From 73612ddbfdaa5cabf51a2d2b77db6f158d17802a Mon Sep 17 00:00:00 2001
From: Rob Pike <r@golang.org>
Date: Mon, 10 Jun 2013 15:58:32 -0700
Subject: [PATCH] go.tools/cmd/cover: handle empty select Putting a coverage
 counter inside select{} is invalid Go.

R=adonovan
CC=golang-dev
https://golang.org/cl/10175043
---
 cmd/cover/cover.go | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/cmd/cover/cover.go b/cmd/cover/cover.go
index d6ce70a87c..d13ac54a1e 100644
--- a/cmd/cover/cover.go
+++ b/cmd/cover/cover.go
@@ -107,6 +107,16 @@ func (f *File) Visit(node ast.Node) ast.Visitor {
 			}
 		}
 		n.List = f.addCounters(n.Pos(), n.End(), n.List)
+	case *ast.SelectStmt:
+		// Don't annotate an empty select - creates a syntax error.
+		if n.Body == nil || len(n.Body.List) == 0 {
+			return nil
+		}
+	case *ast.SwitchStmt:
+		// Don't annotate an empty switch - creates a syntax error.
+		if n.Body == nil || len(n.Body.List) == 0 {
+			return nil
+		}
 	}
 	return f
 }