Add full SYCL support for Windows builds

.github/workflows/macos.yml

@@ -66,9 +66,8 @@ jobs:
 
       - name: Install dependencies
         run: |
-          brew install ccache glslang spirv-cross
-          # Fix gfortran not found issue. 
-          brew install gcc
+          brew install ccache glslang spirv-cross gcc
+          # Fix gfortran not found issue
           ln -s $(brew --prefix gcc)/bin/gfortran-* /usr/local/bin/gfortran
 
           ccache -M 2G  # See .github/workflows/readme.md for ccache strategy.

.gitignore

@@ -27,6 +27,7 @@ cmake-build-release/
 util/pip_package/dist/
 doxygen/
 node_modules/
+.yarn
 
 # Editor files
 *.*~

3rdparty/README_SYCL.md

@@ -98,9 +98,15 @@ Open3D is designed to make use of the SYCL GPU devices.
 
 ## List of oneAPI Python packages
 
-To make `pip install open3d` works out-of-the box on SYCL-enabled platforms,
-we can utilize runtime libraries released via PyPI. This feature needs to be
-implemented.
+Open3D SYCL wheels declare a dependency on `dpcpp-cpp-rt` (see
+`python/requirements_sycl.txt`). Pip installs the transitive Intel runtime
+packages into the same Python environment. On Linux, ``pybind`` RPATH finds
+``<venv>/lib``; on Windows, ``open3d/__init__.py`` registers
+``site-packages/*.data/data/Library/bin`` with ``add_dll_directory``.
+
+Windows CI (xpu) installs build-time oneAPI from Intel Base + HPC webimages with
+selective components only (``util/ci_install_oneapi_windows_sycl.ps1``, aligned
+with `oneapi-ci <https://github.com/oneapi-src/oneapi-ci/tree/0804a4c9281440d8a91ac0680388b101e5f673ad>`_).
 
 User:
 - https://pypi.org/user/IntelAutomationEngineering/

3rdparty/civetweb/civetweb.cmake

@@ -19,7 +19,16 @@ ExternalProject_Add(
         -DCIVETWEB_DISABLE_CGI=ON
         -DCMAKE_INSTALL_PREFIX=<INSTALL_DIR>
         -DCMAKE_POLICY_VERSION_MINIMUM=3.5
-        -DCMAKE_CXX_FLAGS="-D_GLIBCXX_USE_CXX11_ABI=$<BOOL:${GLIBCXX_USE_CXX11_ABI}> $<$<PLATFORM_ID:Windows>:/EHsc>"
+        # Note: on Windows, keep this as a single flag (no embedded space by
+        # combining with another flag in the same string). The Intel
+        # oneAPI DPC++/C++ compiler (icx), used when BUILD_SYCL_MODULE=ON,
+        # parses each CMAKE_ARGS string as one literal argv token; a
+        # combined "-D<macro> /EHsc" string gets misparsed by icx as the
+        # macro's value swallowing "/EHsc", silently leaving exceptions
+        # disabled (MSVC cl.exe tolerates this, icx does not). Since
+        # _GLIBCXX_USE_CXX11_ABI only matters for libstdc++ (not used on
+        # Windows/MSVC STL), it is safe to only set one flag per platform.
+        -DCMAKE_CXX_FLAGS=$<IF:$<PLATFORM_ID:Windows>,/EHsc,-D_GLIBCXX_USE_CXX11_ABI=$<BOOL:${GLIBCXX_USE_CXX11_ABI}>>
         ${ExternalProject_CMAKE_ARGS_hidden}
     BUILD_BYPRODUCTS
         <INSTALL_DIR>/${Open3D_INSTALL_LIB_DIR}/${CMAKE_STATIC_LIBRARY_PREFIX}civetweb${CMAKE_STATIC_LIBRARY_SUFFIX}

