updating nanobind to 2.2 allows simplifying type_caster<SeqId::OptionalNum>

and nanobind is compatible with Clang 8 again

Author: wojdyr

.github/workflows/ci.yml

@@ -181,18 +181,18 @@ jobs:
     - name: run tests under valgrind
       run: PYTHONMALLOC=malloc valgrind python3 -m unittest discover -v -s tests/
 
-  ubuntu2004_clang9:
-    name: "Ubuntu 20.04 with Clang 9"
+  ubuntu2004_clang8:
+    name: "Ubuntu 20.04 with Clang 8"
     runs-on: ubuntu-20.04
     if: "!contains(github.event.head_commit.message, '[skip ci]')"
     env:
-      CC: clang-9
-      CXX: clang++-9
+      CC: clang-8
+      CXX: clang++-8
       SKBUILD_CMAKE_ARGS: "-DCMAKE_CXX_STANDARD=11;-DEXTRA_WARNINGS=ON;-DSTANDALONE_PYTHON_MODULE=OFF"
       SKBUILD_CMAKE_TARGETS: "all;check"
     steps:
     - uses: actions/checkout@v4
-    - run: sudo apt-get install clang-9 libz-dev python3-pip python3-numpy
+    - run: sudo apt-get install clang-8 libz-dev python3-pip python3-numpy
     - name: install nanobind
       run: |
         sudo /usr/bin/python3 -m pip install nanobind build

pyproject.toml

@@ -1,7 +1,7 @@
 [build-system]
 requires = [
     "scikit-build-core ~=0.10.7",
-    "nanobind >=2.1",
+    "nanobind >=2.2",
     "typing-extensions >=4.0; python_version < '3.11'"
 ]
 build-backend = "scikit_build_core.build"

python/meta.h

@@ -1,31 +1,12 @@
+#include <nanobind/stl/detail/nb_optional.h>
 
 namespace gemmi {
   std::ostream& operator<< (std::ostream& os, const Entity& ent);
 }
 
 namespace nanobind { namespace detail {
-  template<> struct type_caster<gemmi::SeqId::OptionalNum> {
-    NB_TYPE_CASTER(gemmi::SeqId::OptionalNum, optional_name(const_name("int")))
-    using Caster =  make_caster<int>;
-
-    bool from_python(handle src, uint8_t flags, cleanup_list* cleanup) noexcept {
-      if (src.is_none()) {
-        value = Value();
-        return true;
-      }
-      Caster caster;
-      if (!caster.from_python(src, flags_for_local_caster<int>(flags), cleanup))
-        return false;
-      value = caster.operator cast_t<int>();
-      return true;
-    }
-
-    static handle from_cpp(Value value, rv_policy policy, cleanup_list *cleanup) noexcept {
-      if (!value)
-        return none().release();
-      return Caster::from_cpp(*value, policy, cleanup);
-    }
-  };
+  template<> struct type_caster<gemmi::SeqId::OptionalNum>
+    : optional_caster<gemmi::SeqId::OptionalNum> {};
 }} // namespace nanobind::detail
 
 NB_MAKE_OPAQUE(std::vector<gemmi::Helix>)