This is a straightforward port of CL 341855 to go/types.
Change-Id: I42a74df7a54f5d03aab31ad75dfeb3d1ba775354
Reviewed-on: https://go-review.googlesource.com/c/go/+/342477
Trust: Robert Findley <rfindley@google.com>
Run-TryBot: Robert Findley <rfindley@google.com>
Reviewed-by: Robert Griesemer <gri@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
res := check.Instantiate(token.NoPos, T, []Type{Typ[Int]}, nil, false)
// instantiated type should point to itself
- if res.Underlying().(*Pointer).Elem() != res {
- t.Fatalf("unexpected result type: %s", res)
+ if p := res.Underlying().(*Pointer).Elem(); p != res {
+ t.Fatalf("unexpected result type: %s points to %s", res, p)
}
}
// 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().list(), targs)).(*Tuple)
+ sigParams = check.subst(call.Pos(), sigParams, makeSubstMap(sig.TParams().list(), targs), nil).(*Tuple)
} else {
sigParams = rsig.params
}
// (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().list(), targs))
+ copy.typ = check.subst(e.Pos(), m.typ, makeSubstMap(sig.RParams().list(), targs), nil)
obj = ©
}
// TODO(gri) we also need to do substitution for parameterized interface methods
}
case *Named:
- t.expand()
+ t.expand(check.typMap)
// don't touch the type if it is from a different package or the Universe scope
// (doing so would lead to a race condition - was issue #35049)
if t.obj.pkg != check.pkg {
// and field names must be distinct."
base := asNamed(obj.typ) // shouldn't fail but be conservative
if base != nil {
- if t, _ := base.Underlying().(*Struct); t != nil {
+ u := safeUnderlying(base) // base should be expanded, but use safeUnderlying to be conservative
+ if t, _ := u.(*Struct); t != nil {
for _, fld := range t.fields {
if fld.name != "_" {
assert(mset.insert(fld) == nil)
func (check *Checker) convertUntyped(x *operand, target Type) {
newType, val, code := check.implicitTypeAndValue(x, target)
if code != 0 {
- check.invalidConversion(code, x, target.Underlying())
+ check.invalidConversion(code, x, safeUnderlying(target))
x.mode = invalid
return
}
// but that doesn't impact the isParameterized check for now).
if params.Len() > 0 {
smap := makeSubstMap(tparams, targs)
- params = check.subst(token.NoPos, params, smap).(*Tuple)
+ params = check.subst(token.NoPos, params, smap, nil).(*Tuple)
}
// --- 2 ---
}
smap := makeSubstMap(tparams, targs)
// TODO(rFindley): pass a positioner here, rather than arg.Pos().
- inferred := check.subst(arg.Pos(), tpar, smap)
+ inferred := check.subst(arg.Pos(), tpar, smap, nil)
if inferred != tpar {
check.errorf(arg, _Todo, "%s %s of %s does not match inferred type %s for %s", kind, targ, arg.expr, inferred, tpar)
} else {
n := 0
for _, index := range dirty {
t0 := types[index]
- if t1 := check.subst(token.NoPos, t0, smap); t1 != t0 {
+ if t1 := check.subst(token.NoPos, t0, smap, nil); t1 != t0 {
types[index] = t1
dirty[n] = index
n++
var tparams []*TypeName
switch t := typ.(type) {
case *Named:
- tparams = t.TParams().list()
+ return check.instantiateLazy(pos, t, targs, posList, verify)
case *Signature:
tparams = t.TParams().list()
defer func() {
panic(fmt.Sprintf("%v: cannot instantiate %v", pos, typ))
}
- inst := check.instantiate(pos, typ, tparams, targs, posList)
+ inst := check.instantiate(pos, typ, tparams, targs, posList, nil)
if verify && len(tparams) == len(targs) {
check.verify(pos, tparams, targs, posList)
}
return inst
}
-func (check *Checker) instantiate(pos token.Pos, typ Type, tparams []*TypeName, targs []Type, posList []token.Pos) (res Type) {
+func (check *Checker) instantiate(pos token.Pos, typ Type, tparams []*TypeName, targs []Type, posList []token.Pos, typMap map[string]*Named) (res Type) {
// the number of supplied types must match the number of type parameters
if len(targs) != len(tparams) {
// TODO(gri) provide better error message
// Calling under() here may lead to endless instantiations.
// Test case: type T[P any] T[P]
// TODO(gri) investigate if that's a bug or to be expected.
