Fix building and running on pre-2026 MKL versions

.github/workflows/conda-package-cf.yml

@@ -108,6 +108,14 @@ jobs:
           channels: conda-forge
           python-version: ${{ matrix.python }}
 
+      - name: Update conda
+        run: |
+          conda update -n base --all
+
+      - name: Install conda build
+        run: |
+          conda install -n base -y conda-build
+
       - name: Cache conda packages
         uses: actions/cache@27d5ce7f107fe9357f9df03efb73ab90386fccae # v5.0.5
         env:
@@ -126,9 +134,12 @@ jobs:
           echo "CONDA_BLD=$CONDA\\conda-bld\\win-64\\" >> "$GITHUB_ENV"
           echo "WHEELS_OUTPUT_FOLDER=$GITHUB_WORKSPACE\\" >> "$GITHUB_ENV"
 
-      - name: Install conda build
+      - name: Show Conda info
+        run: |
+          conda info --all
+
+      - name: List base environment packages
         run: |
-          conda install -n base -y conda-build
           conda list -n base
 
       - name: Build conda package
@@ -301,3 +312,153 @@ jobs:
         run: |
           conda activate ${{ env.TEST_ENV_NAME }}
           pytest -v --pyargs ${{ env.MODULE_NAME }}
+
+  build_osx:
+    runs-on: macos-26-intel
+
+    strategy:
+      matrix:
+        python: ['3.10', '3.11', '3.12', '3.13', '3.14']
+
+    steps:
+      - name: Cancel Previous Runs
+        uses: styfle/cancel-workflow-action@d07a454dad7609a92316b57b23c9ccfd4f59af66 # 0.13.1
+        with:
+          access_token: ${{ github.token }}
+
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+        with:
+          fetch-depth: 0
+
+      - uses: conda-incubator/setup-miniconda@8ee1f361103df19b6f8c8655fd3967a8ecb162d5 # v4.0.1
+        with:
+          miniforge-version: latest
+          activate-environment: build
+          channels: conda-forge
+          python-version: ${{ matrix.python }}
+
+      - name: Cache conda packages
+        uses: actions/cache@27d5ce7f107fe9357f9df03efb73ab90386fccae # v5.0.5
+        env:
+          CACHE_NUMBER: 0  # Increase to reset cache
+        with:
+          path: /Users/runner/conda_pkgs_dir
+          key:
+            ${{ runner.os }}-conda-${{ env.CACHE_NUMBER }}-python-${{ matrix.python }}-${{hashFiles('**/meta.yaml') }}
+          restore-keys: |
+            ${{ runner.os }}-conda-${{ env.CACHE_NUMBER }}-python-${{ matrix.python }}-
+            ${{ runner.os }}-conda-${{ env.CACHE_NUMBER }}-
+
+      - name: Install conda-build
+        shell: bash -el {0}
+        run: |
+          conda install -n base -y conda-build
+          conda list -n base
+
+      - name: Store conda paths as envs
+        shell: bash -el {0}
+        run: |
+          echo "CONDA_BLD=$CONDA/conda-bld/osx-64/" >> "$GITHUB_ENV"
+          echo "WHEELS_OUTPUT_FOLDER=$GITHUB_WORKSPACE/" >> "$GITHUB_ENV"
+
+      - name: Build conda package
+        shell: bash -el {0}
+        run: |
+          CHANNELS=(-c conda-forge -c conda-forge/label/python_rc --override-channels)
+          VERSIONS=(--python "${{ matrix.python }}")
+          TEST=(--no-test)
+
+          conda build \
+            "${TEST[@]}" \
+            "${VERSIONS[@]}" \
+            "${CHANNELS[@]}" \
+            conda-recipe-cf
+
+      - name: Upload artifact
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
+        with:
+          name: ${{ env.PACKAGE_NAME }} ${{ runner.os }} Python ${{ matrix.python }}
+          path: ${{ env.CONDA_BLD }}${{ env.PACKAGE_NAME }}-*.conda
+
+      - name: Upload wheels artifact
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
+        with:
+          name: ${{ env.PACKAGE_NAME }} ${{ runner.os }} Wheels Python ${{ matrix.python }}
+          path: ${{ env.WHEELS_OUTPUT_FOLDER }}mkl_service-*.whl
+
+  test_osx:
+    needs: build_osx
+    runs-on: ${{ matrix.runner }}
+
+    strategy:
+      matrix:
+        python: ['3.10', '3.11', '3.12', '3.13', '3.14']
+        experimental: [false]
+        runner: [macos-26-intel]
+    continue-on-error: ${{ matrix.experimental }}
+    env:
+      CHANNELS: -c conda-forge -c conda-forge/label/python_rc --override-channels
+
+    steps:
+      - name: Download artifact
+        uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8.0.1
+        with:
+          name: ${{ env.PACKAGE_NAME }} ${{ runner.os }} Python ${{ matrix.python }}
+
+      - uses: conda-incubator/setup-miniconda@8ee1f361103df19b6f8c8655fd3967a8ecb162d5 # v4.0.1
+        with:
+          miniforge-version: latest
+          channels: conda-forge
+          activate-environment: base
+
+      - name: Install conda-index
+        shell: bash -el {0}
+        run: conda install -n base -y conda-index
+
+      - name: Create conda channel
+        shell: bash -el {0}
+        run: |
+          mkdir -p "$GITHUB_WORKSPACE/channel/osx-64"
+          conda index "$GITHUB_WORKSPACE/channel" || exit 1
+          mv "${PACKAGE_NAME}"-*.conda "$GITHUB_WORKSPACE/channel/osx-64" || exit 1
+          conda index "$GITHUB_WORKSPACE/channel" || exit 1
+          # Test channel
+          conda search "$PACKAGE_NAME" -c "$GITHUB_WORKSPACE/channel" --override-channels --info --json > "$GITHUB_WORKSPACE/ver.json"
+          cat ver.json
+
+      - name: Collect dependencies
+        shell: bash -el {0}
+        run: |
+          CHANNELS=(-c "$GITHUB_WORKSPACE/channel" -c conda-forge -c conda-forge/label/python_rc --override-channels)
+          PACKAGE_VERSION="$(python -c "${VER_SCRIPT1} ${VER_SCRIPT2}")"
+          export PACKAGE_VERSION
+          conda create -n "${{ env.TEST_ENV_NAME }}" "$PACKAGE_NAME=$PACKAGE_VERSION" "python=${{ matrix.python }}" "${CHANNELS[@]}" --only-deps --dry-run > lockfile
+          cat lockfile
+
+      - name: Cache conda packages
+        uses: actions/cache@27d5ce7f107fe9357f9df03efb73ab90386fccae # v5.0.5
+        env:
+          CACHE_NUMBER: 0  # Increase to reset cache
+        with:
+          path: /Users/runner/conda_pkgs_dir
+          key:
+            ${{ runner.os }}-conda-${{ env.CACHE_NUMBER }}-python-${{ matrix.python }}-${{hashFiles('lockfile') }}
+          restore-keys: |
+            ${{ runner.os }}-conda-${{ env.CACHE_NUMBER }}-python-${{ matrix.python }}-
+            ${{ runner.os }}-conda-${{ env.CACHE_NUMBER }}-
+
+      - name: Install mkl-service
+        shell: bash -el {0}
+        run: |
+          CHANNELS=(-c "$GITHUB_WORKSPACE/channel" -c conda-forge -c conda-forge/label/python_rc --override-channels)
+          PACKAGE_VERSION="$(python -c "${VER_SCRIPT1} ${VER_SCRIPT2}")"
+          export PACKAGE_VERSION
+          conda create -n "${{ env.TEST_ENV_NAME }}" "$PACKAGE_NAME=$PACKAGE_VERSION" pytest "python=${{ matrix.python }}" "${CHANNELS[@]}"
+          # Test installed packages
+          conda list -n "${{ env.TEST_ENV_NAME }}"
+
+      - name: Run tests
+        shell: bash -el {0}
+        run: |
+          conda activate ${{ env.TEST_ENV_NAME }}
+          pytest -vv --pyargs ${{ env.MODULE_NAME }}

