Simple File test:

    void main()
    {
        import std.stdio;

        File f = File("test.txt", "w");

        f.writeln("hello");
    }

All works as expected.

Now let's add __gshared:

    void main()
    {
        import std.stdio;

        __gshared File f = File("test.txt", "w");

        f.writeln("hello");
    }

Now we have:

/usr/include/dmd/phobos/std/stdio.d(3797): Error: fopen64 cannot be interpreted at compile time, because it has no available source code
/usr/include/dmd/phobos/std/stdio.d(3804):        called from here: fopenImpl(namez.ptr(), modez.ptr())
/usr/include/dmd/phobos/std/stdio.d(404):        called from here: fopen(name, stdioOpenmode)
/usr/include/dmd/phobos/std/stdio.d(404):        called from here: errnoEnforce(fopen(name, stdioOpenmode), delegate string() => text("Cannot open file `", name, "' in mode `", stdioOpenmode, "'"))
/usr/include/dmd/phobos/std/stdio.d(404):        called from here: this.this(errnoEnforce(fopen(name, stdioOpenmode), delegate string() => text("Cannot open file `", name, "' in mode `", stdioOpenmode, "'")), name, 1u, false)
file.d(5):        called from here: ((File __slFile648 = File(null, null);) , __slFile648).this("test.txt", "w")

Oooops! Who can explain this error message to me?

DMD64 D Compiler v2.073.0

On Saturday, 25 March 2017 at 15:52:15 UTC, crimaniak wrote:
> Simple File test:
>
>     void main()
>     {
>         import std.stdio;
>
>         File f = File("test.txt", "w");
>
>         f.writeln("hello");
>     }
>
> All works as expected.
>
> Now let's add __gshared:
>
>     void main()
>     {
>         import std.stdio;
>
>         __gshared File f = File("test.txt", "w");
>
>         f.writeln("hello");
>     }
>
> Now we have:
>
> /usr/include/dmd/phobos/std/stdio.d(3797): Error: fopen64 cannot be interpreted at compile time, because it has no available source code
> /usr/include/dmd/phobos/std/stdio.d(3804):        called from here: fopenImpl(namez.ptr(), modez.ptr())
> /usr/include/dmd/phobos/std/stdio.d(404):        called from here: fopen(name, stdioOpenmode)
> /usr/include/dmd/phobos/std/stdio.d(404):        called from here: errnoEnforce(fopen(name, stdioOpenmode), delegate string() => text("Cannot open file `", name, "' in mode `", stdioOpenmode, "'"))
> /usr/include/dmd/phobos/std/stdio.d(404):        called from here: this.this(errnoEnforce(fopen(name, stdioOpenmode), delegate string() => text("Cannot open file `", name, "' in mode `", stdioOpenmode, "'")), name, 1u, false)
> file.d(5):        called from here: ((File __slFile648 = File(null, null);) , __slFile648).this("test.txt", "w")
>
> Oooops! Who can explain this error message to me?
>
> DMD64 D Compiler v2.073.0

__gshared implies static, that is, known at compile time (ct), that means the File constructor should be done at ct and thus open the file. Compile time function execution doesn't allow IO operations, however you can use https://dlang.org/spec/expression.html#ImportExpression if you want to read a file at compile time.

On Saturday, 25 March 2017 at 16:08:49 UTC, NotSpooky wrote:

> __gshared implies static,...

Thanks! Confusing for me moment.

On Saturday, 25 March 2017 at 16:46:00 UTC, crimaniak wrote:
> On Saturday, 25 March 2017 at 16:08:49 UTC, NotSpooky wrote:
>
>> __gshared implies static,...
>
> Thanks! Confusing for me moment.

try this:

import std.stdio;

    void main()
    {
        import std.stdio;

        __gshared File f;
	f = File("test.txt", "w");

        f.writeln("hello");
    }