[dev.typeparams] cmd/compile/internal/types2: implement ch <- x where ch is of type...

For #47115.

Change-Id: Ib9c8652c0346029369735ccf7ee9098ab1ae7fd3
Reviewed-on: https://go-review.googlesource.com/c/go/+/333712
Trust: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>

diff --git a/src/cmd/compile/internal/types2/stmt.go b/src/cmd/compile/internal/types2/stmt.go
index b41b23fedbcf1f6bd34ed46ee784cd5efcd0fcf9..9b8295c4f4d617f8bfc322b23a109ea6f56ca95c 100644 (file)
--- a/src/cmd/compile/internal/types2/stmt.go
+++ b/src/cmd/compile/internal/types2/stmt.go
@@ -352,25 +352,33 @@ func (check *Checker) stmt(ctxt stmtContext, s syntax.Stmt) {
                check.errorf(&x, "%s %s", &x, msg)
 
        case *syntax.SendStmt:
-               var ch, x operand
+               var ch, val operand
                check.expr(&ch, s.Chan)
-               check.expr(&x, s.Value)
-               if ch.mode == invalid || x.mode == invalid {
+               check.expr(&val, s.Value)
+               if ch.mode == invalid || val.mode == invalid {
                        return
                }
-
-               tch := asChan(ch.typ)
-               if tch == nil {
-                       check.errorf(s, invalidOp+"cannot send to non-chan type %s", ch.typ)
-                       return
-               }
-
-               if tch.dir == RecvOnly {
-                       check.errorf(s, invalidOp+"cannot send to receive-only type %s", tch)
+               var elem Type
+               if !underIs(ch.typ, func(u Type) bool {
+                       uch, _ := u.(*Chan)
+                       if uch == nil {
+                               check.errorf(s, invalidOp+"cannot send to non-channel %s", &ch)
+                               return false
+                       }
+                       if uch.dir == RecvOnly {
+                               check.errorf(s, invalidOp+"cannot send to receive-only channel %s", &ch)
+                               return false
+                       }
+                       if elem != nil && !Identical(uch.elem, elem) {
+                               check.errorf(s, invalidOp+"channels of %s must have the same element type", &ch)
+                               return false
+                       }
+                       elem = uch.elem
+                       return true
+               }) {
                        return
                }
-
-               check.assignment(&x, tch.elem, "send")
+               check.assignment(&val, elem, "send")
 
        case *syntax.AssignStmt:
                lhs := unpackExpr(s.Lhs)

diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue47115.go2 b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue47115.go2
new file mode 100644 (file)
index 0000000..00828eb
--- /dev/null
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue47115.go2
@@ -0,0 +1,40 @@
+// 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 C0 interface{ int }
+type C1 interface{ chan int }
+type C2 interface{ chan int | <-chan int }
+type C3 interface{ chan int | chan float32 }
+type C4 interface{ chan int | chan<- int }
+type C5[T any] interface{ ~chan T | chan<- T }
+
+func _[T any](ch T) {
+       ch /* ERROR cannot send to non-channel */ <- 0
+}
+
+func _[T C0](ch T) {
+       ch /* ERROR cannot send to non-channel */ <- 0
+}
+
+func _[T C1](ch T) {
+       ch <- 0
+}
+
+func _[T C2](ch T) {
+       ch /* ERROR cannot send to receive-only channel */ <- 0
+}
+
+func _[T C3](ch T) {
+       ch /* ERROR channels of ch .* must have the same element type */ <- 0
+}
+
+func _[T C4](ch T) {
+       ch <- 0
+}
+
+func _[T C5[X], X any](ch T, x X) {
+       ch <- x
+}