add github workflow for test-pypi cross-OS wheel builds

Author: AlePalu

.github/workflows/testpypi-linux.yml

@@ -0,0 +1,53 @@
+name: Build Linux ABI3 wheels (TestPyPI)
+
+on:
+  push:
+    tags:
+      - "v*-test*"   # only run on tags for experimental versions
+
+jobs:
+  build_wheels:
+    name: Build linux wheels
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v6
+        with:
+          persist-credentials: false
+          submodules: recursive
+
+      # enable QEMU emulation to build for arm64 on x86_64 runner
+      - name: Set up QEMU
+        if: runner.os == 'Linux'
+        uses: docker/setup-qemu-action@v3
+        with:
+          platforms: all
+
+      # used to host cibuildwheel
+      - uses: actions/setup-python@v6
+
+      # install build depdencies
+      - name: Install build tools
+        run: python -m pip install setuptools wheel cibuildwheel build twine nanobind
+
+      - name: Download Eigen headers
+        run: |
+          mkdir -p deps
+          mkdir -p deps/eigen3
+          curl -L https://gitlab.com/libeigen/eigen/-/archive/5.0.0/eigen-5.0.0.tar.gz \
+            | tar xz -C deps/eigen3 --strip-components=1
+
+      - name: Build wheels
+        run: python -m cibuildwheel --output-dir wheelhouse
+        env:
+          CIBW_BUILD: "cp311-* cp312-* cp313-* cp314-*"
+          CIBW_ARCHS_MACOS: "x86_64 arm64"
+
+      - name: Upload to TestPyPI
+        run: |
+          twine upload \
+            --repository-url https://test.pypi.org/legacy/ \
+            wheelhouse/*
+        env:
+          TWINE_USERNAME: __token__
+          TWINE_PASSWORD: ${{ secrets.TEST_PYPI_TOKEN }}

.github/workflows/testpypi-macos.yml

@@ -0,0 +1,56 @@
+name: Build and upload wheels to TestPyPI
+
+on:
+  push:
+    tags:
+      - "v*-test*"   # only run on tags for experimental versions
+
+jobs:
+  build_wheels:
+    name: Build macos wheels
+    runs-on: macos-26
+
+    steps:
+      - uses: actions/checkout@v6
+        with:
+          persist-credentials: false
+          submodules: recursive
+
+      # enable QEMU emulation to build for arm64 on x86_64 runner
+      - name: Set up QEMU
+        if: runner.os == 'Linux'
+        uses: docker/setup-qemu-action@v3
+        with:
+          platforms: all
+
+      # used to host cibuildwheel
+      - uses: actions/setup-python@v6
+
+      # install build depdencies
+      - name: Install build tools
+        run: python -m pip install setuptools wheel cibuildwheel build twine nanobind
+
+      - name: Download Eigen headers
+        run: |
+          mkdir -p deps
+          mkdir -p deps/eigen3
+          curl -L https://gitlab.com/libeigen/eigen/-/archive/5.0.0/eigen-5.0.0.tar.gz \
+            | tar xz -C deps/eigen3 --strip-components=1
+
+      - name: Build wheels
+        run: |
+          python -m cibuildwheel --output-dir wheelhouse
+        env:
+          CIBW_BUILD: "cp311-* cp312-* cp313-* cp314-*"
+          CIBW_ENVIRONMENT: >
+            CC=$(brew --prefix llvm@20)/bin/clang
+            CXX=$(brew --prefix llvm@20)/bin/clang++
+
+      - name: Upload to TestPyPI
+        run: |
+          twine upload \
+            --repository-url https://test.pypi.org/legacy/ \
+            wheelhouse/*
+        env:
+          TWINE_USERNAME: __token__
+          TWINE_PASSWORD: ${{ secrets.TEST_PYPI_TOKEN }}

.github/workflows/testpypi-windows.yml

@@ -22,21 +22,12 @@
 namespace fdapde {
 namespace internals {
 
-template <typename IndexSeq> struct Applier;
-
-template <int... Ns> struct Applier<std::integer_sequence<int, Ns...>> {
-    template <typename F> static constexpr decltype(auto) call(F&& f) {
-        // We use the pack here, inside the body, which is safer
-        return std::forward<F>(f).template operator()<Ns...>();
-    }
-};
-
-template <int N, typename F> constexpr decltype(auto) apply_index_pack(F&& f) {
-    using Seq = std::make_integer_sequence<int, N>;
-    return internals::Applier<Seq>::call(std::forward<F>(f));
+// apply lambda F_ to each value in index pack {0, ..., N_ - 1}
+template <int N_, typename F_> constexpr decltype(auto) apply_index_pack(F_&& f) {
+    return [&]<int... Ns_>(std::integer_sequence<int, Ns_...>) -> decltype(auto) {
+        return f.template operator()<Ns_...>();
+    }(std::make_integer_sequence<int, N_> {});
 }
-  
-
 template <int N_, typename F_> constexpr void for_each_index_in_pack(F_&& f) {
     [&]<int... Ns_>(std::integer_sequence<int, Ns_...>) {
         (f.template operator()<Ns_>(), ...);

include/fdaPDE-cpp/fdaPDE/core/fdaPDE/src/utility/meta.h

@@ -8,7 +8,7 @@ build-backend = "scikit_build_core.build"
 
 [project]
 name = "fdaPDE"
-version = "2.0.0rc3"
+version = "2.0.0rc4"
 description="The python wrapper to the fdaPDE library for physics-informed spatial and functional data analysis."
 readme = "README.md"
 dependencies = ["numpy", "matplotlib"]