Segfault in safe code while decoding JSON

[japaric]

STR

extern crate serialize;

use serialize::json;

#[deriving(Decodable)]
struct Interpreter {
    command: String,
    flags: Vec<String>,
    version: String,
}

static GOOD_INPUT: &'static str =
r#"{
    "command": "python3",
    "flags": ["-O"],
    "version": "--version"
}"#;

static BAD_INPUT: &'static str =
r#"{
    "command": "python3",
    "flags": ["-O"],
    "--version": "--version"
}"#;

fn main() {
    println!("Decoding GOOD_INPUT... ");
    let good = match json::decode::<Interpreter>(GOOD_INPUT) {
        Err(err) => fail!("{}", err),
        Ok(interpreter) => interpreter,
    };
    println!("> OK");

    println!("Decoding BAD_INPUT... ");
    let bad = match json::decode::<Interpreter>(BAD_INPUT) {
        Err(err) => fail!("{}", err),
        Ok(interpreter) => interpreter,
    };
    println!("> OK");
}

GDB backtrace:

Decoding GOOD_INPUT...
> OK
Decoding BAD_INPUT...

Program received signal SIGSEGV, Segmentation fault.
0x0000000000404696 in json::decode::h14338055721627637230 ()
(gdb) backtrace
#0  0x0000000000404696 in json::decode::h14338055721627637230 ()
#1  0x0000000000403a38 in main::ha45ff07edb6cb131oca ()
#2  0x00000000004416a3 in start::closure.$x22closure$x22$LP$8257$RP$ ()
#3  0x000000000046b76c in rust_try ()
#4  0x0000000000468ca7 in unwind::try::h7df958a05de7d0830Ld ()
#5  0x0000000000468a97 in task::Task::run::h7e40d178364b7983WTc ()
#6  0x00000000004414c0 in start::h00c9cf36f68b5235Ype ()
#7  0x00000000004412f9 in lang_start::h69b9bfc9bbd58be9ipe ()
#8  0x00007ffff7415fd0 in __libc_start_main () from /lib64/libc.so.6
#9  0x00000000004037a1 in _start ()

Version:

rustc 0.12.0-pre (3ab170ffc 2014-07-30 13:01:10 +0000)

(It also segfaults in the playpen)

cc @erickt

[sfackler]

Could be #15763

[luqmana]

Yep, closing as dupe of #15763.