CHANGELOG.md

@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Added
 
 ### Changed
+* Make `mkl-service` backward compatibility from MKL 2026.0 down to at least 2023.2 [gh-193](https://github.com/IntelPython/mkl-service/pull/193)
 
 ### Fixed
 * Changed insecure HTTP URLs to HTTPS in `pyproject.toml` and conda recipe files for improved security

conda-recipe-cf/conda_build_config.yaml

@@ -1,16 +1,14 @@
 c_compiler:                   # [linux]
     - gcc                     # [linux]
-cxx_compiler:                 # [linux]
-    - gxx                     # [linux]
-cxx_compiler_version:         # [linux]
-    - '14'                    # [linux]
 c_stdlib:                     # [linux]
     - sysroot                 # [linux]
 c_stdlib_version:             # [linux]
     - '2.28'                  # [linux]
+c_compiler:                   # [osx]
+    - clang                   # [osx]
+c_stdlib:                     # [osx]
+    - macosx_deployment_target  # [osx]
 c_stdlib:                     # [win]
     - vs                      # [win]
-cxx_compiler:                 # [win]
-    - vs2022                  # [win]
 c_compiler:                   # [win]
     - vs2022                  # [win]

conda-recipe-cf/meta.yaml

@@ -7,6 +7,7 @@ source:
 
