Go patch committed: Don't permit close of receive-only channel

[Ian Lance Taylor]

The Go language was changed slightly to prohibit calling close on a
receive-only channel.  This patch changes the Go frontend accordingly.
This patch also implements a better panic for an attempt to close a nil
channel.  Bootstrapped and ran Go testsuite on x86_64-unknown-linux-gnu.
Committed to mainline.

Ian


diff -r 4dea0e134ef6 go/expressions.cc
--- a/go/expressions.cc	Mon Oct 24 22:36:05 2011 -0700
+++ b/go/expressions.cc	Tue Oct 25 09:07:49 2011 -0700
@@ -8153,6 +8153,8 @@
 	{
 	  if (this->one_arg()->type()->channel_type() == NULL)
 	    this->report_error(_("argument must be channel"));
+	  else if (!this->one_arg()->type()->channel_type()->may_send())
+	    this->report_error(_("cannot close receive-only channel"));
 	}
       break;
 
diff -r 4dea0e134ef6 libgo/runtime/go-close.c
--- a/libgo/runtime/go-close.c	Mon Oct 24 22:36:05 2011 -0700
+++ b/libgo/runtime/go-close.c	Tue Oct 25 09:07:49 2011 -0700
@@ -16,6 +16,9 @@
 {
   int i;
 
+  if (channel == NULL)
+    __go_panic_msg ("close of nil channel");
+
   i = pthread_mutex_lock (&channel->lock);
   __go_assert (i == 0);