3rdparty/embree/embree.cmake

@@ -50,22 +50,43 @@ endif()
 
 
 if(WIN32)
-    set(WIN_CMAKE_ARGS "-DCMAKE_CXX_FLAGS_DEBUG=$<IF:$<BOOL:${STATIC_WINDOWS_RUNTIME}>,/MTd,/MDd> ${CMAKE_CXX_FLAGS_DEBUG_INIT}"
-                       "-DCMAKE_CXX_FLAGS_RELEASE=$<IF:$<BOOL:${STATIC_WINDOWS_RUNTIME}>,/MT,/MD> ${CMAKE_CXX_FLAGS_RELEASE_INIT}"
-                       "-DCMAKE_CXX_FLAGS_RELWITHDEBINFO=$<IF:$<BOOL:${STATIC_WINDOWS_RUNTIME}>,/MT,/MD> ${CMAKE_CXX_FLAGS_RELWITHDEBINFO_INIT}"
-                       "-DCMAKE_CXX_FLAGS_MINSIZEREL=$<IF:$<BOOL:${STATIC_WINDOWS_RUNTIME}>,/MT,/MD> ${CMAKE_CXX_FLAGS_MINSIZEREL_INIT}"
-                       "-DCMAKE_C_FLAGS_DEBUG=$<IF:$<BOOL:${STATIC_WINDOWS_RUNTIME}>,/MTd,/MDd> ${CMAKE_C_FLAGS_DEBUG_INIT}"
-                       "-DCMAKE_C_FLAGS_RELEASE=$<IF:$<BOOL:${STATIC_WINDOWS_RUNTIME}>,/MT,/MD> ${CMAKE_C_FLAGS_RELEASE_INIT}"
-                       "-DCMAKE_C_FLAGS_RELWITHDEBINFO=$<IF:$<BOOL:${STATIC_WINDOWS_RUNTIME}>,/MT,/MD> ${CMAKE_C_FLAGS_RELWITHDEBINFO_INIT}"
-                       "-DCMAKE_C_FLAGS_MINSIZEREL=$<IF:$<BOOL:${STATIC_WINDOWS_RUNTIME}>,/MT,/MD> ${CMAKE_C_FLAGS_MINSIZEREL_INIT}"
+    # icx.exe hard-errors ("invalid argument 'MT' not allowed with
+    # '-fsycl'") when compiling any translation unit with -fsycl together
+    # with the static (/MT, /MTd) MSVC runtime. Since embree's SYCL support
+    # (embree4_sycl, ze_wrapper) is built in the same ExternalProject
+    # configure/build as the non-SYCL ISA libs, force the dynamic runtime
+    # (/MD, /MDd) for all of embree's libs when BUILD_SYCL_MODULE=ON,
+    # regardless of STATIC_WINDOWS_RUNTIME. This also matches upstream
+    # embree's own Windows SYCL build docs, which never enable
+    # USE_STATIC_RUNTIME (default OFF) together with EMBREE_SYCL_SUPPORT.
+    if(BUILD_SYCL_MODULE)
+        set(EMBREE_USE_STATIC_RUNTIME OFF)
+    else()
+        set(EMBREE_USE_STATIC_RUNTIME ${STATIC_WINDOWS_RUNTIME})
+    endif()
+    set(WIN_CMAKE_ARGS "-DCMAKE_CXX_FLAGS_DEBUG=$<IF:$<BOOL:${EMBREE_USE_STATIC_RUNTIME}>,/MTd,/MDd> ${CMAKE_CXX_FLAGS_DEBUG_INIT}"
+                       "-DCMAKE_CXX_FLAGS_RELEASE=$<IF:$<BOOL:${EMBREE_USE_STATIC_RUNTIME}>,/MT,/MD> ${CMAKE_CXX_FLAGS_RELEASE_INIT}"
+                       "-DCMAKE_CXX_FLAGS_RELWITHDEBINFO=$<IF:$<BOOL:${EMBREE_USE_STATIC_RUNTIME}>,/MT,/MD> ${CMAKE_CXX_FLAGS_RELWITHDEBINFO_INIT}"
+                       "-DCMAKE_CXX_FLAGS_MINSIZEREL=$<IF:$<BOOL:${EMBREE_USE_STATIC_RUNTIME}>,/MT,/MD> ${CMAKE_CXX_FLAGS_MINSIZEREL_INIT}"
+                       "-DCMAKE_C_FLAGS_DEBUG=$<IF:$<BOOL:${EMBREE_USE_STATIC_RUNTIME}>,/MTd,/MDd> ${CMAKE_C_FLAGS_DEBUG_INIT}"
+                       "-DCMAKE_C_FLAGS_RELEASE=$<IF:$<BOOL:${EMBREE_USE_STATIC_RUNTIME}>,/MT,/MD> ${CMAKE_C_FLAGS_RELEASE_INIT}"
+                       "-DCMAKE_C_FLAGS_RELWITHDEBINFO=$<IF:$<BOOL:${EMBREE_USE_STATIC_RUNTIME}>,/MT,/MD> ${CMAKE_C_FLAGS_RELWITHDEBINFO_INIT}"
+                       "-DCMAKE_C_FLAGS_MINSIZEREL=$<IF:$<BOOL:${EMBREE_USE_STATIC_RUNTIME}>,/MT,/MD> ${CMAKE_C_FLAGS_MINSIZEREL_INIT}"
                        )
 else()
     set(WIN_CMAKE_ARGS "")
 endif()
 
