(nopos, nil, "", typ)
def(NewTypeName(nopos, nil, "error", typ))
}
@ -216,7 +216,7 @@ func defPredeclaredComparable() {
// set up later to match the usual interface method assumptions.
sig := new(Signature)
eql := NewFunc(nopos, nil, "==", sig)
iface := NewInterfaceType([]*Func{eql}, nil).Complete()
iface := NewInterfaceType([]*Func{eql}, nil)
// set up the defined type for the interface
obj := NewTypeName(nopos, nil, "comparable", nil)