pin ocaml

Author: hhugo

.github/workflows/build.yml

@@ -49,7 +49,7 @@ jobs:
             skip-test: false
             skip-doc: true
           - os: ubuntu-latest
-            ocaml-compiler: "5.3"
+            ocaml-compiler: "ocaml-variants.5.3.1+trunk"
             skip-effects: false
             skip-test: false
             skip-doc: false
@@ -111,6 +111,10 @@ jobs:
         with:
           ocaml-compiler: ${{ matrix.ocaml-compiler }}
 
+      - name: patch compiler
+        if: matrix.ocaml-compiler == 'ocaml-variants.5.3.1+trunk'
+        run: opam pin ocaml-variants https://github.com/hhugo/ocaml.git#optimization-hints
+
       # Work-around a race between reinstalling mingw-w64-shims
       # (because of conf-pkg-config optional dep) and installing other
       # packages that implicitly depend on mingw-w64-shims.