 
 if(BUILD_SYCL_MODULE)
-    set(ISA_ARGS ${ISA_ARGS} -DCMAKE_CXX_COMPILER=icpx)
+    # On Windows, icx.exe (MSVC-compatible) handles C++ and SYCL (-fsycl).
+    # icpx.exe (GNU-like in oneAPI 2025.3+) conflicts with MSVC-style flags
+    # generated by CMake when using Ninja on Windows.
+    if(WIN32)
+        set(ISA_ARGS ${ISA_ARGS} -DCMAKE_CXX_COMPILER=icx)
+    else()
+        set(ISA_ARGS ${ISA_ARGS} -DCMAKE_CXX_COMPILER=icpx)
+    endif()
     set(ISA_ARGS ${ISA_ARGS} -DCMAKE_C_COMPILER=icx)
     set(ISA_ARGS ${ISA_ARGS} -DEMBREE_SYCL_SUPPORT=ON)
     list(APPEND ISA_LIBS embree4_sycl ze_wrapper)
@@ -102,7 +123,6 @@ ExternalProject_Add(
         <INSTALL_DIR>/${Open3D_INSTALL_LIB_DIR}/${CMAKE_STATIC_LIBRARY_PREFIX}sys${CMAKE_STATIC_LIBRARY_SUFFIX}
         <INSTALL_DIR>/${Open3D_INSTALL_LIB_DIR}/${CMAKE_STATIC_LIBRARY_PREFIX}math${CMAKE_STATIC_LIBRARY_SUFFIX}
         <INSTALL_DIR>/${Open3D_INSTALL_LIB_DIR}/${CMAKE_STATIC_LIBRARY_PREFIX}tasking${CMAKE_STATIC_LIBRARY_SUFFIX}
-        <INSTALL_DIR>/${Open3D_INSTALL_LIB_DIR}/${CMAKE_STATIC_LIBRARY_PREFIX}ze_wrapper${CMAKE_STATIC_LIBRARY_SUFFIX}
         ${ISA_BUILD_BYPRODUCTS}
 )
 

3rdparty/filament/filament_build.cmake

@@ -70,7 +70,7 @@ ExternalProject_Add(
         -DCMAKE_CXX_COMPILER_LAUNCHER=${CMAKE_CXX_COMPILER_LAUNCHER}
         -DCMAKE_CXX_FLAGS:STRING=${filament_cxx_flags}
         -DCMAKE_INSTALL_PREFIX=${FILAMENT_ROOT}
-        -DUSE_STATIC_CRT=${STATIC_WINDOWS_RUNTIME}
+        -DUSE_STATIC_CRT=$<IF:$<BOOL:${BUILD_SYCL_MODULE}>,OFF,${STATIC_WINDOWS_RUNTIME}>
         -DUSE_STATIC_LIBCXX=ON
         -DFILAMENT_SKIP_SDL2=ON
         -DFILAMENT_SKIP_SAMPLES=ON

3rdparty/filament/filament_download.cmake

@@ -15,7 +15,11 @@ else()
     if(WIN32)
         set(FILAMENT_URL https://github.com/google/filament/releases/download/v1.54.0/filament-v1.54.0-windows.tgz)
         set(FILAMENT_SHA256 370b85dbaf1a3be26a5a80f60c912f11887748ddd1c42796a83fe989f5805f7b)
-        if (STATIC_WINDOWS_RUNTIME)
+        # Note: when BUILD_SYCL_MODULE is ON, Open3D forces the dynamic
+        # (/MD, /MDd) MSVC runtime for the whole project regardless of
+        # STATIC_WINDOWS_RUNTIME (icx rejects -fsycl combined with the
+        # static runtime), so the prebuilt Filament libs must match.
+        if (STATIC_WINDOWS_RUNTIME AND NOT BUILD_SYCL_MODULE)
             string(APPEND lib_dir /x86_64/mt)
         else()
             string(APPEND lib_dir /x86_64/md)

