https://issues.dlang.org/show_bug.cgi?id=24221

          Issue ID: 24221
           Summary: Stable sort crash
           Product: D
           Version: D2
          Hardware: x86_64
                OS: Linux
            Status: NEW
          Severity: major
          Priority: P1
         Component: phobos
          Assignee: nobody@puremagic.com
          Reporter: john.loughran.colvin@gmail.com

Created attachment 1898
  --> https://issues.dlang.org/attachment.cgi?id=1898&action=edit
the code to trigger the crash

I know this predicate is weird and almost certainly isn't what the user wanted. I am reporting the crash & wondering if the predicate is "allowed".

predicate:

(x, y) => x.a < y.a && x.b < y.b;

data type:

Tuple!(string, "a", string, "b")[];

data length:

129

I reduced it from a longer array, but any smaller and the problem stops.

Please find code attached.

Error output:

core.exception.ArrayIndexError@/home/john/dlang/dmd-2.105.2/linux/bin64/../../src/phobos/std/algorithm/sorting.d(2755): index [18446744073709551615] is out of bounds for array of length 1
----------------
??:? onArrayIndexError [0x55b9bdd1bc26]
??:? _d_arraybounds_indexp [0x55b9bdd1bbe3]
??:? pure @safe ulong
std.algorithm.sorting.TimSortImpl!(crash.main().__lambda1,
immutable(char)[][][]).mergeHi!().mergeHi(immutable(char)[][][],
immutable(ulong), ulong, immutable(char)[][][]) [0x55b9bdcfd051]
??:? pure @safe void std.algorithm.sorting.TimSortImpl!(crash.main().__lambda1,
immutable(char)[][][]).merge!().merge(immutable(char)[][][], ulong, ref ulong,
ref immutable(char)[][][]) [0x55b9bdcfbeb9]
??:? pure @safe void std.algorithm.sorting.TimSortImpl!(crash.main().__lambda1,
immutable(char)[][][]).mergeAt!().mergeAt(immutable(char)[][][],
std.algorithm.sorting.TimSortImpl!(crash.main().__lambda1,
immutable(char)[][][]).Slice[], immutable(ulong), ref ulong, ref
immutable(char)[][][]) [0x55b9bdcfbb24]
??:? pure @safe void std.algorithm.sorting.TimSortImpl!(crash.main().__lambda1,
immutable(char)[][][]).sort!().sort(immutable(char)[][][],
immutable(char)[][][]) [0x55b9bdcfab62]
??:? pure @safe std.range.SortedRange!(immutable(char)[][][],
crash.main().__lambda1, 0).SortedRange
std.algorithm.sorting.sort!(crash.main().__lambda1, 2,
immutable(char)[][][]).sort(immutable(char)[][][]) [0x55b9bdcfa11e]
??:? _Dmain [0x55b9bdcf9f01]

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