cmd/gc: support x[i:j:k]

Design doc at golang.org/s/go12slice.
This is an experimental feature and may not be included in the release.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/10743046

1 files changed, 121 insertions, 0 deletions

diff --git a/test/slice3err.go b/test/slice3err.go
new file mode 100644
index 0000000000..c48ebfeaee
--- /dev/null
+++ b/test/slice3err.go
@@ -0,0 +1,121 @@
+// errorcheck
+
+// Copyright 2013 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+var array *[10]int
+var slice []int
+var str string
+var i, j, k int
+
+func f() {
+	// check what missing arguments are allowed
+	_ = array[:]
+	_ = array[i:]
+	_ = array[:j]
+	_ = array[i:j]
+	_ = array[::] // ERROR "middle index required in 3-index slice" "final index required in 3-index slice"
+	_ = array[i::] // ERROR "middle index required in 3-index slice" "final index required in 3-index slice"
+	_ = array[:j:] // ERROR "final index required in 3-index slice"
+	_ = array[i:j:] // ERROR  "final index required in 3-index slice"
+	_ = array[::k] // ERROR "middle index required in 3-index slice"
+	_ = array[i::k] // ERROR "middle index required in 3-index slice"
+	_ = array[:j:k]
+	_ = array[i:j:k]
+	
+	_ = slice[:]
+	_ = slice[i:]
+	_ = slice[:j]
+	_ = slice[i:j]
+	_ = slice[::] // ERROR "middle index required in 3-index slice" "final index required in 3-index slice"
+	_ = slice[i::] // ERROR "middle index required in 3-index slice" "final index required in 3-index slice"
+	_ = slice[:j:] // ERROR "final index required in 3-index slice"
+	_ = slice[i:j:] // ERROR "final index required in 3-index slice"
+	_ = slice[::k] // ERROR "middle index required in 3-index slice"
+	_ = slice[i::k] // ERROR "middle index required in 3-index slice"
+	_ = slice[:j:k]
+	_ = slice[i:j:k]
+	
+	_ = str[:]
+	_ = str[i:]
+	_ = str[:j]
+	_ = str[i:j]
+	_ = str[::] // ERROR "3-index slice of string" "middle index required in 3-index slice" "final index required in 3-index slice"
+	_ = str[i::] // ERROR "3-index slice of string" "middle index required in 3-index slice" "final index required in 3-index slice"
+	_ = str[:j:] // ERROR "3-index slice of string" "final index required in 3-index slice"
+	_ = str[i:j:] // ERROR "3-index slice of string" "final index required in 3-index slice"
+	_ = str[::k] // ERROR "3-index slice of string" "middle index required in 3-index slice"
+	_ = str[i::k] // ERROR "3-index slice of string" "middle index required in 3-index slice"
+	_ = str[:j:k] // ERROR "3-index slice of string"
+	_ = str[i:j:k] // ERROR "3-index slice of string"
+
+	// check invalid indices
+	_ = array[1:2]
+	_ = array[2:1] // ERROR "invalid slice index"
+	_ = array[2:2]
+	_ = array[i:1]
+	_ = array[1:j]
+	_ = array[1:2:3]
+	_ = array[1:3:2] // ERROR "invalid slice index"
+	_ = array[2:1:3] // ERROR "invalid slice index"
+	_ = array[2:3:1] // ERROR "invalid slice index"
+	_ = array[3:1:2] // ERROR "invalid slice index"
+	_ = array[3:2:1] // ERROR "invalid slice index"
+	_ = array[i:1:2]
+	_ = array[i:2:1] // ERROR "invalid slice index"
+	_ = array[1:j:2]
+	_ = array[2:j:1] // ERROR "invalid slice index"
+	_ = array[1:2:k]
+	_ = array[2:1:k] // ERROR "invalid slice index"
+	
+	_ = slice[1:2]
+	_ = slice[2:1] // ERROR "invalid slice index"
+	_ = slice[2:2]
+	_ = slice[i:1]
+	_ = slice[1:j]
+	_ = slice[1:2:3]
+	_ = slice[1:3:2] // ERROR "invalid slice index"
+	_ = slice[2:1:3] // ERROR "invalid slice index"
+	_ = slice[2:3:1] // ERROR "invalid slice index"
+	_ = slice[3:1:2] // ERROR "invalid slice index"
+	_ = slice[3:2:1] // ERROR "invalid slice index"
+	_ = slice[i:1:2]
+	_ = slice[i:2:1] // ERROR "invalid slice index"
+	_ = slice[1:j:2]
+	_ = slice[2:j:1] // ERROR "invalid slice index"
+	_ = slice[1:2:k]
+	_ = slice[2:1:k] // ERROR "invalid slice index"
+	
+	_ = str[1:2]
+	_ = str[2:1] // ERROR "invalid slice index"
+	_ = str[2:2]
+	_ = str[i:1]
+	_ = str[1:j]
+
+	// check out of bounds indices on array
+	_ = array[11:11] // ERROR "out of bounds for 10-element array"
+	_ = array[11:12] // ERROR "out of bounds for 10-element array"
+	_ = array[11:] // ERROR "out of bounds for 10-element array"
+	_ = array[:11] // ERROR "out of bounds for 10-element array"
+	_ = array[1:11] // ERROR "out of bounds for 10-element array"
+	_ = array[1:11:12] // ERROR "out of bounds for 10-element array"
+	_ = array[1:2:11] // ERROR "out of bounds for 10-element array"
+	_ = array[1:11:3] // ERROR "out of bounds for 10-element array"
+	_ = array[11:2:3] // ERROR "out of bounds for 10-element array"
+	_ = array[11:12:13] // ERROR "out of bounds for 10-element array"
+
+	// slice bounds not checked
+	_ = slice[11:11]
+	_ = slice[11:12]
+	_ = slice[11:]
+	_ = slice[:11]
+	_ = slice[1:11]
+	_ = slice[1:11:12]
+	_ = slice[1:2:11]
+	_ = slice[1:11:3] // ERROR "invalid slice index"
+	_ = slice[11:2:3] // ERROR "invalid slice index"
+	_ = slice[11:12:13]
+}