Accessing enum' or static' member allocates gc closure

[dlangBugzillaToGithub]

timon.gehr reported this on 2017-09-04T10:01:46Z

Transferred from https://issues.dlang.org/show_bug.cgi?id=17804

CC List

Description

struct S{
    enum n=1;
}
struct T{
    static n=1;
}

void foo(S v)@nogc{
    auto f=()=>v.n; // error
}
void bar(T v)@nogc{
    auto f=()=>v.n; // error
}

This code should compile.

Also see issue 17800.

[dlangBugzillaToGithub]

asumface commented on 2019-03-16T21:34:03Z

To add to this, consider the following code:

import std.algorithm;
struct Foo
{
    static int fun(int n)
    {
    	return n + 1;
    }
}

void main()
{
    int[10] arr;
    Foo foo;
    arr[].map!(n => foo.fun(n));
}

the line
    arr[].map!(n => foo.fun(n));
causes GC allocation, whereas the same line with foo replaced with its type
    arr[].map!(n => Foo.fun(n));
does not. This is despite the functionality being absolutely identical as fun has no dependency on 'this' whatsoever due to being a static member.