Fix semaphore bug in basement

Author: Svetlitski

.github/workflows/build.yml

@@ -68,13 +68,23 @@ jobs:
 
           export OPAMYES=1
           export OPAMJOBS=$(($(nproc) + 2))
-          export CC=musl-gcc
           echo "OPAMYES=1" >> "$GITHUB_ENV"
           echo "OPAMJOBS=$OPAMJOBS" >> "$GITHUB_ENV"
 
           opam init --bare -yav https://github.com/ocaml/opam-repository.git
           opam switch set ${{ matrix.ocaml-version }} 2>/dev/null || \
             opam switch create ${{ matrix.ocaml-version }} --repos ox=git+https://github.com/oxcaml/opam-repository.git,default
+
+      - name: Vendor Basement
+        run: |
+          mkdir ../basement
+          curl -L 'https://github.com/janestreet/basement/archive/c657898128a97dcdfbe4b25d79fd0de2e1e5218f.tar.gz' | \
+            tar -C ../basement -xz --strip-components=1
+          git -C ../basement apply $PWD/vendor/basement-semaphore-bug-fix.patch
+          opam pin basement ../basement
+
+      - name: Vendor Core_unix
+        run: |
           mkdir ../core_unix
           curl -L 'https://github.com/janestreet/core_unix/archive/63390a3f75376156e77ed49d6cc07ca48a90dd53.tar.gz' | \
             tar -C ../core_unix -xz --strip-components=1

vendor/basement-semaphore-bug-fix.patch

@@ -0,0 +1,19 @@
+commit 16d35743d6b52bc0b38702a459025ba82bd8811f
+Author: Fake Name <fake@gmail.com>
+Date:   Thu Dec 11 03:26:20 2025 +0000
+
+    Fix bug where `sem_close` was being called on an unnamed semaphore
+
+diff --git a/src/blocking_mutex.h b/src/blocking_mutex.h
+index b1d01df..c4658e3 100644
+--- a/src/blocking_mutex.h
++++ b/src/blocking_mutex.h
+@@ -106,7 +106,7 @@ Caml_inline int blocking_mutex_destroy(blocking_mutex mut) {
+   caml_stat_free(mut);
+   return MUTEX_SUCCESS;
+ #else
+-  if (sem_close(&mut->sem) == MUTEX_SUCCESS) {
++  if (sem_destroy(&mut->sem) == MUTEX_SUCCESS) {
+     caml_stat_free(mut);
+     return MUTEX_SUCCESS;
+   }