3rdparty/find_dependencies.cmake

@@ -1356,7 +1356,10 @@ if(BUILD_GUI)
                 set(FILAMENT_RUNTIME_VER x86_64)
             endif()
         else()  # WIN32
-            if (STATIC_WINDOWS_RUNTIME)
+            # Match the prebuilt Filament archive's runtime selection in
+            # filament_download.cmake: SYCL builds always use the dynamic
+            # runtime regardless of STATIC_WINDOWS_RUNTIME.
+            if (STATIC_WINDOWS_RUNTIME AND NOT BUILD_SYCL_MODULE)
                 set(FILAMENT_RUNTIME_VER "x86_64/mt$<$<CONFIG:DEBUG>:d>")
             else()
                 set(FILAMENT_RUNTIME_VER "x86_64/md$<$<CONFIG:DEBUG>:d>")
@@ -1608,16 +1611,29 @@ if(OPEN3D_USE_ONEAPI_PACKAGES)
     set(MKL_THREADING tbb_thread)
     set(MKL_LINK static)
     find_package(MKL REQUIRED)
+    # oneAPI MKL's lib layout differs by platform: Linux nests libs under an
+    # "intel64" subdirectory, while Windows (verified with oneAPI 2025.3)
+    # places them directly in "lib".
+    if(WIN32)
+        set(MKL_LIB_DIR ${MKL_ROOT}/lib)
+    else()
+        set(MKL_LIB_DIR ${MKL_ROOT}/lib/intel64)
+    endif()
     open3d_import_3rdparty_library(3rdparty_mkl
         HIDDEN
         GROUPED
         INCLUDE_DIRS ${MKL_INCLUDE}/
-        LIB_DIR      ${MKL_ROOT}/lib/intel64
+        LIB_DIR      ${MKL_LIB_DIR}
         LIBRARIES    $<$<BOOL:${BUILD_SYCL_MODULE}>:mkl_sycl> mkl_intel_ilp64 mkl_tbb_thread mkl_core
     )
     if (BUILD_SYCL_MODULE)
     # target_link_options(3rdparty_mkl INTERFACE "-Wl,-export-dynamic")
-        target_link_libraries(3rdparty_mkl INTERFACE OpenCL)
+        if (WIN32)
+            find_package(OpenCL REQUIRED)
+            target_link_libraries(3rdparty_mkl INTERFACE OpenCL::OpenCL)
+        else()
+            target_link_libraries(3rdparty_mkl INTERFACE OpenCL)
+        endif()
     endif()
     # MKL definitions
     target_compile_options(3rdparty_mkl INTERFACE "$<$<PLATFORM_ID:Linux,Darwin>:$<$<COMPILE_LANGUAGE:CXX>:-m64>>")

3rdparty/googletest/googletest.cmake

@@ -14,3 +14,14 @@ FetchContent_Declare(
 
 FetchContent_MakeAvailable(ext_googletest)
 FetchContent_GetProperties(ext_googletest SOURCE_DIR GOOGLETEST_SOURCE_DIR)
+
+# Suppress -Wcharacter-conversion error in googletest when using IntelLLVM/ICX.
+# ICX's Clang front-end treats the implicit char16_t->char32_t conversion in
+# gtest-printers.h(524) as a hard error. Suppress it on FetchContent targets.
+if(CMAKE_CXX_COMPILER_ID MATCHES "IntelLLVM")
+    foreach(_gt_tgt gtest gtest_main gmock gmock_main)
+        if(TARGET ${_gt_tgt})
+            target_compile_options(${_gt_tgt} PRIVATE -Wno-character-conversion)
+        endif()
+    endforeach()
+endif()

3rdparty/jsoncpp/jsoncpp.cmake

@@ -2,6 +2,15 @@ include(ExternalProject)
 
 find_package(Git QUIET REQUIRED)
 
