Infinite recursion in librustc::metadata::decoder

[SimonSapin]

I’m working on a patch for Servo (commit c12c7a6) that only adds a bunch of code in its "script" crate. Servo before my patch builds fine. The same code in its own crate builds fine. The script crate itself with my code added builds fine. It’s only Servo’s "main" crate, which links against "script", that sends rust in an infinite loop.

gdb shows the stack trace below, except it goes to 3000 or so frames after a few minutes, and growing.

Rust version: rustc 0.8-pre (72b50e7 2013-08-16 01:56:16 -0700)
Colorized stack trace: http://pastebin.com/Tg7APRi2

#0  0x00007fc049d5095b in hashmap::__extensions__::bucket_for_key_with_hash_50288::anon::expr_fn_50301 ()
   from lib/librustc-d3cb8c2ccd84a7a7-0.8-pre.so
#1  0x00007fc049d5055f in hashmap::__extensions__::bucket_sequence_50290::_f480b8be39c3ec7::_0$x2e8$x2dpre ()
   from lib/librustc-d3cb8c2ccd84a7a7-0.8-pre.so
#2  0x00007fc049d5049b in hashmap::__extensions__::bucket_for_key_with_hash_50288::_1fab551126e8674a::_0$x2e8$x2dpre ()
   from lib/librustc-d3cb8c2ccd84a7a7-0.8-pre.so
#3  0x00007fc049d503eb in hashmap::__extensions__::bucket_for_key_50286::_e8c863cbc639f::_0$x2e8$x2dpre ()
   from lib/librustc-d3cb8c2ccd84a7a7-0.8-pre.so
#4  0x00007fc049d502f9 in hashmap::__extensions__::find_50283::_ebf445d0cf0c6b1::_0$x2e8$x2dpre ()
   from lib/librustc-d3cb8c2ccd84a7a7-0.8-pre.so
#5  0x00007fc049d4e089 in middle::resolve::__extensions__::meth_50280::add_child::_9bc551b669fa7eeb::_0$x2e8$x2dpre ()
   from lib/librustc-d3cb8c2ccd84a7a7-0.8-pre.so
#6  0x00007fc049d634af in middle::resolve::__extensions__::build_reduced_graph_for_external_crate::anon::expr_fn_50939 ()
   from lib/librustc-d3cb8c2ccd84a7a7-0.8-pre.so
#7  0x00007fc04a527ae8 in metadata::decoder::__extensions__::meth_92212::process_item_and_pop_name::_ed3a72451bee9133::_0$x2e8$x2dpre ()
   from lib/librustc-d3cb8c2ccd84a7a7-0.8-pre.so
#8  0x00007fc04a528da9 in metadata::decoder::__extensions__::each_child_of_module_or_crate::anon::expr_fn_92220 ()
   from lib/librustc-d3cb8c2ccd84a7a7-0.8-pre.so
#9  0x00007fc04b07512a in ebml::reader::tagged_docs::_669199c64346a9a7::_0$x2e8$x2dpre ()
   from lib/libextra-a7c050cfd46b2c9a-0.8-pre.so
#10 0x00007fc04a52843f in metadata::decoder::__extensions__::meth_92217::each_child_of_module_or_crate::_10e45c12b3c2e244::_0$x2e8$x2dpre ()
   from lib/librustc-d3cb8c2ccd84a7a7-0.8-pre.so
#11 0x00007fc04a5282e2 in metadata::decoder::__extensions__::meth_92215::each_item_of_module::_182d9722d1c9f691::_0$x2e8$x2dpre ()
   from lib/librustc-d3cb8c2ccd84a7a7-0.8-pre.so
#12 0x00007fc04a527c4d in metadata::decoder::__extensions__::meth_92212::process_item_and_pop_name::_ed3a72451bee9133::_0$x2e8$x2dpre ()
   from lib/librustc-d3cb8c2ccd84a7a7-0.8-pre.so
#13 0x00007fc04a528da9 in metadata::decoder::__extensions__::each_child_of_module_or_crate::anon::expr_fn_92220 ()
   from lib/librustc-d3cb8c2ccd84a7a7-0.8-pre.so
#14 0x00007fc04b07512a in ebml::reader::tagged_docs::_669199c64346a9a7::_0$x2e8$x2dpre ()
   from lib/libextra-a7c050cfd46b2c9a-0.8-pre.so
#15 0x00007fc04a52843f in metadata::decoder::__extensions__::meth_92217::each_child_of_module_or_crate::_10e45c12b3c2e244::_0$x2e8$x2dpre ()
   from lib/librustc-d3cb8c2ccd84a7a7-0.8-pre.so
#16 0x00007fc04a5282e2 in metadata::decoder::__extensions__::meth_92215::each_item_of_module::_182d9722d1c9f691::_0$x2e8$x2dpre ()
   from lib/librustc-d3cb8c2ccd84a7a7-0.8-pre.so
#17 0x00007fc04a527c4d in metadata::decoder::__extensions__::meth_92212::process_item_and_pop_name::_ed3a72451bee9133::_0$x2e8$x2dpre ()
   from lib/librustc-d3cb8c2ccd84a7a7-0.8-pre.so
#18 0x00007fc04a5295f8 in metadata::decoder::__extensions__::each_child_of_module_or_crate::anon::expr_fn_92222 ()
   from lib/librustc-d3cb8c2ccd84a7a7-0.8-pre.so

[metajack]

@pcwalton this looks like your domain. This is blocking the style system unless we can find a workaround. Ideas?

