is this a bug with writeln / std.algorithm.remove?

[bauss]

On Friday, 16 February 2018 at 13:08:09 UTC, bauss wrote:
> On Friday, 16 February 2018 at 12:15:07 UTC, arturg wrote:
>> On Friday, 16 February 2018 at 11:45:21 UTC, arturg wrote:
>>> this code fails to compile:
>>>
>>>     void delegate(void*) dg;
>>>     void delegate(void*)[] dgs = [dg, dg, dg];
>>>     dgs.writeln;
>>>     dgs.remove(1).writeln();
>>>
>>> if you comment out dgs.writeln; it works as expected,
>>> it works if you use other types then void*:
>>>
>>>     void delegate(int*) dg;
>>>     void delegate(int*)[] dgs = [dg, dg, dg];
>>>     dgs.writeln;
>>>     dgs.remove(1).writeln();
>>>
>>>
>>> the compiler is DMD64 D Compiler v2.078.2 and the error 
>>> message is:
>>>
>>> /usr/include/dlang/dmd/std/algorithm/mutation.d(1929): Error: 
>>> template std.algorithm.mutation.moveAll cannot deduce 
>>> function from argument types !()(void delegate(void*)[], void 
>>> delegate(void*)[]), candidates are:
>>> /usr/include/dlang/dmd/std/algorithm/mutation.d(1455):        
>>> std.algorithm.mutation.moveAll(InputRange1, 
>>> InputRange2)(InputRange1 src, InputRange2 tgt) if 
>>> (isInputRange!InputRange1 && isInputRange!InputRange2 && 
>>> is(typeof(move(src.front, tgt.front))))
>>> empty.d(9): Error: template instance 
>>> std.algorithm.mutation.remove!(cast(SwapStrategy)2, void 
>>> delegate(void*)[], int) error instantiating
>>
>> running all dmd version on run.dlang.io
>> gives me this output:
>>
>> Up to      2.075.1: Success with output:
>> -----
>> [void delegate(void*), void delegate(void*), void 
>> delegate(void*)]
>> [void delegate(void*), void delegate(void*)]
>> -----
>>
>> Since      2.076.1: Failure with output:
>> -----
>> /path/to/dmd.linux/dmd2/linux/bin64/../../src/phobos/std/algorithm/mutation.d(1929): Error: template std.algorithm.mutation.moveAll cannot deduce function from argument types !()(void delegate(void*)[], void delegate(void*)[]), candidates are:
>> /path/to/dmd.linux/dmd2/linux/bin64/../../src/phobos/std/algorithm/mutation.d(1455):        std.algorithm.mutation.moveAll(InputRange1, InputRange2)(InputRange1 src, InputRange2 tgt) if (isInputRange!InputRange1 && isInputRange!InputRange2 && is(typeof(move(src.front, tgt.front))))
>> onlineapp.d(7): Error: template instance 
>> std.algorithm.mutation.remove!(cast(SwapStrategy)2, void 
>> delegate(void*)[], int) error instantiating
>> -----
>
> It's definitely a bug, the question is what change has caused 
> it.

Looking at "moveAll" which is the one that causes the error, no 
changes has been made to that which could cause this as within 
the last 3 months only changes made to it has been two asserts 
that has been inserted. Other than that has only been a 
documentation change a year ago and prior to that changes hasn't 
been made to it for 3 years.

So it's a bug in the compiler, rather than Phobos itself.