On Tuesday, 25 March 2014 at 17:57:33 UTC, Atila Neves wrote:
I just spent a lot of time trying to debug my code and it seems
to have to do with @safe. I have some template functions in a
class, and one of them, marked as @safe, ended up making a call
to an abstract function with no attribute. My unit test started
failing and I tried writeln-debugging but now my function never
seemed to get called.
I tried gdb but the code jumped around weirdly (even though it
was a debug build) and some stack frame information was off so
I didn't trust it.
But stepping through the code gave me the idea to put writelns
earlier in the call stack, and as I did so I ran into a
compiler error I hadn't gotten before: @safe functions can't
call writeln. "Fair enough", I said, and ended up with a chain
of functions that had to be changed.
And then my code worked again. So I removed the writelns,
changed everything to @trusted, and... the code worked again. I
narrowed the fix down to this:
https://github.com/atilaneves/cerealed/commit/09d278638394185339a6115e7093b8aab2fac480
So, because an abstract function wasn't @safe, the compiler
emitted code to... I'm not quite sure to do what. All I know is
it didn't call the right function.
Is there something about @safe, @trusted, etc. that causes the
compiler to disregard template functions from instantiation??
The worst part of all this is the compiler said not one thing.
And it took a while to track down. I nearly wish I hadn't
bothered with @safe and friends!
Atila
I don't know the answer to your problem, but I wanted to mention
that you *can* call @system functions in an @safe function if you
use debug. It's extremely handy so you DON'T have to change a
huge chain of functions like you did.
@safe void main()
{
import std.stdio;
//Okay, writeln is in a debug block
debug writeln("Test");
}
