Lean 4 fork for HoTT-compatible kernel extensions (Path types, transport, HITs). Maintained against upstream leanprover/lean4.
db1e2ac34c
This PR fixes runtime build issues when `LEAN_MULTI_THREAD` is not set.
## Problem
When building with `LEAN_MULTI_THREAD` undefined (required for
Emscripten/WASM targets), the stub `unique_lock<T>` in
`src/runtime/thread.h` is missing two members that the real
`std::unique_lock` provides:
1. **`release()`** — called by runtime code paths, causes a compile
error when the stub is active
2. **`unique_lock(T const &, std::adopt_lock_t)`** — required by code
that acquires a lock before constructing the `unique_lock`
The other stubs in this file (`mutex`, `lock_guard`,
`condition_variable`) are complete; only `unique_lock` is missing API
surface.
## Fix
Add the two missing members to the single-threaded `unique_lock` stub:
```cpp
unique_lock(T const &, std::adopt_lock_t) {}
T * release() { return nullptr; }
```
Both are no-ops, matching the semantics of a single-threaded
environment. `release()` returns `nullptr` (no mutex to release). The
`adopt_lock_t` constructor is a no-op (no lock to adopt).
## Evidence
I've been using this fix in a production project
([specify-lean](https://github.com/kjsdesigns/specify)) since v4.27.0 to
build the Lean4 runtime to WASM via Emscripten. The fix has been stable
across multiple Lean version bumps.
I posted about this on
[Zulip](https://leanprover.zulipchat.com/#narrow/channel/270676-lean4/topic/WASM.20build.20fixes.3A.20libuv.20symbol.20leakage.20.28.236817.29.20and.20unique_lo/with/580836892)
on 2026-03-21.
Co-authored-by: Keith Seim <keith@MacBook-Pro.local>
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| RELEASES.md | ||
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