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digitalmars.D.bugs - [Issue 17084] New: Can't sort array of structs with alias this: swap

https://issues.dlang.org/show_bug.cgi?id=17084

          Issue ID: 17084
           Summary: Can't sort array of structs with alias this: swap
                    can't call non- nogc function doesPointTo
           Product: D
           Version: D2
          Hardware: x86_64
                OS: Windows
            Status: NEW
          Severity: enhancement
          Priority: P1
         Component: phobos
          Assignee: nobody puremagic.com
          Reporter: dhasenan gmail.com

I have no clue what's going on.

Dustmite-minimized with some hand massaging:

---
import std.algorithm;

struct URL
{
    int[] queryParams;
    string toString() const { return ""; }
    alias toString this;
}

struct Page
{
    URL url;
    int opCmp(Page) { return 0; }
}

void main()
{
    Page[] s;
    std.algorithm.sort(s);
}
---

Removing 'alias this' fixes it. Making 'queryParams' not be an array fixes it.
(But putting the array in another struct does not.) Inlining the struct fixes
the error (incorporating the fields and methods from URL into Page).


Error:
---
/usr/include/dmd/phobos/std/algorithm/mutation.d(2183): Error:  nogc function
'std.algorithm.mutation.swap!(Page).swap' cannot call non- nogc function
'std.exception.doesPointTo!(Page, Page, void).doesPointTo'
/usr/include/dmd/phobos/std/algorithm/mutation.d(2184): Error:  nogc function
'std.algorithm.mutation.swap!(Page).swap' cannot call non- nogc function
'std.exception.doesPointTo!(Page, Page, void).doesPointTo'
/usr/include/dmd/phobos/std/algorithm/mutation.d(2185): Error:  nogc function
'std.algorithm.mutation.swap!(Page).swap' cannot call non- nogc function
'std.exception.doesPointTo!(Page, Page, void).doesPointTo'
/usr/include/dmd/phobos/std/algorithm/mutation.d(2186): Error:  nogc function
'std.algorithm.mutation.swap!(Page).swap' cannot call non- nogc function
'std.exception.doesPointTo!(Page, Page, void).doesPointTo'
/usr/include/dmd/phobos/std/algorithm/mutation.d(2009): Error: template
instance std.algorithm.mutation.swap!(Page) error instantiating
/usr/include/dmd/phobos/std/algorithm/sorting.d(1322):        instantiated from
here: swapAt!(Page[])
/usr/include/dmd/phobos/std/algorithm/sorting.d(1293):        instantiated from
here: siftDown!()
/usr/include/dmd/phobos/std/algorithm/sorting.d(1278):        instantiated from
here: buildHeap!()
/usr/include/dmd/phobos/std/algorithm/sorting.d(1217):        instantiated from
here: heapSort!()
/usr/include/dmd/phobos/std/algorithm/sorting.d(1047):        instantiated from
here: quickSortImpl!(binaryFun, Page[])
server.d(19):        instantiated from here: sort!("a < b",
cast(SwapStrategy)0, Page[])
/usr/include/dmd/phobos/std/algorithm/sorting.d(1283): Error: template instance
std.algorithm.sorting.HeapOps!(binaryFun, Page[]).percolate!() error
instantiating
/usr/include/dmd/phobos/std/algorithm/sorting.d(1217):        instantiated from
here: heapSort!()
/usr/include/dmd/phobos/std/algorithm/sorting.d(1047):        instantiated from
here: quickSortImpl!(binaryFun, Page[])
server.d(19):        instantiated from here: sort!("a < b",
cast(SwapStrategy)0, Page[])
/usr/include/dmd/phobos/std/algorithm/sorting.d(1222): Error: template instance
std.algorithm.sorting.getPivot!(binaryFun, Page[]) error instantiating
/usr/include/dmd/phobos/std/algorithm/sorting.d(1047):        instantiated from
here: quickSortImpl!(binaryFun, Page[])
server.d(19):        instantiated from here: sort!("a < b",
cast(SwapStrategy)0, Page[])
Failed: ["dmd", "-v", "-o-", "server.d", "-I."]
---

--
Jan 10