From a42e8a80864281807384a6e5a45bebf3327a53fe Mon Sep 17 00:00:00 2001
From: Robert Griesemer <gri@golang.org>
Date: Fri, 16 Nov 2012 11:53:26 -0800
Subject: [PATCH] go/ast: FuncType.Params may be nil (per AST documentation)

ast.Walk needs to check for it or it will crash.

R=r
CC=golang-dev
https://golang.org/cl/6852062
---
 src/pkg/go/ast/walk.go | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/pkg/go/ast/walk.go b/src/pkg/go/ast/walk.go
index 66b1dc2499..fef2503c37 100644
--- a/src/pkg/go/ast/walk.go
+++ b/src/pkg/go/ast/walk.go
@@ -158,7 +158,9 @@ func Walk(v Visitor, node Node) {
 		Walk(v, n.Fields)
 
 	case *FuncType:
-		Walk(v, n.Params)
+		if n.Params != nil {
+			Walk(v, n.Params)
+		}
 		if n.Results != nil {
 			Walk(v, n.Results)
 		}
-- 
2.48.1