- under = res.Underlying()
+ under = safeUnderlying(res)
}
check.trace(pos, "=> %s (under = %s)", res, under)
}()
return typ // nothing to do (minor optimization)
}
- smap := makeSubstMap(tparams, targs)
-
- return check.subst(pos, typ, smap)
+ return check.subst(pos, typ, makeSubstMap(tparams, targs), typMap)
}
-// InstantiateLazy is like Instantiate, but avoids actually
-// instantiating the type until needed. typ must be a *Named
-// type.
-func (check *Checker) InstantiateLazy(pos token.Pos, typ Type, targs []Type, posList []token.Pos, verify bool) Type {
- // Don't use asNamed here: we don't want to expand the base during lazy
- // instantiation.
- base := typ.(*Named)
- if base == nil {
- panic(fmt.Sprintf("%v: cannot instantiate %v", pos, typ))
- }
+// instantiateLazy avoids actually instantiating the type until needed. typ
+// must be a *Named type.
+func (check *Checker) instantiateLazy(pos token.Pos, base *Named, targs []Type, posList []token.Pos, verify bool) Type {
if verify && base.TParams().Len() == len(targs) {
+ // TODO: lift the nil check in verify to here.
check.later(func() {
check.verify(pos, base.tparams.list(), targs, posList)
})
// as the instantiated type; before we can use it for bounds checking we
// need to instantiate it with the type arguments with which we instantiate
// the parameterized type.
- iface = check.subst(pos, iface, smap).(*Interface)
+ iface = check.subst(pos, iface, smap, nil).(*Interface)
// if iface is comparable, targ must be comparable
// TODO(gri) the error messages needs to be better, here
// pointer type but discard the result if it is a method since we would
// not have found it for T (see also issue 8590).
if t := asNamed(T); t != nil {
- if p, _ := t.Underlying().(*Pointer); p != nil {
+ if p, _ := safeUnderlying(t).(*Pointer); p != nil {
obj, index, indirect = lookupFieldOrMethod(p, false, pkg, name)
if _, ok := obj.(*Func); ok {
return nil, nil, false
if len(ftyp.RParams().list()) != len(Vn.targs) {
return
}
- ftyp = check.subst(token.NoPos, ftyp, makeSubstMap(ftyp.RParams().list(), Vn.targs)).(*Signature)
+ ftyp = check.subst(token.NoPos, ftyp, makeSubstMap(ftyp.RParams().list(), Vn.targs), nil).(*Signature)
}
// If the methods have type parameters we don't care whether they
}
}
-func (t *Named) Underlying() Type { return t.load().underlying }
+func (t *Named) Underlying() Type { return t.load().expand(nil).underlying }
func (t *Named) String() string { return TypeString(t, nil) }
// ----------------------------------------------------------------------------
// is detected, the result is Typ[Invalid]. If a cycle is detected and
// n0.check != nil, the cycle is reported.
func (n0 *Named) under() Type {
- n0.expand()
+ n0.expand(nil)
- u := n0.Underlying()
+ u := n0.load().underlying
if u == Typ[Invalid] {
return u
seen := map[*Named]int{n0: 0}
path := []Object{n0.obj}
for {
- u = n.Underlying()
+ u = n.load().underlying
if u == nil {
u = Typ[Invalid]
break
var n1 *Named
switch u1 := u.(type) {
case *Named:
- u1.expand()
+ u1.expand(nil)
n1 = u1
}
if n1 == nil {
// expand ensures that the underlying type of n is instantiated.
// The underlying type will be Typ[Invalid] if there was an error.
-// TODO(rfindley): expand would be a better name for this method, but conflicts
-// with the existing concept of lazy expansion. Need to reconcile this.
-func (n *Named) expand() {
+func (n *Named) expand(typMap map[string]*Named) *Named {
if n.instance != nil {
// n must be loaded before instantiation, in order to have accurate
// tparams. This is done implicitly by the call to n.TParams, but making it
// explicit is harmless: load is idempotent.
n.load()
- inst := n.check.instantiate(n.instance.pos, n.orig.underlying, n.TParams().list(), n.targs, n.instance.posList)
+ if typMap == nil {
+ if n.check != nil {
+ typMap = n.check.typMap
+ } 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
+ // typMap, but don't want to create a duplicate of the current instance
+ // in the process of expansion.
+ h := instantiatedHash(n.orig, n.targs)
+ typMap = map[string]*Named{h: n}
+ }
+ }
+
+ inst := n.check.instantiate(n.instance.pos, n.orig.underlying, n.TParams().list(), n.targs, n.instance.posList, typMap)
n.underlying = inst
n.fromRHS = inst
n.instance = nil
}
+ return n
+}
+
+// safeUnderlying returns the underlying of typ without expanding instances, to
+// avoid infinite recursion.
+//
+// TODO(rfindley): eliminate this function or give it a better name.
