Why writeln can't be converted to nothrow with just catching of StdioException

[Mike Parker]

On Monday, 21 February 2022 at 11:07:55 UTC, Basile B. wrote:
>
> Yeah there must be another one then. Something actionnable is 
> the documentation.

This has nothing to do with which exceptions types a function 
throws. The compiler doesn't dig into that. You have to catch 
`Exception`.

```D
import std.stdio;

class MyException : Exception {
     this(string msg) { super(msg); }
}

void throwing(int x) {
     if(x > 2) throw new MyException("Derp!");
     else writeln(x);
}

void noThrowing() nothrow {
     try {
         throwing(10);
     }
     catch(MyException me) {}
}

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

```
onlineapp.d(14): Error: function `onlineapp.throwing` is not 
`nothrow`
onlineapp.d(12): Error: `nothrow` function `onlineapp.noThrowing` 
may throw
```