ICE with an `@mut ~[T]` vec

[alexcrichton]

This program:

struct A {
  bar: @mut ~[int],
}

impl A {
  fn foo(&self) -> int {
    match 3 {
      _ => if true {
        fail!()
      } else {
        *self.bar.last() // bug is from this line
      }
    }
  }
}

fn main() {}

Causes this output:

$ rustc foo.rs        
error: internal compiler error: no enclosing scope with id 31

I tried minimizing it further, but I was unable to get it any smaller.

[alexcrichton]

I managed to get it a little smaller without relying on vec::last

fn foo(self: &A) -> int {           
    if true {                       
        fail!()                     
    } else {                        
        *bar(self.bar)              
    }                               
}                                   

pub fn main() {}                    

fn bar(_: &'r mut int) -> &'r int {   
    fail!()                         
}                                   

struct A {                          
  bar: @mut int,                    
}                                   

[iansharkey]

Got the same error with this testcase:

enum A {
 L(@mut [A]),
//L(@ [A]),  <-- this compiles
}

impl Eq for A {
  fn eq(&self, other: &A) -> bool {
    match (self, other) {
      (&L(x), &L(y)) => (x == y)
    }
  }

  fn ne(&self, _: &A) -> bool {
    return false;
  }
}

fn main() {}

[emberian]

Updated testcase:

fn foo(self_: &A) -> int {           
    if true {                       
        fail!()                     
    } else {                        
        *bar(self_.bar)              
    }                               
}                                   

pub fn main() {}                    

fn bar<'r>(_: &'r mut int) -> &'r int {   
    fail!()                         
}                                   

struct A {                          
  bar: @mut int,                    
}                                   

[alexcrichton]

This has been fixed somewhere in the interim. Not quite sure where, but there were lots of changes to borrowck between when I opened this issue and now.

[emberian]

Needstest