Better error message when the compiler runs out of stack

[madhuvenu]

Hi,

I am new to rust and was trying to write a simple program when I ran into this failure. The failure message with backtrace enabled is as follows :

RUST_LOG=rustc=1,::rt::backtrace rustc list.rs
rust: task 7f8a7b415f20 ran out of stack
error: internal compiler error: unexpected failure
note: the compiler hit an unexpected failure path. this is a bug
note: try running with RUST_LOG=rustc=1,::rt::backtrace to get further details and report the results to github.com/mozilla/rust/issues
rust: task failed at 'explicit failure', /private/tmp/rust-xCH0/rust-0.6/src/librustc/rustc.rc:357
rust: domain main @0x7f8a7b815e10 root task failed

The source code that gets the compiler to fail is pasted below. I realize that I made a mistake by not making the "next" field an owned pointer in the structure below. Correcting this by making "next" an owned pointer using Option<~Node> fixes the problem.

struct Node {
  number : uint,
  next : Option<Node>
}

fn main() {

  let mut head = Node{ number : 0, next : None };
  let mut node  = Node{ number : 10, next : None };
  head.next = Some( node );
}

Is this expected ? Can the compiler instead catch such mistakes instead of running out of stack.

Thanks,
Madhu

[bstrie]

What platform are you on and what version of the compiler are you using? When I run the example, I get this instead:

$ rustc 6455.rs
6455.rs:9:10: 9:14 warning: variable does not need to be mutable [-W unused_mut]
6455.rs:9   let mut node  = Node{ number : 10, next : None };
                    ^~~~
Aborted

Which is still bad, but not as bad as an ICE. I'll change the title of this bug to represent that this is a diagnostic error.

[huonw]

@bstrie It still crashes, but silently:

$ RUST_LOG=::rt::backtrace rustc 6455.rs
6455.rs:9:10: 9:14 warning: variable does not need to be mutable [-W unused_mut]
6455.rs:9   let mut node  = Node{ number : 10, next : None };
                    ^~~~
rust: task 7f6068204720 ran out of stack

[metajack]

@bstrie It looks to me like that warning is just fine. There's no reason for node to be mut since it is never modified.

[jdm]

The error here has been reported many other times - the compiler doesn't do a good job of dealing with self-referential types and goes into a tailspin. Duplicate of #4363.