Sync some features with anaconda's recipe

recipe/bld.bat

@@ -7,6 +7,12 @@ if EXIST pyproject.toml (
   if %ERRORLEVEL% neq 0 exit 1
 )
 
+@REM The PyTorch test suite includes some symlinks, which aren't resolved on Windows, leading to packaging errors.
+@REM ATTN! These change and have to be updated manually, often with each release.
+@REM (no current symlinks being packaged. Leaving this information here as it took some months to find the issue. Look out
+@REM for a failure with error message: "conda_package_handling.exceptions.ArchiveCreationError: <somefile> Cannot stat
+@REM while writing file")
+
 set PYTORCH_BUILD_VERSION=%PKG_VERSION%
 @REM Always pass 0 to avoid appending ".post" to version string.
 @REM https://github.com/conda-forge/pytorch-cpu-feedstock/issues/315
@@ -97,6 +103,10 @@ if not "%cuda_compiler_version%" == "None" (
 
 set DISTUTILS_USE_SDK=1
 
+@REM Use our Pybind11, Eigen
+set USE_SYSTEM_PYBIND11=1
+set USE_SYSTEM_EIGEN_INSTALL=1
+
 set CMAKE_INCLUDE_PATH=%LIBRARY_PREFIX%\include
 set LIB=%LIBRARY_PREFIX%\lib;%LIB%
 
@@ -128,7 +138,7 @@ set "USE_LITE_PROTO=ON"
 set "USE_OPENMP=OFF"
 
 @REM The activation script for cuda-nvcc doesnt add the CUDA_CFLAGS on windows.
-@REM Therefor we do this manually here. See:
+@REM Therefore we do this manually here. See:
 @REM https://github.com/conda-forge/cuda-nvcc-feedstock/issues/47
 echo "CUDA_CFLAGS=%CUDA_CFLAGS%"
 set "CUDA_CFLAGS=-I%PREFIX%/Library/include -I%BUILD_PREFIX%/Library/include"
@@ -183,19 +193,12 @@ if "%PKG_NAME%" == "libtorch" (
     pushd torch-%PKG_VERSION%
     if %ERRORLEVEL% neq 0 exit 1
 
-    @REM Do not package `fmt.lib` (and its metadata); delete it before the move into
-    @REM %LIBRARY_BIN% because it may exist in host before installation already
-    del torch\lib\fmt.lib torch\lib\pkgconfig\fmt.pc
-    if %ERRORLEVEL% neq 0 exit 1
-    @REM also delete rest of fmt metadata
-    rmdir /s /q torch\lib\cmake\fmt
-
     @REM Move the binaries into the packages site-package directory
     @REM the only content of torch\bin, {asmjit,fbgemm}.dll, also exists in torch\lib
-    robocopy /NP /NFL /NDL /NJH /E torch\lib\ %LIBRARY_BIN%\ torch*.dll c10.dll shm.dll asmjit.dll fbgemm.dll
+    robocopy /NP /NFL /NDL /NJH /E torch\bin\ %LIBRARY_BIN%\ torch*.dll c10.dll shm.dll asmjit.dll fbgemm.dll
     robocopy /NP /NFL /NDL /NJH /E torch\lib\ %LIBRARY_LIB%\ torch*.lib c10.lib shm.lib asmjit.lib fbgemm.lib
     if not "%cuda_compiler_version%" == "None" (
-        robocopy /NP /NFL /NDL /NJH /E torch\lib\ %LIBRARY_BIN%\ c10_cuda.dll caffe2_nvrtc.dll
+        robocopy /NP /NFL /NDL /NJH /E torch\bin\ %LIBRARY_BIN%\ c10_cuda.dll caffe2_nvrtc.dll
         robocopy /NP /NFL /NDL /NJH /E torch\lib\ %LIBRARY_LIB%\ c10_cuda.lib caffe2_nvrtc.lib
     )
     robocopy /NP /NFL /NDL /NJH /E torch\share\ %LIBRARY_PREFIX%\share
@@ -216,7 +219,7 @@ if "%PKG_NAME%" == "libtorch" (
     if %ERRORLEVEL% neq 0 exit 1
 ) else if "%PKG_NAME%" == "pytorch" (
     @REM Move libtorch_python and remove the other directories afterwards.
-    robocopy /NP /NFL /NDL /NJH /E %SP_DIR%\torch\lib\ %LIBRARY_BIN%\ torch_python.dll
+    robocopy /NP /NFL /NDL /NJH /E %SP_DIR%\torch\bin\ %LIBRARY_BIN%\ torch_python.dll
     robocopy /NP /NFL /NDL /NJH /E %SP_DIR%\torch\lib\ %LIBRARY_LIB%\ torch_python.lib
     robocopy /NP /NFL /NDL /NJH /E %SP_DIR%\torch\lib\ %LIBRARY_LIB%\ _C.lib
     rmdir /s /q %SP_DIR%\torch\lib