+func safeUnderlying(typ Type) Type {
+ if t, _ := typ.(*Named); t != nil {
+ return t.load().underlying
+ }
+ return typ.Underlying()
}
// Two named types are identical if their type names originate
// in the same type declaration.
if y, ok := y.(*Named); ok {
- x.expand()
- y.expand()
+ x.expand(nil)
+ y.expand(nil)
// TODO(gri) Why is x == y not sufficient? And if it is,
// we can just return false here because x == y
// is caught in the very beginning of this function.
// TODO(gri) should we assume now that bounds always exist?
// (no bound == empty interface)
if bound != nil {
- bound = check.subst(tname.pos, bound, smap)
+ bound = check.subst(tname.pos, bound, smap, nil)
tname.typ.(*TypeParam).bound = bound
}
}
var err string
switch T := rtyp.(type) {
case *Named:
- T.expand()
+ T.expand(nil)
// spec: "The type denoted by T is called the receiver base type; it must not
// be a pointer or interface type and it must be declared in the same package
// as the method."
// subst is functional in the sense that it doesn't modify the incoming
// type. If a substitution took place, the result type is different from
// from the incoming type.
-func (check *Checker) subst(pos token.Pos, typ Type, smap *substMap) Type {
+//
+// If the given typMap is nil and check is non-nil, check.typMap is used.
+func (check *Checker) subst(pos token.Pos, typ Type, smap *substMap, typMap map[string]*Named) Type {
if smap.empty() {
return typ
}
var subst subster
subst.pos = pos
subst.smap = smap
+
if check != nil {
subst.check = check
- subst.typMap = check.typMap
- } else {
+ if typMap == nil {
+ typMap = check.typMap
+ }
+ }
+ if typMap == nil {
// If we don't have a *Checker and its global type map,
// use a local version. Besides avoiding duplicate work,
// the type map prevents infinite recursive substitution
// for recursive types (example: type T[P any] *T[P]).
- subst.typMap = make(map[string]*Named)
+ typMap = make(map[string]*Named)
}
+ subst.typMap = typMap
return subst.typ(typ)
}
// create a new named type and populate typMap to avoid endless recursion
tname := NewTypeName(subst.pos, t.obj.pkg, t.obj.name, nil)
- named := subst.check.newNamed(tname, t, t.Underlying(), t.TParams(), t.methods) // method signatures are updated lazily
+ t.load()
+ named := subst.check.newNamed(tname, t.orig, t.underlying, t.TParams(), t.methods) // method signatures are updated lazily
named.targs = newTargs
subst.typMap[h] = named
- t.expand() // must happen after typMap update to avoid infinite recursion
+ t.expand(subst.typMap) // must happen after typMap update to avoid infinite recursion
// do the substitution
dump(">>> subst %s with %s (new: %s)", t.underlying, subst.smap, newTargs)
- named.underlying = subst.typOrNil(t.Underlying())
+ named.underlying = subst.typOrNil(t.underlying)
dump(">>> underlying: %v", named.underlying)
assert(named.underlying != nil)
named.fromRHS = named.underlying // for cycle detection (Checker.validType)
func asNamed(t Type) *Named {
e, _ := t.(*Named)
if e != nil {
- e.expand()
+ e.expand(nil)
}
return e
}
// Test case: type T[P any] *T[P]
// TODO(gri) investigate if that's a bug or to be expected
// (see also analogous comment in Checker.instantiate).
- under = T.Underlying()
+ under = safeUnderlying(T)
}
if T == under {
check.trace(e0.Pos(), "=> %s // %s", T, goTypeName(T))
}
func (check *Checker) instantiatedType(x ast.Expr, targsx []ast.Expr, def *Named) Type {
- base := check.genericType(x, true)
- if base == Typ[Invalid] {
- return base // error already reported
+ gtyp := check.genericType(x, true)
+ if gtyp == Typ[Invalid] {
+ return gtyp // error already reported
+ }
+ base, _ := gtyp.(*Named)
+ if base == nil {
+ panic(fmt.Sprintf("%v: cannot instantiate %v", x.Pos(), gtyp))
}
// evaluate arguments
posList[i] = arg.Pos()
}
- typ := check.InstantiateLazy(x.Pos(), base, targs, posList, true)
+ typ := check.instantiateLazy(x.Pos(), base, targs, posList, true)
def.setUnderlying(typ)
// make sure we check instantiation works at least once
// return x.obj == y.obj
// }
if y, ok := y.(*Named); ok {
- x.expand()
- y.expand()
+ x.expand(nil)
+ y.expand(nil)
// TODO(gri) This is not always correct: two types may have the same names
// in the same package if one of them is nested in a function.
// Extremely unlikely but we need an always correct solution.