• via Digitalmars-d-bugs (47/47) Nov 20 2016 https://issues.dlang.org/show_bug.cgi?id=16705

via Digitalmars-d-bugs <digitalmars-d-bugs puremagic.com> writes:

https://issues.dlang.org/show_bug.cgi?id=16705

          Issue ID: 16705
           Summary: TaskPool.reduce fails to compile "cannot get frame
                    pointer to D main"
           Product: D
           Version: D2
          Hardware: x86_64
                OS: Mac OS X
            Status: NEW
          Severity: normal
          Priority: P1
         Component: phobos
          Assignee: nobody puremagic.com
          Reporter: mihai unity3d.com

The synopsis code from https://dlang.org/phobos/std_parallelism.html generates
a "cannot get frame pointer" compile error:

/Library/D/dmd/src/phobos/std/parallelism.d(2633): Error: function
std.parallelism.TaskPool.reduce!"a + b".reduce!(MapResult!(getTerm,
Result)).reduce cannot get frame pointer to D main

```d
import std.algorithm, std.parallelism, std.range;

void main() {
    // Parallel reduce can be combined with
    // std.algorithm.map to interesting effect.
    // The following example (thanks to Russel Winder)
    // calculates pi by quadrature  using
    // std.algorithm.map and TaskPool.reduce.
    // getTerm is evaluated in parallel as needed by
    // TaskPool.reduce.
    //
    // Timings on an Athlon 64 X2 dual core machine:
    //
    // TaskPool.reduce:       12.170 s
    // std.algorithm.reduce:  24.065 s

    immutable n = 1_000_000_000;
    immutable delta = 1.0 / n;

    real getTerm(int i)
    {
        immutable x = ( i - 0.5 ) * delta;
        return delta / ( 1.0 + x * x ) ;
    }

    immutable pi = 4.0 * taskPool.reduce!"a + b"(
        std.algorithm.map!getTerm(iota(n))
    );
}
```

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