[Issue 8847] New: voldemort + inout confuses "is"

[d-bugmail at puremagic.com]

http://d.puremagic.com/issues/show_bug.cgi?id=8847

           Summary: voldemort + inout confuses "is"
           Product: D
           Version: unspecified
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: major
          Priority: P2
         Component: DMD
        AssignedTo: nobody at puremagic.com
        ReportedBy: monarchdodra at gmail.com


--- Comment #0 from monarchdodra at gmail.com 2012-10-18 02:13:05 PDT ---
I discovered this inside phobos. First reduced test case:

//----
import std.stdio;
import std.range;
import std.conv;

void main()
{
    auto a = iota(1, 2);
    auto b = a[];
    alias typeof(a) A;
    alias typeof(b) B;
    writeln("Typeof A: ", A.stringof);
    writeln("Typeof B: ", B.stringof);
    assert(is(A == B), text(A.stringof, " is different from " , B.stringof));
}
//----
Typeof A: Result
Typeof B: Result
core.exception.AssertError at main.d(13): Result is different from Result
//----

Which is very strange. I found the root condition that recreates this: It is
having a voldemort function that is qualified with inout:

//----
import std.stdio;
import std.conv;

auto S()
{
    static struct Result
    {
      inout(Result) get() inout {return this;}
    }
    return Result();
}

void main()
{
    auto a = S();
    auto b = a.get();
    alias typeof(a) A;
    alias typeof(b) B;
    writeln("Typeof A: ", A.stringof);
    writeln("Typeof B: ", B.stringof);
    assert(is(A == B), text(A.stringof, " is different from " , B.stringof));
}
//----
Typeof A: Result
Typeof B: Result
core.exception.AssertError at main.d(21): Result is different from Result
//----

I'm marking this as major, because it is currently showing up in Phobos:
I wrote a fix for emplace, to bypass opAssign (which it should *not* be
calling), and it turns out there is an emplace that fails to build a
zip.opSlice because of this:

Pull: https://github.com/D-Programming-Language/phobos/pull/837
D2: http://d.puremagic.com/test-results/pull-history.ghtml?repoid=3&pullid=837

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