[Issue 17019] New: std.algorithm.iteration.each should be usable with parallel

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=17019

          Issue ID: 17019
           Summary: std.algorithm.iteration.each should be usable with
                    parallel
           Product: D
           Version: D2
          Hardware: x86_64
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P1
         Component: phobos
          Assignee: nobody at puremagic.com
          Reporter: greeenify at gmail.com

The following test fails:

```
unittest
{
    import std.algorithm.iteration : each, sum;
    import std.parallelism : parallel;
    import std.range : iota;

    auto logsIndex = new int[10];
    parallel(logsIndex).each!((i, ref e) => e += i);
    assert(logsIndex.sum == 10.iota.sum);
}
```

while it passes without parallel:

```
unittest
{
    import std.algorithm.iteration : each, sum;
    import std.parallelism : parallel;
    import std.range : iota;

    auto logsIndex = new int[10];
    logsIndex.each!((i, ref e) => e += i);
    assert(logsIndex.sum == 10.iota.sum);
}
```

of course the foreach alternative works as well

```
unittest
{
    import std.algorithm.iteration : sum;
    import std.parallelism : parallel;
    import std.range : iota;

    auto logsIndex = new int[10];
    foreach (i, ref e; parallel(logsIndex))
        e += i;
    assert(logsIndex.sum == 10.iota.sum);
}
```

/usr/include/dlang/dmd/std/algorithm/iteration.d(936): Error: template
foo.__unittestL1_3.__lambda1 cannot deduce function from argument types
!()(int), candidates are:
foo.d(8):        foo.__unittestL1_3.__lambda1
foo.d(8): Error: template instance foo.__unittestL1_3.each!((i, ref e) => e +=
i).each!(ParallelForeach!(int[])) error instantiating
Failed: ["dmd", "-unittest", "-g", "-v", "-c",
"-of/tmp/.rdmd-1000/rdmd-foo.d-2E6138563669BF9753765C098C72200E/objs/foo.o",
"foo.d", "-I.", "/tmp/.rdmd-1000/stubmain.d"]


This is probably related to https://issues.dlang.org/show_bug.cgi?id=15357

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