test: test cases for issue 1708.

R=rsc
CC=golang-dev
https://golang.org/cl/4548058

test/golden.out

@@ -40,6 +40,21 @@ hello, world
 -9223372036854775808
 9223372036854775807
 
+=========== ./shift1.go
+BUG: errchk: ./shift1.go:33: error message does not match 'overflow'
+errchk: ./shift1.go:34: error message does not match 'overflow'
+errchk: ./shift1.go:35: error message does not match 'overflow'
+
+=========== ./shift2.go
+./shift2.go:22: illegal constant expression: ideal LSH uint
+./shift2.go:35: illegal constant expression: ideal LSH uint
+./shift2.go:36: illegal constant expression: ideal LSH uint
+./shift2.go:36: invalid operation: 2 << c (shift of type float64)
+./shift2.go:39: illegal constant expression: ideal LSH uint
+./shift2.go:40: illegal constant expression: ideal LSH uint
+./shift2.go:40: invalid operation: 2 << c (shift of type float64)
+./shift2.go:40: cannot use 2 << c as type interface { } in function argument
+
 =========== ./sigchld.go
 survived SIGCHLD
 

test/shift1.go

@@ -0,0 +1,36 @@
+// errchk $G -e $D/$F.go
+
+// Copyright 2011 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.
+
+// Issue 1708, illegal cases.
+
+package p
+
+func f(x int) int         { return 0 }
+func g(x interface{}) int { return 0 }
+func h(x float64) int     { return 0 }
+
+// from the spec
+var (
+	s uint    = 33
+	u         = 1.0 << s // ERROR "invalid operation"
+	v float32 = 1 << s   // ERROR "invalid operation"
+)
+
+// non-constant shift expressions
+var (
+	e1       = g(2.0 << s) // ERROR "invalid operation"
+	f1       = h(2 << s)   // ERROR "invalid operation"
+	g1 int64 = 1.1 << s    // ERROR "truncated"
+)
+
+// constant shift expressions
+const c uint = 65
+
+var (
+	a2 int = 1.0 << c    // ERROR "overflow"
+	b2     = 1.0 << c    // ERROR "overflow"
+	d2     = f(1.0 << c) // ERROR "overflow"
+)

test/shift2.go

@@ -0,0 +1,42 @@
+// $G $D/$F.go && $L $F.$A && ./$A.out
+
+// Copyright 2011 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.
+
+// Issue 1708, legal cases.
+
+package p
+
+func f(x int) int         { return 0 }
+func g(x interface{}) int { return 0 }
+func h(x float64) int     { return 0 }
+
+// from the spec
+var (
+	s uint  = 33
+	i       = 1 << s         // 1 has type int
+	j int32 = 1 << s         // 1 has type int32; j == 0
+	k       = uint64(1 << s) // 1 has type uint64; k == 1<<33
+	m int   = 1.0 << s       // legal: 1.0 has type int
+	w int64 = 1.0 << 33      // legal: 1.0<<33 is a constant shift expression
+)
+
+// non-constant shift expressions
+var (
+	a1 int = 2.0 << s    // typeof(2.0) is int in this context => legal shift
+	d1     = f(2.0 << s) // typeof(2.0) is int in this context => legal shift
+)
+
+// constant shift expressions
+const c uint = 5
+
+var (
+	a2 int     = 2.0 << c    // a2 == 64 (type int)
+	b2         = 2.0 << c    // b2 == 64 (untyped integer)
+	_          = f(b2)       // verify b2 has type int
+	c2 float64 = 2 << c      // c2 == 64.0 (type float64)
+	d2         = f(2.0 << c) // == f(64)
+	e2         = g(2.0 << c) // == g(int(64))
+	f2         = h(2 << c)   // == h(float64(64.0))
+)