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Source file test/shift2.go

Documentation: test

  // compile
  
  // 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.
  
  // Test legal shifts.
  // Issue 1708, legal cases.
  // Compiles but does not run.
  
  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
  	l       = g(1 << s)      // 1 has type int
  	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))
  )
  

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