 build:
     number: {{ GIT_DESCRIBE_NUMBER }}
+    skip: true  # [osx and arm64]
     script_env:
       - WHEELS_OUTPUT_FOLDER
     ignore_run_exports:
@@ -22,7 +23,8 @@ requirements:
       - python-gil     # [py>=314]
       - pip >=25.0
       - setuptools >=77
-      - mkl-devel
+      - mkl-devel  # [not osx]
+      - mkl-devel <2024 # [osx]
       - cython
       - wheel >=0.45.1
       - python-build >=1.2.2

conda-recipe/conda_build_config.yaml

@@ -1,16 +1,10 @@
-c_compiler:                   # [linux]
-    - gcc                     # [linux]
-cxx_compiler:                 # [linux]
-    - gxx                     # [linux]
-cxx_compiler_version:         # [linux]
-    - '14'                    # [linux]
-c_stdlib:                     # [linux]
-    - sysroot                 # [linux]
-c_stdlib_version:             # [linux]
-    - '2.28'                  # [linux]
-c_stdlib:                     # [win]
-    - vs                      # [win]
-cxx_compiler:                 # [win]
-    - vs2022                  # [win]
-c_compiler:                   # [win]
-    - vs2022                  # [win]
+c_compiler:                     # [linux]
+    - gcc                       # [linux]
+c_stdlib:                       # [linux]
+    - sysroot                   # [linux]
+c_stdlib_version:               # [linux]
+    - '2.28'                    # [linux]
+c_stdlib:                       # [win]
+    - vs                        # [win]
+c_compiler:                     # [win]
+    - vs2022                    # [win]

mkl/_mkl_service.pxd

@@ -59,7 +59,6 @@ cdef extern from "mkl.h":
     int MKL_CBWR_AVX2
     int MKL_CBWR_AVX512
     int MKL_CBWR_AVX512_E1
-    int MKL_CBWR_AVX10
 
     int MKL_CBWR_SUCCESS
     int MKL_CBWR_ERR_INVALID_SETTINGS
@@ -74,12 +73,10 @@ cdef extern from "mkl.h":
     int MKL_ENABLE_AVX512_E3
     int MKL_ENABLE_AVX512_E4
     int MKL_ENABLE_AVX512_E1
-    int MKL_ENABLE_AVX512_E5
     int MKL_ENABLE_AVX512
     int MKL_ENABLE_AVX2
     int MKL_ENABLE_AVX2_E1
     int MKL_ENABLE_SSE4_2
-    int MKL_ENABLE_AVX10
 
     # MPI Implementation Constants
     int MKL_BLACS_CUSTOM
@@ -169,3 +166,62 @@ cdef extern from "mkl.h":
     int vmlSetErrStatus(const MKL_INT status)
     int vmlGetErrStatus()
     int vmlClearErrStatus()
+
+# version-compat shim
+cdef extern from *:
+    """
+    #include <mkl.h>
+
+    /* define constants removed in 2026.0 if undefined */
+    #ifndef MKL_CBWR_SSSE3
+        #define MKL_CBWR_SSSE3 -1
+    #endif
+    #ifndef MKL_CBWR_SSE4_1
+        #define MKL_CBWR_SSE4_1 -1
+    #endif
+    #ifndef MKL_CBWR_AVX
+        #define MKL_CBWR_AVX -1
+    #endif
+    #ifndef MKL_CBWR_AVX512_MIC
+        #define MKL_CBWR_AVX512_MIC -1
+    #endif
+    #ifndef MKL_CBWR_AVX512_MIC_E1
+        #define MKL_CBWR_AVX512_MIC_E1 -1
+    #endif
+
+    #ifndef MKL_ENABLE_AVX512_MIC_E1
+        #define MKL_ENABLE_AVX512_MIC_E1 -1
+    #endif
+    #ifndef MKL_ENABLE_AVX512_MIC
+        #define MKL_ENABLE_AVX512_MIC -1
+    #endif
+    #ifndef MKL_ENABLE_AVX
+        #define MKL_ENABLE_AVX -1
+    #endif
+
+    /* define constants from 2026.0 if undefined */
+    #ifndef MKL_CBWR_AVX10
+        #define MKL_CBWR_AVX10 -2
+    #endif
+
+    #ifndef MKL_ENABLE_AVX512_E5
+        #define MKL_ENABLE_AVX512_E5 -2
+    #endif
+    #ifndef MKL_ENABLE_AVX10
+        #define MKL_ENABLE_AVX10 -2
+    #endif
+    """
+    int MKL_CBWR_SSSE3
+    int MKL_CBWR_SSE4_1
+    int MKL_CBWR_AVX
+    int MKL_CBWR_AVX512_MIC
+    int MKL_CBWR_AVX512_MIC_E1
+
+    int MKL_ENABLE_AVX512_MIC_E1
+    int MKL_ENABLE_AVX512_MIC
+    int MKL_ENABLE_AVX
+
+    int MKL_CBWR_AVX10
+
+    int MKL_ENABLE_AVX512_E5
+    int MKL_ENABLE_AVX10