go/types, types2: document that exported predicates are unspecified for invalid type arguments
Per discussion on the issue.
For #53595.
Change-Id: Iefd161e5c7e792d454652cbe831a0c2d769f748e
Reviewed-on: https://go-review.googlesource.com/c/go/+/415574
Reviewed-by: Robert Findley <rfindley@google.com>
Reviewed-by: Robert Griesemer <gri@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
diff --git a/src/cmd/compile/internal/types2/api.go b/src/cmd/compile/internal/types2/api.go
index a22ea5d..94c290b 100644
--- a/src/cmd/compile/internal/types2/api.go
+++ b/src/cmd/compile/internal/types2/api.go
@@ -418,7 +418,8 @@
// AssertableTo reports whether a value of type V can be asserted to have type T.
//
-// The behavior of AssertableTo is undefined in two cases:
+// The behavior of AssertableTo is unspecified in three cases:
+// - if T is Typ[Invalid]
// - if V is a generalized interface; i.e., an interface that may only be used
// as a type constraint in Go code
// - if T is an uninstantiated generic type
@@ -434,8 +435,8 @@
// AssignableTo reports whether a value of type V is assignable to a variable
// of type T.
//
-// The behavior of AssignableTo is undefined if V or T is an uninstantiated
-// generic type.
+// The behavior of AssignableTo is unspecified if V or T is Typ[Invalid] or an
+// uninstantiated generic type.
func AssignableTo(V, T Type) bool {
x := operand{mode: value, typ: V}
ok, _ := x.assignableTo(nil, T, nil) // check not needed for non-constant x
@@ -445,8 +446,8 @@
// ConvertibleTo reports whether a value of type V is convertible to a value of
// type T.
//
-// The behavior of ConvertibleTo is undefined if V or T is an uninstantiated
-// generic type.
+// The behavior of ConvertibleTo is unspecified if V or T is Typ[Invalid] or an
+// uninstantiated generic type.
func ConvertibleTo(V, T Type) bool {
x := operand{mode: value, typ: V}
return x.convertibleTo(nil, T, nil) // check not needed for non-constant x
@@ -454,8 +455,8 @@
// Implements reports whether type V implements interface T.
//
-// The behavior of Implements is undefined if V is an uninstantiated generic
-// type.
+// The behavior of Implements is unspecified if V is Typ[Invalid] or an uninstantiated
+// generic type.
func Implements(V Type, T *Interface) bool {
if T.Empty() {
// All types (even Typ[Invalid]) implement the empty interface.
diff --git a/src/go/types/api.go b/src/go/types/api.go
index 0915d6a..5e7be29 100644
--- a/src/go/types/api.go
+++ b/src/go/types/api.go
@@ -413,7 +413,8 @@
// AssertableTo reports whether a value of type V can be asserted to have type T.
//
-// The behavior of AssertableTo is undefined in two cases:
+// The behavior of AssertableTo is unspecified in three cases:
+// - if T is Typ[Invalid]
// - if V is a generalized interface; i.e., an interface that may only be used
// as a type constraint in Go code
// - if T is an uninstantiated generic type
@@ -429,8 +430,8 @@
// AssignableTo reports whether a value of type V is assignable to a variable
// of type T.
//
-// The behavior of AssignableTo is undefined if V or T is an uninstantiated
-// generic type.
+// The behavior of AssignableTo is unspecified if V or T is Typ[Invalid] or an
+// uninstantiated generic type.
func AssignableTo(V, T Type) bool {
x := operand{mode: value, typ: V}
ok, _ := x.assignableTo(nil, T, nil) // check not needed for non-constant x
@@ -440,8 +441,8 @@
// ConvertibleTo reports whether a value of type V is convertible to a value of
// type T.
//
-// The behavior of ConvertibleTo is undefined if V or T is an uninstantiated
-// generic type.
+// The behavior of ConvertibleTo is unspecified if V or T is Typ[Invalid] or an
+// uninstantiated generic type.
func ConvertibleTo(V, T Type) bool {
x := operand{mode: value, typ: V}
return x.convertibleTo(nil, T, nil) // check not needed for non-constant x
@@ -449,8 +450,8 @@
// Implements reports whether type V implements interface T.
//
-// The behavior of Implements is undefined if V is an uninstantiated generic
-// type.
+// The behavior of Implements is unspecified if V is Typ[Invalid] or an uninstantiated
+// generic type.
func Implements(V Type, T *Interface) bool {
if T.Empty() {
// All types (even Typ[Invalid]) implement the empty interface.
