Take the following code:

void main()
{
    shared class C { bool opEquals(const(shared(C)) rhs) const shared  { return true;}}
    const(C) c = new C();
    const(C)[] a = [c];
    const(C)[] b = [c];
    assert(a[0] == b[0]);
}

This code (supposedly) checks whether a and b are equal. The thing is, it doesn't, because C is defined as shared. Is there anything I can do to fix this?

On Wednesday, 10 August 2022 at 15:19:41 UTC, Ruby The Roobster wrote:

void main()
{
    shared class C { bool opEquals(const(shared(C)) rhs) const shared  { return true;}}
    const(C) c = new C();
    const(C)[] a = [c];
    const(C)[] b = [c];
    assert(a[0] == b[0]);
}

Wait, is this a regression?

Up to 2.098.1: Success and no output
Since 2.099.1: Failure with output:
-----
onlineapp.d(7): Error: none of the overloads of template object.opEquals are callable using argument types !()(shared(const(C)), shared(const(C)))
/path/to/dmd.linux/dmd2/linux/bin64/../../src/druntime/import/object.d(269): Candidate is: opEquals(LHS, RHS)(LHS lhs, RHS rhs)
with LHS = shared(const(C)), RHS = shared(const(C))
must satisfy the following constraint:
is(LHS : const(Object))
-----

On 8/10/22 11:26 AM, Ruby The Roobster wrote:

void main()
{
    shared class C { bool opEquals(const(shared(C)) rhs) const shared  { return true;}}
    const(C) c = new C();
    const(C)[] a = [c];
    const(C)[] b = [c];
    assert(a[0] == b[0]);
}

Yes. It's a druntime regression.

In the compiler, instances shared classes are now treated as if the variables were declared shared. Prior to this, they were just C. Druntime was not updated to reflect this.

A related bug: https://issues.dlang.org/show_bug.cgi?id=23140

-Steve

On Wednesday, 10 August 2022 at 15:50:45 UTC, Steven Schveighoffer wrote:

Funnily enough, I came across this when trying to fix that same bug.