From: David Symonds <dsymonds@golang.org>
Date: Wed, 19 Sep 2012 22:12:47 +0000 (+1000)
Subject: vet: fix rangeloop.
X-Git-Tag: go1.1rc2~2397
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=5a93fea08e7c9cbc4ed5ab7ba161b3e078497fb3;p=gostls13.git

vet: fix rangeloop.

In a range loop, the presence of a value implies the presence of a key.
However, the presence of a value as an *ast.Ident does not imply that
the key is also an *ast.Ident, thus leading to a panic any time the
two argument form is used where the key is not an identifier.

R=golang-dev, adg, r
CC=golang-dev
https://golang.org/cl/6540045
---

diff --git a/src/cmd/vet/rangeloop.go b/src/cmd/vet/rangeloop.go
index 2fdb0b6216..71cbc11579 100644
--- a/src/cmd/vet/rangeloop.go
+++ b/src/cmd/vet/rangeloop.go
@@ -53,8 +53,12 @@ func checkRangeLoop(f *File, n *ast.RangeStmt) {
 		return
 	}
 	ast.Inspect(lit.Body, func(n ast.Node) bool {
-		if n, ok := n.(*ast.Ident); ok && n.Obj != nil && (n.Obj == key.Obj || n.Obj == val.Obj) {
-			f.Warn(n.Pos(), "range variable", n.Name, "enclosed by function")
+		id, ok := n.(*ast.Ident)
+		if !ok || id.Obj == nil {
+			return true
+		}
+		if key != nil && id.Obj == key.Obj || val != nil && id.Obj == val.Obj {
+			f.Warn(id.Pos(), "range variable", id.Name, "enclosed by function")
 		}
 		return true
 	})
@@ -101,4 +105,13 @@ func BadRangeLoopsUsedInTests() {
 			println(i, v)
 		}()
 	}
+	// If the key of the range statement is not an identifier
+	// the code should not panic (it used to).
+	var x [2]int
+	var f int
+	for x[0], f = range s {
+		go func() {
+			_ = f // ERROR "range variable f enclosed by function"
+		}()
+	}
 }