1 files changed, 85 insertions, 0 deletions
diff --git a/test/fixedbugs/issue6847.go b/test/fixedbugs/issue6847.go
new file mode 100644
index 000000000..e6427e19a
--- /dev/null
+++ b/test/fixedbugs/issue6847.go
@@ -0,0 +1,85 @@
+// compile
+
+// Copyright 2014 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.
+
+// Issue 6847: select clauses involving implicit conversion
+// of channels trigger a spurious typechecking error during walk.
+
+package p
+
+type I1 interface {
+	String()
+}
+type I2 interface {
+	String()
+}
+
+func F() {
+	var (
+		cr <-chan int
+		cs chan<- int
+		c  chan int
+
+		ccr chan (<-chan int)
+		ccs chan chan<- int
+		cc  chan chan int
+
+		ok bool
+	)
+	// Send cases.
+	select {
+	case ccr <- cr:
+	case ccr <- c:
+	}
+	select {
+	case ccs <- cs:
+	case ccs <- c:
+	}
+	select {
+	case ccr <- c:
+	default:
+	}
+	// Receive cases.
+	select {
+	case cr = <-cc:
+	case cs = <-cc:
+	case c = <-cc:
+	}
+	select {
+	case cr = <-cc:
+	default:
+	}
+	select {
+	case cr, ok = <-cc:
+	case cs, ok = <-cc:
+	case c = <-cc:
+	}
+      // Interfaces.
+	var (
+		c1 chan I1
+		c2 chan I2
+		x1 I1
+		x2 I2
+	)
+	select {
+	case c1 <- x1:
+	case c1 <- x2:
+	case c2 <- x1:
+	case c2 <- x2:
+	}
+	select {
+	case x1 = <-c1:
+	case x1 = <-c2:
+	case x2 = <-c1:
+	case x2 = <-c2:
+	}
+	select {
+	case x1, ok = <-c1:
+	case x1, ok = <-c2:
+	case x2, ok = <-c1:
+	case x2, ok = <-c2:
+	}
+	_ = ok
+}