Codegen fails when case default clause returns unboxed value

[timmw]

Issue Description

Either of these cause an error:

(case :any 
  :any :any 
  (nil? :any))

(case :any 
  :any :any 
  #cpp true)

Error: no viable conversion from returned value of type 'bool' to function return type 'jank::runtime::object_ref' (aka 'oref')

Full error

user=> (case :any :any :any (nil? :any))
In file included from <<< inputs >>>:1:
/home/tim/src/third-party/jank/compiler+runtime/src/jank/clojure/core.jank:3965:8: error: no viable conversion from returned value of type 'bool' to function return type 'jank::runtime::object_ref' (aka 'oref<object>')
 3965 | return v21;
      |        ^~~
/home/tim/src/third-party/jank/compiler+runtime/include/cpp/jank/runtime/oref.hpp:235:5: note: candidate constructor not viable: no known conversion from 'bool' to 'void *const' for 1st argument; take the address of the argument with &
  235 |     oref(void * const data) noexcept
      |     ^    ~~~~~~~~~~~~~~~~~
/home/tim/src/third-party/jank/compiler+runtime/include/cpp/jank/runtime/oref.hpp:214:5: note: candidate constructor not viable: no known conversion from 'bool' to 'const oref<jank::runtime::object> &' for 1st argument
  214 |     oref(oref const &rhs) = default;
      |     ^    ~~~~~~~~~~~~~~~
/home/tim/src/third-party/jank/compiler+runtime/include/cpp/jank/runtime/oref.hpp:215:5: note: candidate constructor not viable: no known conversion from 'bool' to 'oref<jank::runtime::object> &&' for 1st argument
  215 |     oref(oref &&rhs) noexcept = default;
      |     ^    ~~~~~~~~~~
/home/tim/src/third-party/jank/compiler+runtime/include/cpp/jank/runtime/oref.hpp:217:5: note: candidate constructor not viable: no known conversion from 'bool' to 'nullptr_t' (aka 'std::nullptr_t') for 1st argument
  217 |     oref(nullptr_t) noexcept = delete;
      |     ^    ~~~~~~~~~
/home/tim/src/third-party/jank/compiler+runtime/include/cpp/jank/runtime/oref.hpp:219:5: note: candidate constructor not viable: no known conversion from 'bool' to '_jank_null' for 1st argument
  219 |     oref(_jank_null) noexcept
      |     ^    ~~~~~~~~~~
/home/tim/src/third-party/jank/compiler+runtime/include/cpp/jank/runtime/oref.hpp:224:5: note: candidate constructor not viable: no known conversion from 'bool' to 'value_type *const' (aka 'object *const') for 1st argument
  224 |     oref(value_type * const data) noexcept
      |     ^    ~~~~~~~~~~~~~~~~~~~~~~~
/home/tim/src/third-party/jank/compiler+runtime/include/cpp/jank/runtime/oref.hpp:229:5: note: candidate constructor not viable: no known conversion from 'bool' to 'const value_type *const' (aka 'const object *const') for 1st argument
  229 |     oref(value_type const * const data) noexcept
      |     ^    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/tim/src/third-party/jank/compiler+runtime/include/cpp/jank/runtime/oref.hpp:247:5: note: candidate constructor not viable: no known conversion from 'bool' to 'const detail::untagged_ptr' for 1st argument
  247 |     oref(detail::untagged_ptr const p) noexcept
      |     ^    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/tim/src/third-party/jank/compiler+runtime/include/cpp/jank/runtime/oref.hpp:242:5: note: candidate template ignored: could not match 'T *' against 'bool'
  242 |     oref(T * const typed_data) noexcept
      |     ^
/home/tim/src/third-party/jank/compiler+runtime/include/cpp/jank/runtime/oref.hpp:254:5: note: candidate template ignored: could not match 'const T *' against 'bool'
  254 |     oref(T const * const typed_data) noexcept
      |     ^
/home/tim/src/third-party/jank/compiler+runtime/include/cpp/jank/runtime/oref.hpp:261:5: note: candidate template ignored: could not match 'oref<T>' against 'bool'
  261 |     oref(oref<T> const &typed_data) noexcept
      |     ^
/home/tim/src/third-party/jank/compiler+runtime/include/cpp/jank/runtime/oref.hpp:268:5: note: candidate template ignored: could not match 'oref<T>' against 'bool'
  268 |     oref(oref<T> const &typed_data) noexcept
      |     ^
/home/tim/src/third-party/jank/compiler+runtime/include/cpp/jank/runtime/oref.hpp:275:5: note: candidate template ignored: could not match 'oref<T>' against 'bool'
  275 |     oref(oref<T> const &typed_data) noexcept
      |     ^
error: Parsing failed.
─ internal/codegen-failure ─────────────────────────────────────────────────────────────────────────
error: Unable to compile C++ source.

Reproduction Steps

Run this in repl:

(case :any :any :any (nil? :any))

jank health check

─ system ───────────────────────────────────────────────────────────────────────────────────────────
─ ✅ operating system: linux
─ ✅ default triple: x86_64-unknown-linux-gnu

─ jank install ─────────────────────────────────────────────────────────────────────────────────────
─ ✅ jank version: jank-0.1-alpha
─ ✅ jank cmake build type: Release
─ ✅ jank resource dir: ../lib/jank/0.1 
─ ✅ jank resolved resource dir: /home/tim/.local/bin/../lib/jank/0.1 (found)
─ ✅ jank user cache dir: /home/tim/.cache/jank/x86_64-unknown-linux-gnu-5acfabba52afe16f52b7d453c209b2ba95bbfec5dd9715ff280234af21cc225b (found)

─ clang install ────────────────────────────────────────────────────────────────────────────────────
─ ✅ configured clang path: /nix/store/yjvbvb8rm3pbws3hap8csf62jf9cgvfc-clang-wrapper-23.0.0-unstable-2026-06-21/bin/clang++ (found)
─ ✅ configured clang resource dir: /nix/store/yjvbvb8rm3pbws3hap8csf62jf9cgvfc-clang-wrapper-23.0.0-unstable-2026-06-21/resource-root (found)

─ jank runtime ─────────────────────────────────────────────────────────────────────────────────────
─ ✅ jank runtime initialized
─ ✅ jank pch path: /home/tim/.cache/jank/x86_64-unknown-linux-gnu-5acfabba52afe16f52b7d453c209b2ba95bbfec5dd9715ff280234af21cc225b (found)
─ ✅ jank can jit compile c++
─ ✅ jank can aot compile working binaries

─ support ──────────────────────────────────────────────────────────────────────────────────────────
If you're having issues with jank, please either ask the jank community on the Clojurians Slack or report the issue on Github.

─ Slack: https://clojurians.slack.com/archives/C03SRH97FDK
─ Github: https://github.com/jank-lang/jank

Stack trace

No response

OS Version Information

Fedora 43

I acknowledge that:

• I have searched the jank repository (both open and closed Discussions and Issues) and confirm this is not a duplicate of an existing issue or discussion.
• I have checked the "Preview" tab on all text fields to ensure that everything looks right, and have wrapped all configuration and code in code blocks with a group of three backticks (```) on separate lines.

[jeaye]

Thanks for another excellent report with a minimal repro! I'll get this fixed and tested and I'll report back when it's merged.