Conda forge blas

.github/workflows/conda-forge.yml

@@ -0,0 +1,81 @@
+name: conda-forge BLAS
+
+# Builds against conda-forge's BLAS packages, which ship no vendor CMake config
+# (Windows) and split CBLAS into libcblas (Linux), as the sparsediffpy
+# conda-forge recipe does.
+
+on:
+  push:
+    branches: [main, development]
+  pull_request:
+    branches: [main, development]
+
+jobs:
+  build:
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-latest, windows-latest]
+
+    defaults:
+      run:
+        shell: bash -el {0}
+
+    steps:
+      - uses: actions/checkout@v5
+
+      - uses: conda-incubator/setup-miniconda@v3
+        with:
+          miniforge-version: latest
+          activate-environment: build
+          conda-remove-defaults: "true"
+
+      - name: Install conda-forge packages (Linux)
+        if: runner.os == 'Linux'
+        run: >
+          conda install -y cmake ninja c-compiler blas-devel
+          "libblas=*=*netlib" "libcblas=*=*netlib"
+
+      - name: Install conda-forge packages (Windows)
+        if: runner.os == 'Windows'
+        run: conda install -y cmake openblas libopenblas
+
+      - name: Configure (Linux)
+        if: runner.os == 'Linux'
+        run: >
+          cmake -B build -S . -G Ninja
+          -DCMAKE_BUILD_TYPE=Release
+          -DCMAKE_PREFIX_PATH="$CONDA_PREFIX"
+          -DCMAKE_C_FLAGS="-isystem $CONDA_PREFIX/include"
+          -DBLA_VENDOR=Generic
+
+      - name: Configure (Windows)
+        if: runner.os == 'Windows'
+        run: >
+          cmake -B build -S .
+          -DCMAKE_PREFIX_PATH="$CONDA_PREFIX/Library"
+
+      - name: Show BLAS selection
+        run: grep -E '^(BLAS_|CBLAS_LIBRARY|OPENBLAS_|OpenBLAS_DIR)' build/CMakeCache.txt || true
+
+      - name: Build
+        run: cmake --build build --config Release
+
+      - name: Run tests
+        run: cd build && ctest -C Release --output-on-failure
+
+      # Like conda-forge's pinning, build against netlib so the binary records
+      # the switchable libblas.so.3/libcblas.so.3 SONAMEs (the openblas variant
+      # is a symlink to libopenblas.so.0).
+      - name: Check libcblas is linked explicitly (Linux)
+        if: runner.os == 'Linux'
+        run: |
+          readelf -d build/all_tests | grep NEEDED
+          readelf -d build/all_tests | grep -q 'libcblas\.so\.3'
+
+      - name: Re-run tests after switching to OpenBLAS (Linux)
+        if: runner.os == 'Linux'
+        run: |
+          conda install -y "libblas=*=*openblas" "libcblas=*=*openblas"
+          cd build && ctest -C Release --output-on-failure

CMakeLists.txt

@@ -21,9 +21,22 @@ else()
   message(STATUS "Build type: ${CMAKE_BUILD_TYPE}")
 endif()
 
+# MSVC warnings-as-errors: on for standalone builds, off for Python builds so
+# downstream toolchains (e.g. conda-forge) aren't broken by new MSVC warnings
+if(SKBUILD)
+    set(_sde_werror_default OFF)
+else()
+    set(_sde_werror_default ON)
+endif()
+option(SDE_WARNINGS_AS_ERRORS "Treat MSVC warnings as errors (/WX)"
+       ${_sde_werror_default})
+
 # Warning flags (compiler-specific)
 if(MSVC)
-    add_compile_options(/W4 /WX)
+    add_compile_options(/W4)
+    if(SDE_WARNINGS_AS_ERRORS)
+        add_compile_options(/WX)
+    endif()
 else()
     add_compile_options(
         -Wall                  # Enable most warnings
@@ -66,10 +79,36 @@ if(APPLE)
     find_library(ACCELERATE_FRAMEWORK Accelerate)
     target_link_libraries(dnlp_diff ${ACCELERATE_FRAMEWORK})
 elseif(MSVC)
-    find_package(OpenBLAS CONFIG REQUIRED)
-    target_link_libraries(dnlp_diff OpenBLAS::OpenBLAS)
+    find_package(OpenBLAS CONFIG QUIET)
+    if(TARGET OpenBLAS::OpenBLAS)
+        # vcpkg
+        target_link_libraries(dnlp_diff OpenBLAS::OpenBLAS)
+    else()
+        # e.g. conda-forge's openblas ships openblas.lib and
+        # include/openblas/cblas.h, but no imported target
+        find_library(OPENBLAS_LIBRARY NAMES openblas libopenblas REQUIRED)
+        get_filename_component(_sde_openblas_libdir "${OPENBLAS_LIBRARY}" DIRECTORY)
+        get_filename_component(_sde_openblas_prefix "${_sde_openblas_libdir}" DIRECTORY)
+        find_path(OPENBLAS_INCLUDE_DIR cblas.h
+                  HINTS "${_sde_openblas_prefix}/include"
+                  PATH_SUFFIXES openblas REQUIRED)
+        target_link_libraries(dnlp_diff ${OPENBLAS_LIBRARY})
+        target_include_directories(dnlp_diff PUBLIC ${OPENBLAS_INCLUDE_DIR})
+    endif()
 else()
     find_package(BLAS REQUIRED)
+    # conda-forge splits the CBLAS interface into libcblas next to libblas. Link
+    # it explicitly (and before BLAS) so the package keeps working when users
+    # switch BLAS implementations, even if the build-time libblas exports cblas_*.
+    if(BLAS_LIBRARIES)
+        list(GET BLAS_LIBRARIES 0 _sde_blas_lib)
+        get_filename_component(_sde_blas_dir "${_sde_blas_lib}" DIRECTORY)
+        find_library(CBLAS_LIBRARY NAMES cblas
+                     HINTS "${_sde_blas_dir}" NO_DEFAULT_PATH)
+    endif()
+    if(CBLAS_LIBRARY)
+        target_link_libraries(dnlp_diff ${CBLAS_LIBRARY})
+    endif()
     target_link_libraries(dnlp_diff ${BLAS_LIBRARIES})
 endif()