• Oleg B (5/5) Oct 03 2019 Hello all
• Adam D. Ruppe (8/10) Oct 03 2019 Indeed, the spec allows the compiler to issue an error, but
• Daniel Kozak (24/29) Oct 03 2019 when you change it a litle it seems works ok:

Oleg B <code.viator gmail.com> writes:

Hello all

I think this code must get compilation error, but it didn't, 
furthermore result program get UB.

https://run.dlang.io/is/Qpr278

Is this correct behavior and why?

Adam D. Ruppe <destructionator gmail.com> writes:

On Thursday, 3 October 2019 at 11:56:55 UTC, Oleg B wrote:
 I think this code must get compilation error, but it didn't, 
 furthermore result program get UB.

Indeed, the spec allows the compiler to issue an error, but 
doesn't require it. tbh it was due to difficulty in implementing 
the compile time error back when it was designed, so Walter kept 
the spec flexible.

If you mark the function as  safe now, you will get a compile 
error on it now. But without that annotation, the compiler keeps 
its older, looser behavior.

Daniel Kozak <kozzi11 gmail.com> writes:

On Thu, Oct 3, 2019 at 2:00 PM Oleg B via Digitalmars-d-learn
<digitalmars-d-learn puremagic.com> wrote:
 Hello all

 I think this code must get compilation error, but it didn't,
 furthermore result program get UB.

 https://run.dlang.io/is/Qpr278

 Is this correct behavior and why?

when you change it a litle it seems works ok:

import std.stdio;
struct Foo
{
    int delegate() dg;
    void foo(return scope int delegate() dg)
    {
        this.dg = dg;
    }
    int call() { return dg(); }
}

Foo getFoo()
{
    int x = 42;
    Foo ret;
    ret.foo(() => x);
    return ret;
}

void main()
{
    writeln(getFoo().call());
}