[pcwalton]

each_path problem? I removed that method recently. Try upgrading Rust.

[SimonSapin]

I still have the same issue on rustc 0.8-pre (c822d10 2013-08-27 11:35:51 -0700). The stack trace looks very similar

#0  0x00007ff33c973ab8 in str::__extensions__::meth_53755::next::_a327b7413cb432e1::_0$x2e8$x2dpre ()
   from lib/librustc-d3cb8c2ccd84a7a7-0.8-pre.so
#1  0x00007ff33c97383d in str::__extensions__::meth_53749::next::_236ae8d43b4b690::_0$x2e8$x2dpre ()
   from lib/librustc-d3cb8c2ccd84a7a7-0.8-pre.so
#2  0x00007ff33c972fa5 in vec::__extensions__::from_iterator_53719::_63c065d1b2675735::_0$x2e8$x2dpre ()
   from lib/librustc-d3cb8c2ccd84a7a7-0.8-pre.so
#3  0x00007ff33c972ea6 in iterator::Iterator::collect_53716::_70c43414f099a697::_0$x2e8$x2dpre ()
   from lib/librustc-d3cb8c2ccd84a7a7-0.8-pre.so
#4  0x00007ff33c96fb5d in middle::resolve::__extensions__::build_reduced_graph_for_external_crate::anon::expr_fn_53714 ()
   from lib/librustc-d3cb8c2ccd84a7a7-0.8-pre.so
#5  0x00007ff33d2a2640 in metadata::decoder::__extensions__::meth_94926::process_item_and_pop_name::_98bc6c9258a918de::_0$x2e8$x2dpre ()
   from lib/librustc-d3cb8c2ccd84a7a7-0.8-pre.so
#6  0x00007ff33d2a443a in metadata::decoder::__extensions__::each_child_of_module_or_crate::anon::expr_fn_94936 ()
   from lib/librustc-d3cb8c2ccd84a7a7-0.8-pre.so
#7  0x00007ff33dec0aee in ebml::reader::tagged_docs::_54b95af320ce4fde::_0$x2e8$x2dpre ()
   from lib/libextra-a7c050cfd46b2c9a-0.8-pre.so
#8  0x00007ff33d29630c in metadata::decoder::each_reexport::_38ad7c4b4254dae::_0$x2e8$x2dpre ()
   from lib/librustc-d3cb8c2ccd84a7a7-0.8-pre.so
#9  0x00007ff33d2a319d in metadata::decoder::__extensions__::meth_94931::each_child_of_module_or_crate::_7411f6a824c25f::_0$x2e8$x2dpre ()
   from lib/librustc-d3cb8c2ccd84a7a7-0.8-pre.so
#10 0x00007ff33d2a2f1e in metadata::decoder::__extensions__::meth_94929::each_item_of_module::_182d9722d1c9f691::_0$x2e8$x2dpre ()
   from lib/librustc-d3cb8c2ccd84a7a7-0.8-pre.so
#11 0x00007ff33d2a27b2 in metadata::decoder::__extensions__::meth_94926::process_item_and_pop_name::_98bc6c9258a918de::_0$x2e8$x2dpre ()
   from lib/librustc-d3cb8c2ccd84a7a7-0.8-pre.so
#12 0x00007ff33d2a443a in metadata::decoder::__extensions__::each_child_of_module_or_crate::anon::expr_fn_94936 ()
   from lib/librustc-d3cb8c2ccd84a7a7-0.8-pre.so
#13 0x00007ff33dec0aee in ebml::reader::tagged_docs::_54b95af320ce4fde::_0$x2e8$x2dpre ()
   from lib/libextra-a7c050cfd46b2c9a-0.8-pre.so
#14 0x00007ff33d29630c in metadata::decoder::each_reexport::_38ad7c4b4254dae::_0$x2e8$x2dpre ()
   from lib/librustc-d3cb8c2ccd84a7a7-0.8-pre.so
#15 0x00007ff33d2a319d in metadata::decoder::__extensions__::meth_94931::each_child_of_module_or_crate::_7411f6a824c25f::_0$x2e8$x2dpre ()
   from lib/librustc-d3cb8c2ccd84a7a7-0.8-pre.so
#16 0x00007ff33d2a2f1e in metadata::decoder::__extensions__::meth_94929::each_item_of_module::_182d9722d1c9f691::_0$x2e8$x2dpre ()
   from lib/librustc-d3cb8c2ccd84a7a7-0.8-pre.so
#17 0x00007ff33d2a27b2 in metadata::decoder::__extensions__::meth_94926::process_item_and_pop_name::_98bc6c9258a918de::_0$x2e8$x2dpre ()
   from lib/librustc-d3cb8c2ccd84a7a7-0.8-pre.so

[SimonSapin]

@pcwalton did you make your changes more recently than that?

[metajack]

@pcwalton It looks like your patch didn't land? #8657

[SimonSapin]

And I actually don’t see each_path in either stack trace.

[SimonSapin]

Upgrading to Rust 0ac3e02 fixed this for me.