go/types: mark implicit interfaces as such
This is a straightforward port of CL 353396 to go/types.
For #48424
Change-Id: I3040c2ad3a8c9573026277de01deb9c47953cec8
Reviewed-on: https://go-review.googlesource.com/c/go/+/354991
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>
diff --git a/src/go/types/decl.go b/src/go/types/decl.go
index c8cac0f..f97fa25 100644
--- a/src/go/types/decl.go
+++ b/src/go/types/decl.go
@@ -715,11 +715,13 @@
wrap = op.Op == token.OR
}
if wrap {
- // TODO(gri) Should mark this interface as "implicit" somehow
- // (and propagate the info to types2.Interface) so
- // that we can elide the interface again in error
- // messages. Could use a sentinel name for the field.
x = &ast.InterfaceType{Methods: &ast.FieldList{List: []*ast.Field{{Type: x}}}}
+ t := check.typ(x)
+ // mark t as implicit interface if all went well
+ if t, _ := t.(*Interface); t != nil {
+ t.implicit = true
+ }
+ return t
}
return check.typ(x)
}
diff --git a/src/go/types/interface.go b/src/go/types/interface.go
index 866a342..2f4f10d 100644
--- a/src/go/types/interface.go
+++ b/src/go/types/interface.go
@@ -19,6 +19,7 @@
methods []*Func // ordered list of explicitly declared methods
embeddeds []Type // ordered list of explicitly embedded elements
embedPos *[]token.Pos // positions of embedded elements; or nil (for error messages) - use pointer to save space
+ implicit bool // interface is wrapper for type set literal (non-interface T, ~T, or A|B)
complete bool // indicates that obj, methods, and embeddeds are set and type set can be computed
tset *_TypeSet // type set described by this interface, computed lazily
@@ -108,6 +109,9 @@
// set.
func (t *Interface) IsMethodSet() bool { return t.typeSet().IsMethodSet() }
+// IsImplicit reports whether the interface t is a wrapper for a type set literal.
+func (t *Interface) IsImplicit() bool { return t.implicit }
+
// 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
@@ -143,7 +147,6 @@
for _, f := range iface.Methods.List {
if len(f.Names) == 0 {
- // We have an embedded type; possibly a union of types.
addEmbedded(f.Type.Pos(), parseUnion(check, flattenUnion(nil, f.Type)))
continue
}
diff --git a/src/go/types/testdata/examples/typesets.go2 b/src/go/types/testdata/examples/typesets.go2
index 0a1b0f5..cf01072 100644
--- a/src/go/types/testdata/examples/typesets.go2
+++ b/src/go/types/testdata/examples/typesets.go2
@@ -46,3 +46,13 @@
// A type parameter may not be embedded in an interface;
// so it can also not be used as a constraint.
func _[A any, B A /* ERROR cannot use a type parameter as constraint */ ]() {}
+
+// Error messages refer to the type constraint as it appears in the source.
+// (No implicit interface should be exposed.)
+func _[T string](x T) T {
+ return x /* ERROR constrained by string */ * x
+}
+
+func _[T int|string](x T) T {
+ return x /* ERROR constrained by int|string */ * x
+}
diff --git a/src/go/types/typeparam.go b/src/go/types/typeparam.go
index 51bedc2..e2755cb 100644
--- a/src/go/types/typeparam.go
+++ b/src/go/types/typeparam.go
@@ -108,6 +108,7 @@
// TODO(gri) mark it as implicit - see comment in Checker.bound
if ityp == nil {
ityp = NewInterfaceType(nil, []Type{bound})
+ ityp.implicit = true
t.bound = ityp // update t.bound for next time (optimization)
}
diff --git a/src/go/types/typestring.go b/src/go/types/typestring.go
index 4a087c4..a0c78e8 100644
--- a/src/go/types/typestring.go
+++ b/src/go/types/typestring.go
@@ -191,6 +191,15 @@
}
case *Interface:
+ if t.implicit {
+ if len(t.methods) == 0 && len(t.embeddeds) == 1 {
+ w.typ(t.embeddeds[0])
+ break
+ }
+ // Something's wrong with the implicit interface.
+ // Print it as such and continue.
+ w.string("/* implicit */ ")
+ }
w.string("interface{")
first := true
for _, m := range t.methods {
diff --git a/src/go/types/universe.go b/src/go/types/universe.go
index 4d52242..519cf0b 100644
--- a/src/go/types/universe.go
+++ b/src/go/types/universe.go
@@ -89,7 +89,7 @@
res := NewVar(token.NoPos, nil, "", Typ[String])
sig := NewSignatureType(nil, nil, nil, nil, NewTuple(res), false)
err := NewFunc(token.NoPos, nil, "Error", sig)
- ityp := &Interface{nil, obj, []*Func{err}, nil, nil, true, nil}
+ ityp := &Interface{nil, obj, []*Func{err}, nil, nil, false, true, nil}
computeInterfaceTypeSet(nil, token.NoPos, ityp) // prevent races due to lazy computation of tset
typ := NewNamed(obj, ityp, nil)
sig.recv = NewVar(token.NoPos, nil, "", typ)
@@ -100,7 +100,7 @@
{
obj := NewTypeName(token.NoPos, nil, "comparable", nil)
obj.setColor(black)
- ityp := &Interface{nil, obj, nil, nil, nil, true, &_TypeSet{true, nil, allTermlist}}
+ ityp := &Interface{nil, obj, nil, nil, nil, false, true, &_TypeSet{true, nil, allTermlist}}
NewNamed(obj, ityp, nil)
def(obj)
}