+# SYCL builds always force the dynamic (/MD, /MDd) MSVC runtime for the
+# whole project regardless of STATIC_WINDOWS_RUNTIME (icx rejects -fsycl
+# combined with the static runtime), so jsoncpp must match.
+if(BUILD_SYCL_MODULE)
+    set(JSONCPP_USE_STATIC_RUNTIME OFF)
+else()
+    set(JSONCPP_USE_STATIC_RUNTIME ${STATIC_WINDOWS_RUNTIME})
+endif()
+
 ExternalProject_Add(
     ext_jsoncpp
     PREFIX jsoncpp
@@ -19,7 +28,7 @@ ExternalProject_Add(
         -DBUILD_OBJECT_LIBS=OFF
         -DJSONCPP_WITH_TESTS=OFF
         -DJSONCPP_USE_CXX11_ABI=${GLIBCXX_USE_CXX11_ABI}
-        -DJSONCPP_STATIC_WINDOWS_RUNTIME=${STATIC_WINDOWS_RUNTIME}
+        -DJSONCPP_STATIC_WINDOWS_RUNTIME=${JSONCPP_USE_STATIC_RUNTIME}
         ${ExternalProject_CMAKE_ARGS_hidden}
     BUILD_BYPRODUCTS
         <INSTALL_DIR>/${Open3D_INSTALL_LIB_DIR}/${CMAKE_STATIC_LIBRARY_PREFIX}jsoncpp${CMAKE_STATIC_LIBRARY_SUFFIX}

3rdparty/libjpeg-turbo/libjpeg-turbo.cmake

@@ -35,7 +35,7 @@ else()
     message(STATUS "NASM assembler not found - libjpeg-turbo performance may suffer")
 endif()
 
-if (STATIC_WINDOWS_RUNTIME)
+if (STATIC_WINDOWS_RUNTIME AND NOT BUILD_SYCL_MODULE)
     set(WITH_CRT_DLL OFF)
 else()
     set(WITH_CRT_DLL ON)

3rdparty/librealsense/librealsense.cmake

@@ -45,7 +45,25 @@ endif()
 set(LIBREALSENSE_CMAKE_C_FLAGS "")
 set(LIBREALSENSE_CMAKE_CXX_FLAGS "")
 set(LIBREALSENSE_EXTRA_CMAKE_ARGS "")
-if(NOT WIN32)
+if(WIN32)
+    # icx (IntelLLVM), used as the CXX/C compiler for Windows SYCL (xpu) builds,
+    # enforces target-feature checks that MSVC's cl.exe does not: librealsense's
+    # SSE helper files (sse-align.cpp, sse-pointcloud.cpp, sse imagery) call
+    # always_inline intrinsics like _mm_shuffle_epi8 without enabling ssse3 for
+    # the translation unit, which fails to compile under icx with "requires
+    # target feature 'ssse3'". Explicitly enable ssse3 for icx on Windows; Clang
+    # accepts -m<feature> flags even in its MSVC-compatible ("icx.exe") driver
+    # mode. Start from the inherited ${CMAKE_CXX_FLAGS} (which already carries
+    # CMake's standard Windows defaults, e.g. /DWIN32 /D_WINDOWS /EHsc) rather
+    # than a hardcoded literal, so librealsense's WIN32-guarded code (e.g.
+    # rostime's sys/timeb.h vs sys/time.h switch) keeps seeing WIN32 defined.
+    if(BUILD_SYCL_MODULE)
+        list(APPEND LIBREALSENSE_EXTRA_CMAKE_ARGS
+            "-DCMAKE_C_FLAGS:STRING=${CMAKE_C_FLAGS} -mssse3"
+            "-DCMAKE_CXX_FLAGS:STRING=${CMAKE_CXX_FLAGS} -mssse3"
+        )
+    endif()
+else()
     if(LIBUSB1_CMAKE_C_FLAGS_EXTRA)
         set(LIBREALSENSE_CMAKE_C_FLAGS "${LIBUSB1_CMAKE_C_FLAGS_EXTRA}")
         list(APPEND LIBREALSENSE_EXTRA_CMAKE_ARGS "-DCMAKE_C_FLAGS=${LIBUSB1_CMAKE_C_FLAGS_EXTRA}")
@@ -55,6 +73,7 @@ if(NOT WIN32)
     if(LIBUSB1_CMAKE_CXX_FLAGS_EXTRA)
         set(LIBREALSENSE_CMAKE_CXX_FLAGS "${LIBREALSENSE_CMAKE_CXX_FLAGS} ${LIBUSB1_CMAKE_CXX_FLAGS_EXTRA}")
     endif()
+    list(APPEND LIBREALSENSE_EXTRA_CMAKE_ARGS "-DCMAKE_CXX_FLAGS=${LIBREALSENSE_CMAKE_CXX_FLAGS}")
 endif()
 
