// methods may not have a fully set up signature yet
if m, _ := obj.(*Func); m != nil {
check.objDecl(m, nil)
- // If m has a parameterized receiver type, infer the type arguments from
- // the actual receiver provided and then substitute the type parameters in
- // the signature accordingly.
- // TODO(gri) factor this code out
- sig := m.typ.(*Signature)
- if sig.RecvTypeParams().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
- // embedded struct or interface that declared the method.
- // Traverse the embedding to find that type (issue #44688).
- recv := x.typ
- for i := 0; i < len(index)-1; i++ {
- // The embedded type is either a struct or a pointer to
- // a struct except for the last one (which we don't need).
- recv = asStruct(derefStructPtr(recv)).Field(index[i]).typ
- }
-
- // The method may have a pointer receiver, but the actually provided receiver
- // may be a (hopefully addressable) non-pointer value, or vice versa. Here we
- // only care about inferring receiver type parameters; to make the inference
- // work, match up pointer-ness of receiver and argument.
- if ptrRecv := isPointer(sig.recv.typ); ptrRecv != isPointer(recv) {
- if ptrRecv {
- recv = NewPointer(recv)
- } else {
- recv = recv.(*Pointer).base
- }
- }
- // Disable reporting of errors during inference below. If we're unable to infer
- // 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.RecvTypeParams().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
- }
- // Don't modify m. Instead - for now - make a copy of m and use that instead.
- // (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.RecvTypeParams().list(), targs), nil)
- obj = ©
- }
- // TODO(gri) we also need to do substitution for parameterized interface methods
- // (this breaks code in testdata/linalg.go2 at the moment)
- // 12/20/2019: Is this TODO still correct?
}
if x.mode == typexpr {
}()
}
+ // Funcs with m.instRecv set have not yet be completed. Complete them now
+ // so that they have a type when objDecl exits.
+ if m, _ := obj.(*Func); m != nil && m.instRecv != nil {
+ check.completeMethod(check.conf.Environment, m)
+ }
+
// Checking the declaration of obj means inferring its type
// (and possibly its value, for constants).
// An object's type (and thus the object) may be in one of
//
// Constraint type inference is used after each step to expand the set of type arguments.
//
+// TODO(rfindley): remove the report parameter: is no longer needed.
func (check *Checker) infer(posn positioner, tparams []*TypeParam, targs []Type, params *Tuple, args []*operand, report bool) (result []Type) {
if debug {
defer func() {
t.Errorf("instance from pkg1 (%s) is identical to instance from pkg2 (%s)", res1, res2)
}
}
+
+func TestMethodInstantiation(t *testing.T) {
+ const prefix = genericPkg + `p
+
+type T[P any] struct{}
+
+var X T[int]
+
+`
+ tests := []struct {
+ decl string
+ want string
+ }{
+ {"func (r T[P]) m() P", "func (T[int]).m() int"},
+ {"func (r T[P]) m(P)", "func (T[int]).m(int)"},
+ {"func (r T[P]) m() func() P", "func (T[int]).m() func() int"},
+ {"func (r T[P]) m() T[P]", "func (T[int]).m() T[int]"},
+ {"func (r T[P]) m(T[P])", "func (T[int]).m(T[int])"},
+ {"func (r T[P]) m(T[P], P, string)", "func (T[int]).m(T[int], int, string)"},
+ {"func (r T[P]) m(T[P], T[string], T[int])", "func (T[int]).m(T[int], T[string], T[int])"},
+ }
+
+ for _, test := range tests {
+ src := prefix + test.decl
+ pkg, err := pkgFor(".", src, nil)
+ if err != nil {
+ t.Fatal(err)
+ }
+ typ := pkg.Scope().Lookup("X").Type().(*Named)
+ obj, _, _ := LookupFieldOrMethod(typ, false, pkg, "m")
+ m, _ := obj.(*Func)
+ if m == nil {
+ t.Fatalf(`LookupFieldOrMethod(%s, "m") = %v, want func m`, typ, obj)
+ }
+ if got := ObjectString(m, RelativeTo(pkg)); got != test.want {
+ t.Errorf("instantiated %q, want %q", got, test.want)
+ }
+ }
+}
package types
-import "go/token"
-
// Internal use of LookupFieldOrMethod: If the obj result is a method
// associated with a concrete (non-interface) type, the method's signature
// may not be fully set up. Call Checker.objDecl(obj, nil) before accessing
}
// A concrete type implements T if it implements all methods of T.
- Vd, _ := deref(V)
- Vn := asNamed(Vd)
for _, m := range T.typeSet().methods {
// TODO(gri) should this be calling lookupFieldOrMethod instead (and why not)?
obj, _, _ := lookupFieldOrMethod(V, false, m.pkg, m.name)
panic("method with type parameters")
}
- // If V is a (instantiated) generic type, its methods are still
- // parameterized using the original (declaration) receiver type
- // parameters (subst simply copies the existing method list, it
- // does not instantiate the methods).
- // 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 && Vn.TypeParams().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.RecvTypeParams().list()) != Vn.targs.Len() {
- return
- }
- ftyp = check.subst(token.NoPos, ftyp, makeSubstMap(ftyp.RecvTypeParams().list(), Vn.targs.list()), nil).(*Signature)
- }
-
// If the methods have type parameters we don't care whether they
// are the same or not, as long as they match up. Use unification
// to see if they can be made to match.
