gcc/testsuite/gdc.test/fail_compilation/test8556.d

   1 /*
   2 TEST_OUTPUT:
   3 ---
   4 fail_compilation/test8556.d(24): Error: template instance `test8556.Grab!(Circle!(uint[]))` does not match template declaration `Grab(Range)`
   5   with `Range = Circle!(uint[])`
   6   must satisfy the following constraint:
   7 `       !isSliceable!Range`
   8 fail_compilation/test8556.d(55): Error: template instance `test8556.grab!(Circle!(uint[]))` error instantiating
   9 ---
  10 */
  11
  12 extern(C) int printf(const char*, ...);
  13
  14 template isSliceable(R)
  15 {
  16     enum bool isSliceable = is(typeof( R.init[1 .. 2] ));
  17 }
  18
  19 struct Grab(Range) if (!isSliceable!Range)
  20 {
  21     public Range source;
  22 }
  23
  24 Grab!R grab(R)(R input)
  25 {
  26     return Grab!R(input);
  27 }
  28
  29 // 3. evaluate isSliceable in template constraint
  30 auto grabExactly(R)(R range) if (!isSliceable!R) { return 0; }
  31 auto grabExactly(R)(R range) if ( isSliceable!R) { return 0; }
  32
  33 struct Circle(Range)
  34 {
  35     // 2. auto return opSlice
  36     auto opSlice(size_t i, size_t j)
  37     {
  38         //pragma(msg, typeof(opSlice)); // prints "fwdref err" with B, but doesn't with A
  39
  40         printf("%d %d\n", cast(int)i, cast(int)j);
  41         assert(j >= i);
  42
  43         // 1. grabExactly curcular refers this opSlice.
  44         return grabExactly(typeof(this)());     // broken execution with A
  45     }
  46 }
  47
  48 Circle!R circle(R)()
  49 {
  50     return Circle!R();
  51 }
  52
  53 void main()
  54 {
  55     auto t = grab(circle!(uint[])());
  56
  57     auto cx = circle!(uint[])();
  58     auto slice = cx[23 .. 33];
  59 }