recipe/build.sh

@@ -1,9 +1,11 @@
 #!/bin/bash
 
-echo "=== Building ${PKG_NAME} (py: ${PY_VER}) ==="
-
 set -ex
 
+echo "#########################################################################"
+echo "Building ${PKG_NAME} (py: ${PY_VER}) using BLAS implementation $blas_impl"
+echo "#########################################################################"
+
 # This is used to detect if it's in the process of building pytorch
 export IN_PYTORCH_BUILD=1
 
@@ -20,9 +22,22 @@ rm -rf pyproject.toml
 export USE_CUFILE=0
 export USE_NUMA=0
 export USE_ITT=0
+
+#################### ADJUST COMPILER AND LINKER FLAGS #####################
+# Pytorch's build system doesn't like us setting the c++ standard through CMAKE_CXX_FLAGS
+# and will issue a warning.  We need to use at least C++17 to match the abseil ABI, see
+# https://github.com/conda-forge/abseil-cpp-feedstock/issues/45, which pytorch 2.5 uses already:
+# https://github.com/pytorch/pytorch/blob/v2.5.1/CMakeLists.txt#L36-L48
+export CXXFLAGS="$(echo $CXXFLAGS | sed 's/-std=c++[0-9][0-9]//g')"
+# The below three lines expose symbols that would otherwise be hidden or
+# optimised away. They were here before, so removing them would potentially
+# break users' programs
 export CFLAGS="$(echo $CFLAGS | sed 's/-fvisibility-inlines-hidden//g')"
 export CXXFLAGS="$(echo $CXXFLAGS | sed 's/-fvisibility-inlines-hidden//g')"
 export LDFLAGS="$(echo $LDFLAGS | sed 's/-Wl,--as-needed//g')"
+# The default conda LDFLAGs include -Wl,-dead_strip_dylibs, which removes all the
+# MKL sequential, core, etc. libraries, resulting in a "Symbol not found: _mkl_blas_caxpy"
+# error on osx-64.
 export LDFLAGS="$(echo $LDFLAGS | sed 's/-Wl,-dead_strip_dylibs//g')"
 export LDFLAGS_LD="$(echo $LDFLAGS_LD | sed 's/-dead_strip_dylibs//g')"
 if [[ "$c_compiler" == "clang" ]]; then
@@ -45,6 +60,7 @@ fi
 # can be imported on system without a GPU
 LDFLAGS="${LDFLAGS//-Wl,-z,now/-Wl,-z,lazy}"
 
+################ CONFIGURE CMAKE FOR CONDA ENVIRONMENT ###################
 export CMAKE_GENERATOR=Ninja
 export CMAKE_LIBRARY_PATH=$PREFIX/lib:$PREFIX/include:$CMAKE_LIBRARY_PATH
 export CMAKE_PREFIX_PATH=$PREFIX
@@ -73,6 +89,8 @@ export USE_SYSTEM_SLEEF=1
 # use our protobuf
 export BUILD_CUSTOM_PROTOBUF=OFF
 rm -rf $PREFIX/bin/protoc
+export USE_SYSTEM_PYBIND11=1
+export USE_SYSTEM_EIGEN_INSTALL=1
 
