I would like to debug a few things and need to insert print statements to figure things out. I thought that using debug print would be ok in nogc code?

Seems it make the compiler infer f as not nogc though so this is basically unworkable unless I go through my entire source code and remove the @nogc attribute wherever function f is used.

Anyway around this?

Here's example code:

import std.stdio;

void f(T)(auto ref T) {
    debug writeln("yo");
}

@nogc void main() {
	f(3);
}

Error: @nogc function D main cannot call non-@nogc function onlineapp.f!int.f

Cheers,
- Ali

You can strip off any attribute with SetFunctionAttributes:

import std.stdio;

// Adapted from std.traits.SetFunctionAttributes documentation
import std.traits;
auto assumeNoGC(T)(T t)
    if (isFunctionPointer!T || isDelegate!T)
{
    enum attrs = functionAttributes!T | FunctionAttribute.nogc;
    return cast(SetFunctionAttributes!(T, functionLinkage!T, attrs)) t;
}

void f(T)(auto ref T) {
    writeln("yo");
}

@nogc void main() {
    assumeNoGC(() => f(3));
    // or
    assumeNoGC( { writeln("yo"); });
}

Ali

On Saturday, 1 September 2018 at 21:53:03 UTC, aliak wrote:
> Anyway around this?

I don't know if your situation allows it, but you can mark f explicitly as always @nogc. If your design assumes that it's @nogc, it's a good idea to add the attribute anyway.

You can also use the C printf function:
```
import core.stdc.stdio: printf;
printf("yo\n");
```

On Saturday, 1 September 2018 at 22:38:46 UTC, Ali Çehreli wrote:
> You can strip off any attribute with SetFunctionAttributes:
>
> import std.stdio;
>
> // Adapted from std.traits.SetFunctionAttributes documentation
> import std.traits;
> auto assumeNoGC(T)(T t)
>     if (isFunctionPointer!T || isDelegate!T)
> {
>     enum attrs = functionAttributes!T | FunctionAttribute.nogc;
>     return cast(SetFunctionAttributes!(T, functionLinkage!T, attrs)) t;
> }
>
> void f(T)(auto ref T) {
>     writeln("yo");
> }
>
> @nogc void main() {
>     assumeNoGC(() => f(3));
>     // or
>     assumeNoGC( { writeln("yo"); });
> }
>
> Ali

Ah this works! Can define a debugWriteln then that can be used from anywhere without having to re attribute all the functions.

Thanks!