Strange closure behaviour

[Adam D. Ruppe]

On Saturday, 15 June 2019 at 00:24:52 UTC, Emmanuelle wrote:
> Is it a compiler bug?

Yup, a very longstanding bug.

You can work around it by wrapping it all in another layer of 
function which you immediately call (which is fairly common in 
javascript):

         funcs ~= ((x) => (int i) { nums[x] ~= i; })(x);

Or maybe less confusingly written long form:

         funcs ~= (delegate(x) {
             return (int i) { nums[x] ~= i; };
         })(x);

You write a function that returns your actual function, and 
immediately calls it with the loop variable, which will 
explicitly make a copy of it.