[dev.typeparams] go/types: implement ch <- x where ch is of type parameter type

This is a port of CL 333712 to go/types, adjusted for the different
error reporting API and to position errors on the arrows.

Fixes #43671

Change-Id: I7d2de249e86d272c89a046f60e632e75848ff865
Reviewed-on: https://go-review.googlesource.com/c/go/+/335076
Trust: Robert Findley <rfindley@google.com>
Run-TryBot: Robert Findley <rfindley@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>

diff --git a/src/go/types/stmt.go b/src/go/types/stmt.go
index 53fccb0a6402389c8c8933514880f805fe2015db..0f0a2e4d9fd754a15049d569562c6da66f3d0d92 100644 (file)
--- a/src/go/types/stmt.go
+++ b/src/go/types/stmt.go
@@ -361,25 +361,33 @@ func (check *Checker) stmt(ctxt stmtContext, s ast.Stmt) {
                check.errorf(&x, code, "%s %s", &x, msg)
 
        case *ast.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.invalidOp(inNode(s, s.Arrow), _InvalidSend, "cannot send to non-chan type %s", ch.typ)
-                       return
-               }
-
-               if tch.dir == RecvOnly {
-                       check.invalidOp(inNode(s, s.Arrow), _InvalidSend, "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.invalidOp(inNode(s, s.Arrow), _InvalidSend, "cannot send to non-channel %s", &ch)
+                               return false
+                       }
+                       if uch.dir == RecvOnly {
+                               check.invalidOp(inNode(s, s.Arrow), _InvalidSend, "cannot send to receive-only channel %s", &ch)
+                               return false
+                       }
+                       if elem != nil && !Identical(uch.elem, elem) {
+                               check.invalidOp(inNode(s, s.Arrow), _Todo, "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 *ast.IncDecStmt:
                var op token.Token

diff --git a/src/go/types/testdata/fixedbugs/issue47115.go2 b/src/go/types/testdata/fixedbugs/issue47115.go2
new file mode 100644 (file)
index 0000000..6694219
--- /dev/null
+++ b/src/go/types/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
+}