From e078800d1f47ca3cf12d68aaee1eb05147c672b3 Mon Sep 17 00:00:00 2001
From: Robert Griesemer <gri@golang.org>
Date: Tue, 15 Jul 2014 08:54:09 -0700
Subject: [PATCH] go/types: permit "for range x"

LGTM=adonovan
R=adonovan
CC=golang-codereviews
https://golang.org/cl/110630044
---
 go/types/stmt.go            |  6 +-----
 go/types/testdata/stmt0.src | 10 ++++++++++
 2 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/go/types/stmt.go b/go/types/stmt.go
index e7581f88..fe3c0d64 100644
--- a/go/types/stmt.go
+++ b/go/types/stmt.go
@@ -656,10 +656,6 @@ func (check *Checker) stmt(ctxt stmtContext, s ast.Stmt) {
 
 		// check assignment to/declaration of iteration variables
 		// (irregular assignment, cannot easily map to existing assignment checks)
-		if s.Key == nil {
-			check.invalidAST(s.Pos(), "range clause requires index iteration variable")
-			// ok to continue
-		}
 
 		// lhs expressions and initialization value (rhs) types
 		lhs := [2]ast.Expr{s.Key, s.Value}
@@ -701,7 +697,7 @@ func (check *Checker) stmt(ctxt stmtContext, s ast.Stmt) {
 			// declare variables
 			if len(vars) > 0 {
 				for _, obj := range vars {
-					check.declare(check.scope, nil, obj) // recordObject already called
+					check.declare(check.scope, nil /* recordDef already called */, obj)
 				}
 			} else {
 				check.error(s.TokPos, "no new variables on left side of :=")
diff --git a/go/types/testdata/stmt0.src b/go/types/testdata/stmt0.src
index 6cf22141..9a98a1e1 100644
--- a/go/types/testdata/stmt0.src
+++ b/go/types/testdata/stmt0.src
@@ -631,9 +631,11 @@ func rangeloops1() {
 		rc <-chan int
 	)
 
+	for range x /* ERROR "cannot range over" */ {}
 	for _ = range x /* ERROR "cannot range over" */ {}
 	for i := range x /* ERROR "cannot range over" */ {}
 
+	for range a {}
 	for i := range a {
 		var ii int
 		ii = i
@@ -652,6 +654,7 @@ func rangeloops1() {
 	for ii, xx = range a {}
 	_, _ = ii, xx
 
+	for range b {}
 	for i := range b {
 		var ii int
 		ii = i
@@ -666,6 +669,7 @@ func rangeloops1() {
 		_ = xx
 	}
 
+	for range s {}
 	for i := range s {
 		var ii int
 		ii = i
@@ -680,14 +684,17 @@ func rangeloops1() {
 		_ = xx
 	}
 
+	for range p {}
 	for _, x := range p {
 		var xx complex128
 		xx = x
 		_ = xx
 	}
 
+	for range pp /* ERROR "cannot range over" */ {}
 	for _, x := range pp /* ERROR "cannot range over" */ {}
 
+	for range m {}
 	for k := range m {
 		var kk int32
 		kk = k /* ERROR "cannot assign" */
@@ -700,6 +707,7 @@ func rangeloops1() {
 		if v {}
 	}
 
+	for range c {}
 	for _, _ /* ERROR "only one iteration variable" */ = range c {}
 	for e := range c {
 		var ee int
@@ -711,6 +719,8 @@ func rangeloops1() {
 
 	// constant strings
 	const cs = "foo"
+	for range cs {}
+	for range "" {}
 	for i, x := range cs { _, _ = i, x }
 	for i, x := range "" {
 		var ii int