[dev.typeparams] cmd/compile/internal/types2: don't permit method calls on ptr to type parameter receivers
Simplify the implementation of asInterface while at it.
For #47031.
Change-Id: Ie7d4fbbab898d961ed3c0b7772ba9604641be13f
Reviewed-on: https://go-review.googlesource.com/c/go/+/332609
Trust: Robert Griesemer <gri@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>
diff --git a/src/cmd/compile/internal/types2/lookup.go b/src/cmd/compile/internal/types2/lookup.go
index d59a2f4..91be14b 100644
--- a/src/cmd/compile/internal/types2/lookup.go
+++ b/src/cmd/compile/internal/types2/lookup.go
@@ -73,10 +73,12 @@
typ, isPtr := deref(T)
- // *typ where typ is an interface has no methods.
- // Be cautious: typ may be nil (issue 39634, crash #3).
- if typ == nil || isPtr && IsInterface(typ) {
- return
+ // *typ where typ is an interface or type parameter has no methods.
+ switch under(typ).(type) {
+ case *Interface, *TypeParam:
+ if isPtr {
+ return
+ }
}
// Start with typ as single entry at shallowest depth.
diff --git a/src/cmd/compile/internal/types2/testdata/check/issues.go2 b/src/cmd/compile/internal/types2/testdata/check/issues.go2
index 59dd4ae..88ae294 100644
--- a/src/cmd/compile/internal/types2/testdata/check/issues.go2
+++ b/src/cmd/compile/internal/types2/testdata/check/issues.go2
@@ -24,22 +24,20 @@
eql[io.Reader](nil, nil)
}
-// If we have a receiver of pointer type (below: *T) we must ignore
-// the pointer in the implementation of the method lookup because
-// the type bound of T is an interface and pointer to interface types
-// have no methods and then the lookup would fail.
+// If we have a receiver of pointer to type parameter type (below: *T)
+// we don't have any methods, like for interfaces.
type C[T any] interface {
m()
}
// using type bound C
func _[T C[T]](x *T) {
- x.m()
+ x.m /* ERROR x\.m undefined */ ()
}
// using an interface literal as bound
func _[T interface{ m() }](x *T) {
- x.m()
+ x.m /* ERROR x\.m undefined */ ()
}
func f2[_ interface{ m1(); m2() }]()
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue47031.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue47031.go2
new file mode 100644
index 0000000..b184f9b
--- /dev/null
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue47031.go2
@@ -0,0 +1,20 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+type Mer interface { M() }
+
+func F[T Mer](p *T) {
+ p.M /* ERROR p\.M undefined */ ()
+}
+
+type MyMer int
+
+func (MyMer) M() {}
+
+func _() {
+ F(new(MyMer))
+ F[Mer](nil)
+}
diff --git a/src/cmd/compile/internal/types2/type.go b/src/cmd/compile/internal/types2/type.go
index e3f63f6..c2da976 100644
--- a/src/cmd/compile/internal/types2/type.go
+++ b/src/cmd/compile/internal/types2/type.go
@@ -112,11 +112,6 @@
return op
}
-func asInterface(t Type) *Interface {
- op, _ := optype(t).(*Interface)
- return op
-}
-
func asMap(t Type) *Map {
op, _ := optype(t).(*Map)
return op
@@ -127,10 +122,16 @@
return op
}
-// If the argument to asNamed and asTypeParam is of the respective types
+// If the argument to asInterface, asNamed, or asTypeParam is of the respective type
// (possibly after expanding an instance type), these methods return that type.
// Otherwise the result is nil.
+// asInterface does not need to look at optype (type sets don't contain interfaces)
+func asInterface(t Type) *Interface {
+ u, _ := under(t).(*Interface)
+ return u
+}
+
func asNamed(t Type) *Named {
e, _ := expand(t).(*Named)
return e
