crazy cmake stuff

Author: NicolasHug

.github/workflows/windows_source_build.yaml

@@ -147,7 +147,12 @@ jobs:
           
           # On Windows, try to work around the dependency linking issues
           # by setting CMAKE_ARGS to use dynamic linking where possible
-          export CMAKE_ARGS="-DCMAKE_BUILD_TYPE=Release -DTORCHCODEC_DISABLE_COMPILE_WARNING_AS_ERROR=ON"
+          conda_env_path=$(conda info --base)/envs/build
+          library_lib_path="$conda_env_path/Library/lib"
+          
+          export CMAKE_ARGS="-DCMAKE_BUILD_TYPE=Release -DTORCHCODEC_DISABLE_COMPILE_WARNING_AS_ERROR=ON -DCMAKE_LIBRARY_PATH=$library_lib_path"
+          
+          echo "CMAKE_ARGS: $CMAKE_ARGS"
           
           # Try to create symlinks for missing .lib files if the DLLs exist
           conda_env_path=$(conda info --base)/envs/build

src/torchcodec/_core/CMakeLists.txt

@@ -65,6 +65,12 @@ function(make_torchcodec_sublibrary
         PUBLIC
         ${library_dependencies}
     )
+    
+    # Debug output for Windows builds
+    if(WIN32)
+        message(STATUS "Created library: ${library_name}")
+        message(STATUS "Library dependencies: ${library_dependencies}")
+    endif()
 endfunction()
 
 function(make_torchcodec_libraries
@@ -198,6 +204,45 @@ function(make_torchcodec_libraries
         ${pybind_ops_library_name}
     )
 
+    # The install step is invoked within CMakeBuild.build_library() in
+    # setup.py and just copies the built files from the temp
+    # cmake/setuptools build folder into the CMAKE_INSTALL_PREFIX folder. We
+    # still need to manually pass "DESTINATION ..." for cmake to copy those
+    # files in CMAKE_INSTALL_PREFIX instead of CMAKE_INSTALL_PREFIX/lib.
+    install(
+        TARGETS ${all_libraries}
+        LIBRARY DESTINATION ${CMAKE_INSTALL_PREFIX}
+        RUNTIME DESTINATION ${CMAKE_INSTALL_PREFIX}  # For Windows DLLs
+ibrary to prevent
+    # stray initialization of py::objects. The rest of the object code must
+    # match. See:
+    #   https://pybind11.readthedocs.io/en/stable/faq.html#someclass-declared-with-greater-visibility-than-the-type-of-its-field-someclass-member-wattributes
+    if(NOT WIN32)  # TODO unify WIN detection
+        target_compile_options(
+            ${pybind_ops_library_name}
+            PUBLIC
+            "-fvisibility=hidden"
+        )
+    endif()
+    if(APPLE)  # TODO unify APPLE detection
+        # If we don't make sure this flag is set, we run into segfauls at import
+        # time on Mac. See:
+        # https://github.com/pybind/pybind11/issues/3907#issuecomment-1170412764
+        target_link_options(
+            ${pybind_ops_library_name}
+            PUBLIC
+            "LINKER:-undefined,dynamic_lookup"
+        )
+    endif()
+
+    # Install all libraries.
+    set(
+        all_libraries
+        ${decoder_library_name}
+        ${custom_ops_library_name}
+        ${pybind_ops_library_name}
+    )
+
     # The install step is invoked within CMakeBuild.build_library() in
     # setup.py and just copies the built files from the temp
     # cmake/setuptools build folder into the CMAKE_INSTALL_PREFIX folder. We
@@ -246,6 +291,21 @@ else()
         libswscale
     )
 
+    # On Windows, explicitly add the conda library directory to the linker search path
+    if(WIN32 AND DEFINED ENV{CONDA_PREFIX})
+        link_directories("$ENV{CONDA_PREFIX}/Library/lib")
+        message(STATUS "Added conda library directory to linker search path: $ENV{CONDA_PREFIX}/Library/lib")
+        
+        # Also add the library path to CMAKE_PREFIX_PATH for better library finding
+        list(APPEND CMAKE_PREFIX_PATH "$ENV{CONDA_PREFIX}/Library")
+        message(STATUS "Added conda prefix to CMAKE_PREFIX_PATH: $ENV{CONDA_PREFIX}/Library")
+        
+        # Debug: Show what LIBAV variables are set
+        message(STATUS "LIBAV_INCLUDE_DIRS: ${LIBAV_INCLUDE_DIRS}")
+        message(STATUS "LIBAV_LIBRARY_DIRS: ${LIBAV_LIBRARY_DIRS}")
+        message(STATUS "LIBAV_LIBRARIES: ${LIBAV_LIBRARIES}")
+    endif()
+
     # Split libavcodec's version string by '.' and convert it to a list
     string(REPLACE "." ";" libavcodec_version_list ${LIBAV_libavcodec_VERSION})
     # Get the first element of the list, which is the major version