 # prevent six from being downloaded
 > third_party/NNPACK/cmake/DownloadSix.cmake
@@ -98,18 +116,29 @@ if [[ "${CI}" == "github_actions" ]]; then
     # reduce parallelism to avoid getting OOM-killed on
     # cirun-openstack-gpu-2xlarge, which has 32GB RAM, 8 CPUs
     export MAX_JOBS=4
-else
+elif [[ "${CI}" == "azure" ]]; then
     export MAX_JOBS=${CPU_COUNT}
-fi
-
-if [[ "$blas_impl" == "generic" ]]; then
-    # Fake openblas
-    export BLAS=OpenBLAS
-    export OpenBLAS_HOME=${PREFIX}
 else
-    export BLAS=MKL
+    # Leave a spare core for other tasks, per common practice.
+    # Reducing further can help with out-of-memory errors.
+    export MAX_JOBS=$((CPU_COUNT > 1 ? CPU_COUNT - 1 : 1))
 fi
 
+case "$blas_impl" in
+    "generic")
+        # Fake openblas
+        export BLAS=OpenBLAS
+        export OpenBLAS_HOME=${PREFIX}
+        ;;
+    "mkl")
+        export BLAS=MKL
+        ;;
+    *)
+        echo "[ERROR] Unsupported BLAS implementation '${blas_impl}'" >&2
+        exit 1
+        ;;
+esac
+
 if [[ "$PKG_NAME" == "pytorch" ]]; then
   # Trick Cmake into thinking python hasn't changed
   sed "s/3\.12/$PY_VER/g" build/CMakeCache.txt.orig > build/CMakeCache.txt
@@ -163,12 +192,24 @@ elif [[ ${cuda_compiler_version} != "None" ]]; then
             echo "unknown CUDA arch, edit build.sh"
             exit 1
     esac
+
+    # Compatibility matrix for update: https://en.wikipedia.org/wiki/CUDA#GPUs_supported
+    # Warning from pytorch v1.12.1: In the future we will require one to
+    # explicitly pass TORCH_CUDA_ARCH_LIST to cmake instead of implicitly
+    # setting it as an env variable.
+    # Doing this is nontrivial given that we're using setup.py as an entry point, but should
+    # be addressed to pre-empt upstream changing it, as it probably won't result in a failed
+    # configuration.
+    #
+    # See:
+    # https://pytorch.org/docs/stable/cpp_extension.html (Compute capabilities)
+    # https://github.com/pytorch/pytorch/blob/main/.ci/manywheel/build_cuda.sh
     case ${cuda_compiler_version} in
-        12.6)
+        12.[0-6])
             export TORCH_CUDA_ARCH_LIST="5.0;6.0;6.1;7.0;7.5;8.0;8.6;8.9;9.0+PTX"
             ;;
         *)
-            echo "unsupported cuda version. edit build.sh"
+            echo "No CUDA architecture list exists for CUDA v${cuda_compiler_version}. See build.sh for information on adding one."
             exit 1
     esac
     export TORCH_NVCC_FLAGS="-Xfatbin -compress-all"
@@ -203,15 +244,16 @@ case ${PKG_NAME} in
 
     mv build/lib.*/torch/bin/* ${PREFIX}/bin/
     mv build/lib.*/torch/lib/* ${PREFIX}/lib/
-    mv build/lib.*/torch/share/* ${PREFIX}/share/
+    # need to merge these now because we're using system pybind11, meaning the destination directory is not empty
+    rsync -a build/lib.*/torch/share/* ${PREFIX}/share/
     mv build/lib.*/torch/include/{ATen,caffe2,tensorpipe,torch,c10} ${PREFIX}/include/
     rm ${PREFIX}/lib/libtorch_python.*
 
     # Keep the original backed up to sed later
     cp build/CMakeCache.txt build/CMakeCache.txt.orig
     ;;
   pytorch)
-    $PREFIX/bin/python -m pip install . --no-deps -vvv --no-clean \
+    $PREFIX/bin/python -m pip install . --no-deps --no-build-isolation -vvv --no-clean \
         | sed "s,${CXX},\$\{CXX\},g" \
         | sed "s,${PREFIX},\$\{PREFIX\},g"
     # Keep this in ${PREFIX}/lib so that the library can be found by

recipe/cmake_test/CMakeLists.txt

@@ -0,0 +1,4 @@
+project(cf_dummy LANGUAGES C CXX)
+cmake_minimum_required(VERSION 3.12)
+find_package(Torch CONFIG REQUIRED)
+find_package(ATen CONFIG REQUIRED)