[Issue 14340] New: AssertError in std.algorithm.sorting: unstable sort fails to sort an array with a custom predicate

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=14340

          Issue ID: 14340
           Summary: AssertError in std.algorithm.sorting: unstable sort
                    fails to sort an array with a custom predicate
           Product: D
           Version: D2
          Hardware: All
                OS: Windows
            Status: NEW
          Severity: major
          Priority: P1
         Component: Phobos
          Assignee: nobody at puremagic.com
          Reporter: gassa at mail.ru

Created attachment 1497
  --> https://issues.dlang.org/attachment.cgi?id=1497&action=edit
example code

This example code, compiled with -debug, triggers an AssertError.

-----
import std.algorithm, std.conv, std.range, std.stdio;
void main () {
    auto arr = [7, 5, 7, 3, 3, 5, 3, 3, 0, 3, 1, 1, 5, 1, 
1, 1, 2, 2, 8, 5, 8, 8];
    arr.sort !((x, y) => arr.count (x) > arr.count (y) ||
        (arr.count (x) == arr.count (y) && x < y))
        .map !(to !(string))
        .join (" ")
        .writeln;
    // prints 1 1 1 1 1 3 3 3 3 3 5 5 5 5 8 8 8 2 2 0 7 7
    // should 1 1 1 1 1 3 3 3 3 3 5 5 5 5 8 8 8 2 2 7 7 0
}
-----

Reproducible on Win64 with DMD 2.066 or 2.067, -m32 or -m64.
Without -debug, it produces wrong output with -m32 and crashes with -m64.

The D.learn discussion resulting in this example:
http://forum.dlang.org/thread/fqbojlyocmsovrpzilhu@forum.dlang.org

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