```
import std.stdio;

@safe:

__gshared int gshared = 42;

void foo(int i = gshared)
{
    writeln(i);
}

void main()
{
    foo();
}
```

This currently works; `foo` is `@safe` and prints the value of `gshared`. Changing the call in main to `foo(gshared)` errors.

Should it work, and can I expect it to keep working?

On Wednesday, 8 April 2020 at 16:53:05 UTC, Anonymouse wrote:
> ```
> import std.stdio;
>
> @safe:
>
> __gshared int gshared = 42;
>
> void foo(int i = gshared)
> {
>     writeln(i);
> }
>
> void main()
> {
>     foo();
> }
> ```
>
> This currently works; `foo` is `@safe` and prints the value of `gshared`. Changing the call in main to `foo(gshared)` errors.
>
> Should it work, and can I expect it to keep working?

According to the manual it shouldn't work at all https://dlang.org/spec/function.html#function-safety where it says Safe Functions: "Cannot access __gshared variables.", I don't know why calling as `foo()` works.

On Wednesday, 8 April 2020 at 18:50:16 UTC, data pulverizer wrote:
> On Wednesday, 8 April 2020 at 16:53:05 UTC, Anonymouse wrote:
>> ```
>> import std.stdio;
>>
>> @safe:
>>
>> __gshared int gshared = 42;
>>
>> void foo(int i = gshared)
>> {
>>     writeln(i);
>> }
>>
>> void main()
>> {
>>     foo();
>> }
>> ```
>>
>> This currently works; `foo` is `@safe` and prints the value of `gshared`. Changing the call in main to `foo(gshared)` errors.
>>
>> Should it work, and can I expect it to keep working?
>
> According to the manual it shouldn't work at all https://dlang.org/spec/function.html#function-safety where it says Safe Functions: "Cannot access __gshared variables.", I don't know why calling as `foo()` works.

You still wouldn't be able to manipulate gshared within the function. Though it may still be a problem for @safe...

import std.stdio;

__gshared int gshared = 42;

@safe void foo(int i = gshared)
{
    i++;
    writeln(i);
}

void main()
{
    writeln(gshared);
    foo();
    writeln(gshared);
    gshared++;
    writeln(gshared);
    foo();
    writeln(gshared);
}

On Wednesday, 8 April 2020 at 19:22:11 UTC, jmh530 wrote:
> On Wednesday, 8 April 2020 at 18:50:16 UTC, data pulverizer wrote:
>> On Wednesday, 8 April 2020 at 16:53:05 UTC, Anonymouse wrote:
>>> ```
>>> import std.stdio;
>>>
>>> @safe:
>>>
>>> __gshared int gshared = 42;
>>>
>>> void foo(int i = gshared)
>>> {
>>>     writeln(i);
>>> }
>>>
>>> void main()
>>> {
>>>     foo();
>>> }
>>> ```
>>>
>>> This currently works; `foo` is `@safe` and prints the value of `gshared`. Changing the call in main to `foo(gshared)` errors.
>>>
>>> Should it work, and can I expect it to keep working?
>>
>> According to the manual it shouldn't work at all https://dlang.org/spec/function.html#function-safety where it says Safe Functions: "Cannot access __gshared variables.", I don't know why calling as `foo()` works.
>
> You still wouldn't be able to manipulate gshared within the function. Though it may still be a problem for @safe...

It works with `ref int` too.


```
__gshared int gshared = 42;

void foo(ref int i = gshared) @safe
{
    ++i;
}
void main()
{
    assert(gshared == 42);
    foo();
    assert(gshared == 43);
}
```

On Wednesday, 8 April 2020 at 19:29:17 UTC, Anonymouse wrote:
> [snip]
>
> It works with `ref int` too.
>
>
> ```
> __gshared int gshared = 42;
>
> void foo(ref int i = gshared) @safe
> {
>     ++i;
> }
> void main()
> {
>     assert(gshared == 42);
>     foo();
>     assert(gshared == 43);
> }
> ```

Well that definitely shouldn't happen. I would file a bug report.

On Wednesday, 8 April 2020 at 19:29:17 UTC, Anonymouse wrote:
> ```
> __gshared int gshared = 42;
>
> void foo(ref int i = gshared) @safe
> {
>     ++i;
> }
> void main()
> {
>     assert(gshared == 42);
>     foo();
>     assert(gshared == 43);
> }
> ```

Dude, you just broke `@safe`! Lol!

On Wednesday, 8 April 2020 at 19:53:03 UTC, jmh530 wrote:
> Well that definitely shouldn't happen. I would file a bug report.

Filed as https://issues.dlang.org/show_bug.cgi?id=20726