cmd/compile: fix stencil call expression.

Fixes: #47878
Change-Id: I369350813726fd518b4eab2b98f43bf031a6dee6
Reviewed-on: https://go-review.googlesource.com/c/go/+/344210
Reviewed-by: Dan Scales <danscales@google.com>
Trust: Dan Scales <danscales@google.com>
Trust: Keith Randall <khr@golang.org>
Run-TryBot: Dan Scales <danscales@google.com>
TryBot-Result: Go Bot <gobot@golang.org>

diff --git a/src/cmd/compile/internal/noder/stencil.go b/src/cmd/compile/internal/noder/stencil.go
index 18a05060369a38680154a71ec3b555067b4b7d38..b3ff4b8855c7b157b34ae38b1e26671201a93daa 100644 (file)
--- a/src/cmd/compile/internal/noder/stencil.go
+++ b/src/cmd/compile/internal/noder/stencil.go
@@ -1048,6 +1048,13 @@ func (subst *subster) node(n ir.Node) ir.Node {
                        case ir.OCLOSURE:
                                transformCall(call)
 
+                       case ir.ODEREF, ir.OINDEX, ir.OINDEXMAP, ir.ORECV:
+                               // Transform a call that was delayed because of the
+                               // use of typeparam inside an expression that required
+                               // a pointer dereference, array indexing, map indexing,
+                               // or channel receive to compute function value.
+                               transformCall(call)
+
                        case ir.OFUNCINST:
                                // A call with an OFUNCINST will get transformed
                                // in stencil() once we have created & attached the

diff --git a/test/typeparam/issue47878.go b/test/typeparam/issue47878.go
new file mode 100644 (file)
index 0000000..cb1043a
--- /dev/null
+++ b/test/typeparam/issue47878.go
@@ -0,0 +1,46 @@
+// 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 main
+
+type Src1[T any] func() Src1[T]
+
+func (s *Src1[T]) Next() {
+       *s = (*s)()
+}
+
+type Src2[T any] []func() Src2[T]
+
+func (s Src2[T]) Next() {
+       _ = s[0]()
+}
+
+type Src3[T comparable] map[T]func() Src3[T]
+
+func (s Src3[T]) Next() {
+       var a T
+       _ = s[a]()
+}
+
+type Src4[T any] chan func() T
+
+func (s Src4[T]) Next() {
+       _ = (<-s)()
+}
+
+func main() {
+       var src1 Src1[int]
+       src1.Next()
+
+       var src2 Src2[int]
+       src2.Next()
+
+       var src3 Src3[string]
+       src3.Next()
+
+       var src4 Src4[int]
+       src4.Next()
+}