[Issue 6747] Implicitly allowing objects which contain delegates to be shared/immutable can cause races

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=6747

mhh <maxhaton at gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |maxhaton at gmail.com
           Severity|enhancement                 |normal

--- Comment #1 from mhh <maxhaton at gmail.com> ---
Still a problem BUT @safe does catch the problem in it.

https://d.godbolt.org/z/Px5aTM


------------------

import std.algorithm;
import std.stdio;
import std.traits;
class Foo //@safe can catch the bug with ref
{
   immutable this(ref int _i) 
   { 
       dg = (){++_i;}; 
   }
   void delegate() dg;
}

immutable Foo f;

int notShared;

shared static this()
{
   f = new immutable Foo(notShared);
}

void sharedInc(immutable Foo x)
{
        x.dg();
}

void main()
{
    import std.stdio;
    import std;
        f.dg();
    f.dg();
    f.dg();
    auto file1Task = task!sharedInc(f);
    file1Task.executeInNewThread();

    // Read bar.txt in parallel.
    sharedInc(f);

    // Get the results of reading foo.txt.
    file1Task.yieldForce;
}

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