Function pointers and lifetimes : 2014-07-24 -> 2014-07-26

[artella-coding]

In going from rustc 0.12.0-pre-nightly (2224edcfe 2014-07-24 00:26:14 +0000) to rustc 0.12.0-pre-nightly (cf1381c1d 2014-07-26 00:46:16 +0000), a certain symmetry breaking seems to have arisen and I want to check that this is not a bug.

The following code works in both nighty :

static myval: int = 5;

struct cls<'a>{
  z: &'a int
}

fn create<'r>() -> cls<'r> {
  cls { z : & myval }
}

fn main(){}

However the following code, which is a "functionised" version of the above example, fails in the 2014-07-26 nightly but not in the 2014-07-24 nightly.

fn retn() -> int{ return 5; }

struct cls<'a>{
  fz: &'a fn() -> int
}
/*
error: borrowed value does not live long enough
       cls { fz : & retn }
                    ^~~~
*/
fn create<'r>() -> cls<'r> {
  cls { fz : & retn }
}

fn main(){}

I don't understand why the latter should not work, since if I am not mistaken, the scope of the function fn retn() is the same as the scope of static myval: int. Thanks

[bluss]

It changed in #15961. You should be able to just use the fn() -> int type which is already a copyable function pointer.

[artella-coding]

@blake2-ppc Ah Patrick's post explains that the above is a breaking change. Thanks!