mirror of
https://github.com/golang/go
synced 2024-09-04 23:44:16 +00:00
[dev.typeparams] go/types: recursive substitution must terminate (bug fix)
This is a port of CL 333383 to go/types. Change-Id: I7ff68116cbe63337dbcc834c473a2a5588274e36 Reviewed-on: https://go-review.googlesource.com/c/go/+/335115 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:
parent
c7c13ae432
commit
43ad1ffa99
|
@ -1817,3 +1817,26 @@ func f(x T) T { return foo.F(x) }
|
|||
}
|
||||
}
|
||||
}
|
||||
|
||||
func TestInstantiate(t *testing.T) {
|
||||
// eventually we like more tests but this is a start
|
||||
const src = genericPkg + "p; type T[P any] *T[P]"
|
||||
pkg, err := pkgFor(".", src, nil)
|
||||
if err != nil {
|
||||
t.Fatal(err)
|
||||
}
|
||||
|
||||
// type T should have one type parameter
|
||||
T := pkg.Scope().Lookup("T").Type().(*Named)
|
||||
if n := len(T.TParams()); n != 1 {
|
||||
t.Fatalf("expected 1 type parameter; found %d", n)
|
||||
}
|
||||
|
||||
// instantiation should succeed (no endless recursion)
|
||||
res := Instantiate(token.NoPos, T, []Type{Typ[Int]})
|
||||
|
||||
// instantiated type should point to itself
|
||||
if res.Underlying().(*Pointer).Elem() != res {
|
||||
t.Fatalf("unexpected result type: %s", res)
|
||||
}
|
||||
}
|
||||
|
|
|
@ -237,15 +237,27 @@ func (check *Checker) subst(pos token.Pos, typ Type, smap *substMap) Type {
|
|||
}
|
||||
|
||||
// general case
|
||||
subst := subster{check, pos, make(map[Type]Type), smap}
|
||||
var subst subster
|
||||
subst.pos = pos
|
||||
subst.smap = smap
|
||||
if check != nil {
|
||||
subst.check = check
|
||||
subst.typMap = check.typMap
|
||||
} else {
|
||||
// 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)
|
||||
}
|
||||
return subst.typ(typ)
|
||||
}
|
||||
|
||||
type subster struct {
|
||||
check *Checker
|
||||
pos token.Pos
|
||||
cache map[Type]Type
|
||||
smap *substMap
|
||||
check *Checker // nil if called via Instantiate
|
||||
typMap map[string]*Named
|
||||
}
|
||||
|
||||
func (subst *subster) typ(typ Type) Type {
|
||||
|
@ -390,22 +402,16 @@ func (subst *subster) typ(typ Type) Type {
|
|||
// before creating a new named type, check if we have this one already
|
||||
h := instantiatedHash(t, newTargs)
|
||||
dump(">>> new type hash: %s", h)
|
||||
if subst.check != nil {
|
||||
if named, found := subst.check.typMap[h]; found {
|
||||
if named, found := subst.typMap[h]; found {
|
||||
dump(">>> found %s", named)
|
||||
subst.cache[t] = named
|
||||
return named
|
||||
}
|
||||
}
|
||||
|
||||
// create a new named type and populate caches to avoid endless recursion
|
||||
// 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
|
||||
named.targs = newTargs
|
||||
if subst.check != nil {
|
||||
subst.check.typMap[h] = named
|
||||
}
|
||||
subst.cache[t] = named
|
||||
subst.typMap[h] = named
|
||||
|
||||
// do the substitution
|
||||
dump(">>> subst %s with %s (new: %s)", t.underlying, subst.smap, newTargs)
|
||||
|
|
Loading…
Reference in a new issue