Infinite recursion in bindgen::ir::ty::Type::safe_canonical_type

Input C++ Header and Bindgen Invocation

It's... complicated. If you have Bazel installed, then check out the rust branch of https://github.com/jonhoo/ray/. The header file being compiled is rust/sys/wrapper.h, though it has transitive includes that go deep into the dependency graph of ray. The best way I know of to get those dependencies is by running

bazel build -s //rust:ray_sys_bindgen

Killing that once it says

[X / Y] Executing genrule //rust:ray_sys_bindgen

Then look for

(cd <long-path-prefix>/execroot/com_github_ray_project_ray && \

Change into that directory manually, and then run:

$ bindgen rust/sys/wrapper.h -o bazel-out/k8-opt/bin/rust/sys/src/lib.rs --enable-cxx-namespaces -- --std=c++17 -x c++ -Isrc/ -Iexternal/plasma/cpp/src/ -Iexternal/boost/ -Iexternal/com_github_grpc_grpc/include/ -Iexternal/com_github_google_flatbuffers/include/ -Iexternal/com_google_absl/ -Iexternal/boringssl/src/third_party/googletest/include/ -Iexternal/com_google_protobuf/src/ -Ibazel-out/k8-opt/bin/src/ -Ibazel-o
ut/k8-opt/bin/ -Isrc/ray/thirdparty/ae/

Actual Results

Bindgen takes forever to run. With --time-passes, I see:

  time:   908.100 ms.   parse
  time:   210.326 ms.   resolve_typerefs
  time:     1.565 ms.   compute_bitfield_units
  time:     0.000 ms.   process_replacements
  time:     5.361 ms.   deanonymize_fields
  time:   478.479 ms.   compute_whitelisted_and_codegen_items
  time:    84.449 ms.   compute_has_vtable
  time:   262.273 ms.   compute_sizedness
  time:    88.773 ms.   compute_has_destructor
  time:   353.122 ms.   find_used_template_parameters

The process is at 100% CPU load on a single core, but produces no further output for a long time. At the time of writing, I have waited for 10 minutes with no progress. Profiling shows basically all time spent in bindgen::ir::ty::Type::canonical_type, called from this stack:

#3  bindgen::ir::ty::Type::safe_canonical_type (self=<optimized out>, ctx=0x7ffc16e7c640) at src/ir/ty.rs:366
#4  bindgen::ir::ty::Type::canonical_type (self=<optimized out>, ctx=0x7ffc16e7c640) at src/ir/ty.rs:330
#5  0x000055f97f48d07a in bindgen::ir::analysis::derive::CannotDerive::constrain_type (self=0x7ffc16e7c250, item=0x7f544f9298f8, ty=<optimized out>) at src/ir/analysis/derive.rs:211
#6  <bindgen::ir::analysis::derive::CannotDerive as bindgen::ir::analysis::MonotoneFramework>::constrain (self=0x7ffc16e7c250, id=...) at src/ir/analysis/derive.rs:660
#7  0x000055f97f483df6 in bindgen::ir::analysis::analyze (extra=...) at src/ir/analysis/mod.rs:166
#8  0x000055f97f427c97 in bindgen::ir::context::BindgenContext::compute_cannot_derive_debug (self=0x7ffc16e7c640) at src/ir/context.rs:2438
#9  0x000055f97f3fee6e in bindgen::ir::context::BindgenContext::gen (self=..., cb=...) at src/ir/context.rs:1198
#10 0x000055f97f3d68ff in bindgen::codegen::codegen (context=...) at src/codegen/mod.rs:3744
#11 bindgen::Bindings::generate (options=...) at src/lib.rs:2052
#12 bindgen::Builder::generate (self=...) at src/lib.rs:1375
#13 0x000055f97f35c4ec in bindgen::main::{{closure}} () at src/main.rs:53
#14 std::panicking::try::do_call (data=0x7ffc16e811b0 "\b\000") at /rustc/5242afe811c2648baf158eee28143c9facc350ee/src/libstd/panicking.rs:292
#15 0x000055f97f58596a in __rust_maybe_catch_panic () at src/libpanic_unwind/lib.rs:80
#16 0x000055f97f356991 in std::panicking::try (f=...) at /rustc/5242afe811c2648baf158eee28143c9facc350ee/src/libstd/panicking.rs:271
#17 std::panic::catch_unwind (f=...) at /rustc/5242afe811c2648baf158eee28143c9facc350ee/src/libstd/panic.rs:394
#18 bindgen::main () at src/main.rs:52

Expected Results

This should complete faster?

Reproduce the issue with the Bazel-generated bindgen command and the supplied C++ header and include paths. Start in src/ir/ty.rs at safe_canonical_type and canonical_type, then follow their callers in src/ir/analysis/derive.rs and src/ir/context.rs. Done means the invocation no longer spends indefinitely in canonical_type and completes in a reasonable time.