// expandNamed ensures that the underlying type of n is instantiated.
// The underlying type will be Typ[Invalid] if there was an error.
-func expandNamed(env *Environment, n *Named, instPos token.Pos) (*TypeParamList, Type, []*Func) {
+func expandNamed(env *Environment, n *Named, instPos token.Pos) (tparams *TypeParamList, underlying Type, methods []*Func) {
n.orig.resolve(env)
- var u Type
- if n.check.validateTArgLen(instPos, n.orig.tparams.Len(), n.targs.Len()) {
+ check := n.check
+
+ if check.validateTArgLen(instPos, n.orig.tparams.Len(), n.targs.Len()) {
// TODO(rfindley): handling an optional Checker and Environment here (and
// in subst) feels overly complicated. Can we simplify?
if env == nil {
- if n.check != nil {
- env = n.check.conf.Environment
+ if check != nil {
+ env = check.conf.Environment
} else {
// If we're instantiating lazily, we might be outside the scope of a
// type-checking pass. In that case we won't have a pre-existing
env = NewEnvironment()
}
h := env.typeHash(n.orig, n.targs.list())
- // add the instance to the environment to avoid infinite recursion.
- // addInstance may return a different, existing instance, but we
- // shouldn't return that instance from expand.
+ // ensure that an instance is recorded for h to avoid infinite recursion.
env.typeForHash(h, n)
}
- u = n.check.subst(instPos, n.orig.underlying, makeSubstMap(n.orig.tparams.list(), n.targs.list()), env)
+ smap := makeSubstMap(n.orig.tparams.list(), n.targs.list())
+ underlying = n.check.subst(instPos, n.orig.underlying, smap, env)
+ for i := 0; i < n.orig.NumMethods(); i++ {
+ origm := n.orig.Method(i)
+
+ // During type checking origm may not have a fully set up type, so defer
+ // instantiation of its signature until later.
+ m := NewFunc(origm.pos, origm.pkg, origm.name, nil)
+ m.hasPtrRecv = origm.hasPtrRecv
+ // Setting instRecv here allows us to complete later (we need the
+ // instRecv to get targs and the original method).
+ m.instRecv = n
+
+ methods = append(methods, m)
+ }
+ } else {
+ underlying = Typ[Invalid]
+ }
+
+ // Methods should not escape the type checker API without being completed. If
+ // we're in the context of a type checking pass, we need to defer this until
+ // later (not all methods may have types).
+ completeMethods := func() {
+ for _, m := range methods {
+ if m.instRecv != nil {
+ check.completeMethod(env, m)
+ }
+ }
+ }
+ if check != nil {
+ check.later(completeMethods)
} else {
- u = Typ[Invalid]
+ completeMethods()
}
- return n.orig.tparams, u, n.orig.methods
+
+ return n.orig.tparams, underlying, methods
+}
+
+func (check *Checker) completeMethod(env *Environment, m *Func) {
+ assert(m.instRecv != nil)
+ rtyp := m.instRecv
+ m.instRecv = nil
+ m.setColor(black)
+
+ assert(rtyp.TypeArgs().Len() > 0)
+
+ // Look up the original method.
+ _, orig := lookupMethod(rtyp.orig.methods, rtyp.obj.pkg, m.name)
+ assert(orig != nil)
+ if check != nil {
+ check.objDecl(orig, nil)
+ }
+ origSig := orig.typ.(*Signature)
+ if origSig.RecvTypeParams().Len() != rtyp.targs.Len() {
+ m.typ = origSig // or new(Signature), but we can't use Typ[Invalid]: Funcs must have Signature type
+ return // error reported elsewhere
+ }
+
+ smap := makeSubstMap(origSig.RecvTypeParams().list(), rtyp.targs.list())
+ sig := check.subst(orig.pos, origSig, smap, env).(*Signature)
+ sig.recv = NewParam(origSig.recv.pos, origSig.recv.pkg, origSig.recv.name, rtyp)
+
+ m.typ = sig
}
// safeUnderlying returns the underlying of typ without expanding instances, to
// An abstract method may belong to many interfaces due to embedding.
type Func struct {
object
- hasPtrRecv bool // only valid for methods that don't have a type yet
+ instRecv *Named // if non-nil, the receiver type for an incomplete instance method
+ hasPtrRecv bool // only valid for methods that don't have a type yet
}
// NewFunc returns a new function with the given signature, representing
if sig != nil {
typ = sig
}
- return &Func{object{nil, pos, pkg, name, typ, 0, colorFor(typ), token.NoPos}, false}
+ return &Func{object{nil, pos, pkg, name, typ, 0, colorFor(typ), token.NoPos}, nil, false}
}
// FullName returns the package- or receiver-type-qualified name of
{Const{}, 48, 88},
{TypeName{}, 40, 72},
{Var{}, 44, 80},
- {Func{}, 44, 80},
+ {Func{}, 48, 88},
{Label{}, 44, 80},
{Builtin{}, 44, 80},
{Nil{}, 40, 72},
env = NewEnvironment()
}
subst.env = env
-
return subst.typ(typ)
}
if recv != t.recv || params != t.params || results != t.results {
return &Signature{
rparams: t.rparams,
- // TODO(rFindley) why can't we nil out tparams here, rather than in
- // instantiate above?
+ // TODO(rFindley) why can't we nil out tparams here, rather than in instantiate?
tparams: t.tparams,
scope: t.scope,
recv: recv,