cmd/compile: fix wrong instantiated type for embedded receiver

In case of embedded field, if the receiver was fully instantiated, we
must use its instantiated type, instead of passing the type params of
the base receiver.

Fixes #47797
Fixes #48253

Change-Id: I97613e7e669a72605137e82406f7bf5fbb629378
Reviewed-on: https://go-review.googlesource.com/c/go/+/348549
Trust: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Trust: Dan Scales <danscales@google.com>
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Dan Scales <danscales@google.com>

diff --git a/src/cmd/compile/internal/noder/expr.go b/src/cmd/compile/internal/noder/expr.go
index 5eeafddae2ace2f84e877c3331e62c6b6defa41e..045f028e1aa124c3dddb46a0e7a7e89ede6fb822 100644 (file)
--- a/src/cmd/compile/internal/noder/expr.go
+++ b/src/cmd/compile/internal/noder/expr.go
@@ -360,12 +360,10 @@ func (g *irgen) selectorExpr(pos src.XPos, typ types2.Type, expr *syntax.Selecto
                                n.(*ir.SelectorExpr).Selection.Nname = method
                                typed(method.Type(), n)
 
-                               // selinfo.Targs() are the types used to
-                               // instantiate the type of receiver
-                               targs2 := getTargs(selinfo)
-                               targs := make([]ir.Node, targs2.Len())
+                               xt := deref(x.Type())
+                               targs := make([]ir.Node, len(xt.RParams()))
                                for i := range targs {
-                                       targs[i] = ir.TypeNode(g.typ(targs2.At(i)))
+                                       targs[i] = ir.TypeNode(xt.RParams()[i])
                                }
 
                                // Create function instantiation with the type
@@ -388,16 +386,6 @@ func (g *irgen) selectorExpr(pos src.XPos, typ types2.Type, expr *syntax.Selecto
        return n
 }
 
-// getTargs gets the targs associated with the receiver of a selected method
-func getTargs(selinfo *types2.Selection) *types2.TypeList {
-       r := deref2(selinfo.Recv())
-       n := types2.AsNamed(r)
-       if n == nil {
-               base.Fatalf("Incorrect type for selinfo %v", selinfo)
-       }
-       return n.TypeArgs()
-}
-
 func (g *irgen) exprList(expr syntax.Expr) []ir.Node {
        return g.exprs(unpackListExpr(expr))
 }

diff --git a/test/typeparam/issue47797.go b/test/typeparam/issue47797.go
new file mode 100644 (file)
index 0000000..3e80d3c
--- /dev/null
+++ b/test/typeparam/issue47797.go
@@ -0,0 +1,22 @@
+// compile -G=3
+
+// 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 Foo[T any] struct {
+        Val T
+}
+
+func (f Foo[T]) Bat() {}
+
+type Bar struct {
+        Foo[int]
+}
+
+func foo() {
+        var b Bar
+        b.Bat()
+}

diff --git a/test/typeparam/issue48253.go b/test/typeparam/issue48253.go
new file mode 100644 (file)
index 0000000..7bd0234
--- /dev/null
+++ b/test/typeparam/issue48253.go
@@ -0,0 +1,34 @@
+// run -gcflags="-G=3"
+
+// 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 main
+
+import (
+       "reflect"
+)
+
+type A[T any] struct {
+       B[int]
+}
+
+type B[T any] struct {
+}
+
+func (b B[T]) Bat() {
+       t := new(T)
+       if tt := reflect.TypeOf(t); tt.Kind() != reflect.Pointer || tt.Elem().Kind() != reflect.Int {
+               panic("unexpected type, want: *int, got: "+tt.String())
+       }
+}
+
+type Foo struct {
+       A[string]
+}
+func main() {
+       Foo{}.A.Bat()
+       Foo{}.A.B.Bat()
+       Foo{}.Bat()
+}