From 975a114c0f847a0b12a0384d0f804ca46f900281 Mon Sep 17 00:00:00 2001
From: Derek Parker <derek.parker@coreos.com>
Date: Sun, 31 Jan 2016 11:14:58 +0100
Subject: [PATCH] trace: Fix panic calling trace without arg

---
 cmd/dlv/main.go | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/cmd/dlv/main.go b/cmd/dlv/main.go
index e6967b64..da245f0b 100644
--- a/cmd/dlv/main.go
+++ b/cmd/dlv/main.go
@@ -144,6 +144,10 @@ starts and attaches to it, and enables you to immediately begin debugging your p
 		Long:  "Trace program execution. Will set a tracepoint on every function matching [regexp] and output information when tracepoint is hit.",
 		Run: func(cmd *cobra.Command, args []string) {
 			status := func() int {
+				if len(args) == 0 {
+					fmt.Fprintln(os.Stderr, "You must provide a function to trace.")
+					return 1
+				}
 				const debugname = "debug"
 				var processArgs []string
 				if traceAttachPid == 0 {