ICE during macro expansion: index out of bounds: the len is 5 but the index is 5

[japaric]

STR

use std::io::MemWriter;

fn main() {
    let (foo, bar) = ((), ());
    let ref mut sink = MemWriter::new();
    // OK
    (writeln!(sink, "{} {}", foo, bar)).unwrap();
    // ICE
    (writeln!(sink, "{} {}", foo), bar).unwrap();
    //                             ^~ misplaced the `bar` argument
}

Version

rustc 0.12.0-pre (4067252de 2014-09-07 14:31:24 +0000)

Backtrace

task 'rustc' failed at 'index out of bounds: the len is 5 but the index is 5', /var/tmp/paludis/build/dev-lang-rust-scm/work/rust-scm/src/libsyntax/lib.rs:1

stack backtrace:
   1:     0x7f26c413cde0 - rt::backtrace::imp::write::h23751f5ff57d310aH8q
   2:     0x7f26c413ff80 - <unknown>
   3:     0x7f26c491b610 - unwind::begin_unwind_inner::hc65add009f437d5162d
   4:     0x7f26c491b100 - unwind::begin_unwind_fmt::hf241d83f5d83b087q0d
   5:     0x7f26c491b0c0 - rust_begin_unwind
   6:     0x7f26c495b490 - failure::begin_unwind::hb3e4116c2b1c26d7Wnk
   7:     0x7f26c495b340 - failure::fail_bounds_check::hf4e753cfc0d53aecSkk
   8:     0x7f26c043cd10 - codemap::FileMap::get_line::h1b3e37e16ad1df99pjE
   9:     0x7f26c04468e0 - <unknown>
  10:     0x7f26c0443a40 - diagnostic::EmitterWriter.Emitter::emit::h3aaf2cc69b2a54f8nCF
  11:     0x7f26c0442170 - diagnostic::Handler::emit::he175888aeefb5595ajF
  12:     0x7f26c03bc070 - ext::base::ExtCtxt<'a>::span_err::hdd76f90faf79a373OJ3
  13:     0x7f26c05a3450 - <unknown>
  14:     0x7f26c051f6f0 - ext::format::expand_preparsed_format_args::h7606b70b827955c6K4b
  15:     0x7f26c04d00f0 - ext::format::expand_format_args_method::h6f7281d7e34d1b7aK3b
  16:     0x7f26c04ccf20 - ext::base::BasicMacroExpander.TTMacroExpander::expand::h7c75fe04d027d993lm3
  17:     0x7f26c054bfe0 - <unknown>
  18:     0x7f26c0556680 - <unknown>
  19:     0x7f26c0555020 - ext::expand::MacroExpander<'a, 'b>.Folder::fold_block::h8da21186045129c9uUa
  20:     0x7f26c0551ae0 - <unknown>
  21:     0x7f26c054bfe0 - <unknown>
  22:     0x7f26c04dc510 - ext::expand::MacroExpander<'a, 'b>.Folder::fold_expr::hefc0d51927d8bb7dSSa
  23:     0x7f26c054bfe0 - <unknown>
  24:     0x7f26c04dc510 - ext::expand::MacroExpander<'a, 'b>.Folder::fold_expr::hefc0d51927d8bb7dSSa
  25:     0x7f26c054bfe0 - <unknown>
  26:     0x7f26c04dc510 - ext::expand::MacroExpander<'a, 'b>.Folder::fold_expr::hefc0d51927d8bb7dSSa
  27:     0x7f26c04f29a0 - <unknown>
  28:     0x7f26c0551ae0 - <unknown>
  29:     0x7f26c054bfe0 - <unknown>
  30:     0x7f26c04dc510 - ext::expand::MacroExpander<'a, 'b>.Folder::fold_expr::hefc0d51927d8bb7dSSa
  31:     0x7f26c0553700 - <unknown>
  32:     0x7f26c04f29a0 - <unknown>
  33:     0x7f26c0551ae0 - <unknown>
  34:     0x7f26c054bfe0 - <unknown>
  35:     0x7f26c04dc510 - ext::expand::MacroExpander<'a, 'b>.Folder::fold_expr::hefc0d51927d8bb7dSSa
  36:     0x7f26c05732e0 - <unknown>
  37:     0x7f26c0561bd0 - <unknown>
  38:     0x7f26c05653e0 - ext::expand::MacroExpander<'a, 'b>.Folder::fold_stmt::hd1c3456308c75fdc9Ta
  39:     0x7f26c057a340 - <unknown>
  40:     0x7f26c0556680 - <unknown>
  41:     0x7f26c0555020 - ext::expand::MacroExpander<'a, 'b>.Folder::fold_block::h8da21186045129c9uUa
  42:     0x7f26c0550de0 - <unknown>
  43:     0x7f26c055d270 - ext::expand::MacroExpander<'a, 'b>.Folder::fold_item_underscore::h27f572d5760062f3STa
  44:     0x7f26c055cf30 - <unknown>
  45:     0x7f26c0557130 - <unknown>
  46:     0x7f26c055f9f0 - ext::expand::MacroExpander<'a, 'b>.Folder::fold_item::h2bcc44b49b9c9d1awTa
  47:     0x7f26c055f990 - <unknown>
  48:     0x7f26c04fe200 - <unknown>
  49:     0x7f26c055ef60 - <unknown>
  50:     0x7f26c058e8b0 - ext::expand::expand_crate::hd9a395f29defc8adpWa
  51:     0x7f26c55ed510 - <unknown>
  52:     0x7f26c53e3300 - driver::driver::phase_2_configure_and_expand::h6fe4676a48aa874bdzD
  53:     0x7f26c55af2c0 - driver::driver::compile_input::h86a4be38205dedd4EsD
  54:     0x7f26c5640b60 - <unknown>
  55:     0x7f26c5640a50 - <unknown>
  56:     0x7f26c4d2d350 - <unknown>
  57:     0x7f26c4d2d150 - <unknown>
  58:     0x7f26c60ea4d0 - <unknown>
  59:     0x7f26c4968de0 - <unknown>
  60:     0x7f26c4968dd0 - rust_try
  61:     0x7f26c4918ce0 - unwind::try::h2eddd5244ebec084gRd
  62:     0x7f26c4918b40 - task::Task::run::hf7cea9fec0a760e292c
  63:     0x7f26c60ea240 - <unknown>
  64:     0x7f26c491a6c0 - <unknown>
  65:     0x7f26c3bf8000 - start_thread
  66:     0x7f26c45e9ec9 - clone
  67:                0x0 - <unknown>

[alexcrichton]

Closing as a dupe of #14091