A command with a heredoc after a herestring will panic with an array out of bounds variable.

Created by: chrisvittal

Reproduction: cat <<< hello <<EOF Expected behavior: the ability to enter a heredoc followed by printing something, either "hello" or the heredoc or both.

Actual behavior: ion panics and crashes

Build information:

$ ion --version
ion 1.0.5 (x86_64-unknown-linux-gnu)
rev e4952a2151d51a273faca8febf63395e32e30874
$ rustc -V
rustc 1.22.0-nightly (a47c9f870 2017-10-11)

Misc: Backtrace

cdv:~/src/ion# cat <<< hello <<EOF
thread 'main' panicked at 'slice index starts at 1 but ends at 0', /checkout/src/libcore/slice/mod.rs:752:4
stack backtrace:
   0: std::sys::imp::backtrace::tracing::imp::unwind_backtrace
             at /checkout/src/libstd/sys/unix/backtrace/tracing/gcc_s.rs:49
   1: std::sys_common::backtrace::_print
             at /checkout/src/libstd/sys_common/backtrace.rs:69
   2: std::panicking::default_hook::{{closure}}
             at /checkout/src/libstd/sys_common/backtrace.rs:58
             at /checkout/src/libstd/panicking.rs:381
   3: std::panicking::default_hook
             at /checkout/src/libstd/panicking.rs:397
   4: std::panicking::rust_panic_with_hook
             at /checkout/src/libstd/panicking.rs:577
   5: std::panicking::begin_panic
             at /checkout/src/libstd/panicking.rs:538
   6: std::panicking::begin_panic_fmt
             at /checkout/src/libstd/panicking.rs:522
   7: rust_begin_unwind
             at /checkout/src/libstd/panicking.rs:498
   8: core::panicking::panic_fmt
             at /checkout/src/libcore/panicking.rs:71
   9: core::slice::slice_index_order_fail
             at /checkout/src/libcore/slice/mod.rs:752
  10: <core::ops::range::Range<usize> as core::slice::SliceIndex<[T]>>::index
             at /checkout/src/libcore/slice/mod.rs:875
  11: core::slice::<impl core::ops::index::Index<I> for [T]>::index
             at /checkout/src/libcore/slice/mod.rs:728
  12: <alloc::vec::Vec<T> as core::ops::index::Index<core::ops::range::Range<usize>>>::index
             at /checkout/src/liballoc/vec.rs:1572
  13: ion::parser::pipelines::collector::Collector::parse
             at src/parser/pipelines/collector.rs:336
  14: ion::parser::pipelines::collector::Collector::run
             at src/parser/pipelines/collector.rs:23
  15: ion::parser::statement::parse::collect
             at src/parser/statement/parse.rs:11
  16: ion::parser::statement::parse::parse
             at src/parser/statement/parse.rs:167
  17: ion::parser::statement::parse_and_validate
             at src/parser/statement/mod.rs:13
  18: core::ops::function::FnMut::call_mut
             at /checkout/src/libcore/ops/function.rs:146
  19: core::ops::function::impls::<impl core::ops::function::FnOnce<A> for &'a mut F>::call_once
             at /checkout/src/libcore/ops/function.rs:271
  20: <core::option::Option<T>>::map
             at /checkout/src/libcore/option.rs:398
  21: <core::iter::Map<I, F> as core::iter::iterator::Iterator>::next
             at /checkout/src/libcore/iter/mod.rs:1123
  22: <ion::shell::Shell<'a> as ion::shell::flow::FlowLogic>::on_command
             at src/shell/flow.rs:73
  23: <ion::shell::Shell<'a> as ion::shell::binary::Binary>::execute_interactive
             at src/shell/binary.rs:328
  24: <ion::shell::Shell<'a> as ion::shell::binary::Binary>::main
             at src/shell/binary.rs:391
  25: ion::main
             at src/main.rs:76
  26: __rust_maybe_catch_panic
             at /checkout/src/libpanic_unwind/lib.rs:99
  27: std::rt::lang_start
             at /checkout/src/libstd/panicking.rs:459
             at /checkout/src/libstd/panic.rs:361
             at /checkout/src/libstd/rt.rs:59
  28: main
  29: __libc_start_main
  30: _start