cmd/compile/internal/types2: use correct types when checking generic conversions
Iterate through the actual, possibly defined types of constraints
when type-checking generic conversions, not the underlying types.
For #47150.
Change-Id: Ia7af313bf46d6f6b0ad5292ff793b030b8e2d3d8
Reviewed-on: https://go-review.googlesource.com/c/go/+/357333
Trust: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Griesemer <gri@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>
diff --git a/src/cmd/compile/internal/types2/conversions.go b/src/cmd/compile/internal/types2/conversions.go
index 8cd74b8..112d728 100644
--- a/src/cmd/compile/internal/types2/conversions.go
+++ b/src/cmd/compile/internal/types2/conversions.go
@@ -98,21 +98,21 @@
switch {
case Vp != nil && Tp != nil:
x := *x // don't modify outer x
- return Vp.underIs(func(V Type) bool {
- x.typ = V
- return Tp.underIs(func(T Type) bool {
- return x.convertibleToImpl(check, T)
+ return Vp.is(func(V *term) bool {
+ x.typ = V.typ
+ return Tp.is(func(T *term) bool {
+ return x.convertibleToImpl(check, T.typ)
})
})
case Vp != nil:
x := *x // don't modify outer x
- return Vp.underIs(func(V Type) bool {
- x.typ = V
+ return Vp.is(func(V *term) bool {
+ x.typ = V.typ
return x.convertibleToImpl(check, T)
})
case Tp != nil:
- return Tp.underIs(func(T Type) bool {
- return x.convertibleToImpl(check, T)
+ return Tp.is(func(T *term) bool {
+ return x.convertibleToImpl(check, T.typ)
})
}
diff --git a/src/cmd/compile/internal/types2/testdata/examples/conversions.go2 b/src/cmd/compile/internal/types2/testdata/examples/conversions.go2
index 7e9e974..5c1b30a 100644
--- a/src/cmd/compile/internal/types2/testdata/examples/conversions.go2
+++ b/src/cmd/compile/internal/types2/testdata/examples/conversions.go2
@@ -31,6 +31,20 @@
func _[X ~*Foo, T ~*Foo|~*Bar](x X) T { return T(x) }
func _[X ~*Foo, T ~*Far](x X) T { return T(x /* ERROR cannot convert */ ) }
+// Verify that the defined types in constraints are considered for the rule above.
+
+type (
+ B int
+ C int
+ X0 *B
+ T0 *C
+)
+
+func _(x X0) T0 { return T0(x /* ERROR cannot convert */ ) } // non-generic reference
+func _[X X0, T T0](x X) T { return T(x /* ERROR cannot convert */ ) }
+func _[T T0](x X0) T { return T(x /* ERROR cannot convert */ ) }
+func _[X X0](x X) T0 { return T0(x /* ERROR cannot convert */ ) }
+
// "x's type and T are both integer or floating point types"
func _[X Integer, T Integer](x X) T { return T(x) }
