• H. S. Teoh via Digitalmars-d (22/22) Aug 09 2014 Here's a lovely Saturday morning exercise for you D aficionados out
• Timon Gehr (10/12) Aug 09 2014 My guess is it is just a missing diagnostic for the missing support for
• H. S. Teoh via Digitalmars-d (7/25) Aug 09 2014 Aha! I think you're right. Moving declaration into main() and changing

"H. S. Teoh via Digitalmars-d" <digitalmars-d puremagic.com> writes:

Here's a lovely Saturday morning exercise for you D aficionados out
there:

	struct S(alias fun)
	{
	    auto g() { return fun(0); }
	}

	auto f(int arr)
	{
	    return S!(a => arr)();
	}

	auto r = f(2);

	void main() {
	    r.g();
	}

This causes a segfault at runtime. Moving the declaration of r inside
main() fixes the problem. Why?

	https://issues.dlang.org/show_bug.cgi?id=11826

My suspicion is that the lambda is trying to access the local variable
'arr', which has gone out of scope.


T

-- 
Leather is waterproof.  Ever see a cow with an umbrella?

Timon Gehr <timon.gehr gmx.ch> writes:

On 08/09/2014 07:11 PM, H. S. Teoh via Digitalmars-d wrote:
 This causes a segfault at runtime. Moving the declaration of r inside
 main() fixes the problem. Why?

My guess is it is just a missing diagnostic for the missing support for 
closures in CTFE.

You are effectively trying to do something like

auto foo(int a){
     return (int x)=>x+a;
}
auto d=foo(2);

which fails with

Error: closures are not yet supported in CTFE

"H. S. Teoh via Digitalmars-d" <digitalmars-d puremagic.com> writes:

On Sat, Aug 09, 2014 at 07:39:51PM +0200, Timon Gehr via Digitalmars-d wrote:
 On 08/09/2014 07:11 PM, H. S. Teoh via Digitalmars-d wrote:
This causes a segfault at runtime. Moving the declaration of r inside
main() fixes the problem. Why?

 
 My guess is it is just a missing diagnostic for the missing support
 for closures in CTFE.
 
 You are effectively trying to do something like
 
 auto foo(int a){
     return (int x)=>x+a;
 }
 auto d=foo(2);
 
 which fails with
 
 Error: closures are not yet supported in CTFE

Aha! I think you're right. Moving declaration into main() and changing
it to enum (to force CTFE) causes the same problem. So, looks like it's
a missing check for an unsupported feature in CTFE.


T

-- 
Shin: (n.) A device for finding furniture in the dark.