This very very simple function [1] won't compile.
It says that param t is not nothrow. Why? What's wrong with this?

http://dpaste.dzfl.pl/bfc382e62711

On Tuesday, 1 March 2016 at 13:35:08 UTC, Andrea Fontana wrote:
> This very very simple function [1] won't compile.
> It says that param t is not nothrow. Why? What's wrong with this?
>
> http://dpaste.dzfl.pl/bfc382e62711

writeln isn't nothrow so you can't call it from test which is nothrow without a try .. catch.
The error message is misleading.

On 01.03.2016 14:35, Andrea Fontana wrote:
> This very very simple function [1] won't compile.
> It says that param t is not nothrow. Why? What's wrong with this?
>
> http://dpaste.dzfl.pl/bfc382e62711

It's a bug. Lazy parameters generate delegates. nothrow is currently not inferred for those delegates. It should be.

https://issues.dlang.org/show_bug.cgi?id=12647

On Tuesday, 1 March 2016 at 13:41:38 UTC, Nemo wrote:
> On Tuesday, 1 March 2016 at 13:35:08 UTC, Andrea Fontana wrote:
>> This very very simple function [1] won't compile.
>> It says that param t is not nothrow. Why? What's wrong with this?
>>
>> http://dpaste.dzfl.pl/bfc382e62711
>
> writeln isn't nothrow so you can't call it from test which is nothrow without a try .. catch.
> The error message is misleading.

You are right about writeln & nothrow but the problem is still there if instead of:

writeln(t);

you write:

t;

(that's a reduced example, in real code I don't use writeln or other non-nothrow functions)