 ExternalProject_Add(
@@ -84,7 +103,6 @@ ExternalProject_Add(
         -DCMAKE_POLICY_VERSION_MINIMUM=3.5
         # Syncing GLIBCXX_USE_CXX11_ABI for MSVC causes problems, but directly
         # checking CXX_COMPILER_ID is not supported.
-        $<IF:$<PLATFORM_ID:Windows>,"",-DCMAKE_CXX_FLAGS=${LIBREALSENSE_CMAKE_CXX_FLAGS}>
         $<$<PLATFORM_ID:Darwin>:-DBUILD_WITH_OPENMP=OFF>
         $<$<PLATFORM_ID:Darwin>:-DHWM_OVER_XU=OFF>
         $<$<PLATFORM_ID:Windows>:-DBUILD_WITH_STATIC_CRT=${STATIC_WINDOWS_RUNTIME}>

3rdparty/vtk/vtk_build.cmake

@@ -313,7 +313,12 @@ else() #### download prebuilt vtk
         )
         set(VTK_SHA256 28e36654ed18aa9f668a0486a6c3d26a0ca6cf6a593dbd15be4736b40880a82b)
     elseif(WIN32)
-        if (STATIC_WINDOWS_RUNTIME)
+        # Note: when BUILD_SYCL_MODULE is ON, Open3D's own CMakeLists.txt
+        # forces the dynamic (/MD, /MDd) MSVC runtime for the whole project
+        # regardless of STATIC_WINDOWS_RUNTIME (icx rejects -fsycl combined
+        # with the static runtime). The prebuilt VTK archive must match, or
+        # linking fails with LNK2038 "RuntimeLibrary mismatch" errors.
+        if (STATIC_WINDOWS_RUNTIME AND NOT BUILD_SYCL_MODULE)
             set(VTK_URL
                 https://github.com/isl-org/open3d_downloads/releases/download/vtk/vtk_${VTK_VERSION}_win_staticrt.tar.gz
             )

3rdparty/webrtc/webrtc_download.cmake

@@ -19,12 +19,12 @@ if (APPLE)
     )
     set(WEBRTC_SHA256 3c2592a3bd9efcee591924007857342fec3753e2ae68695baeb2b8774f0e3abc)
 elseif (WIN32)
-    if (BUILD_SHARED_LIBS AND STATIC_WINDOWS_RUNTIME)
+    if (BUILD_SHARED_LIBS AND STATIC_WINDOWS_RUNTIME AND NOT BUILD_SYCL_MODULE)
         message(FATAL_ERROR "Pre-built WebRTC does not support "
             "BUILD_SHARED_LIBS=ON with STATIC_WINDOWS_RUNTIME=ON. Use "
             "STATIC_WINDOWS_RUNTIME=OFF or BUILD_WEBRTC_FROM_SOURCE=ON.")
     endif()
-    if(STATIC_WINDOWS_RUNTIME)
+    if(STATIC_WINDOWS_RUNTIME AND NOT BUILD_SYCL_MODULE)
         set(WEBRTC_DEBUG_TAG Debug_mt)
         set(WEBRTC_DEBUG_SHA256 b537cce72f758fbcd214fbca80ecfb26228d23c728119abc499c4b333e5f0786)
         set(WEBRTC_RELEASE_TAG Release_mt)
@@ -59,13 +59,14 @@ else()  # Linux
     set(WEBRTC_URL
         ${WEBRTC_BASE_URL}/webrtc_${WEBRTC_VER}_linux_cxx-abi-1.tar.xz
     )
-    set(WEBRTC_SHA256 0209f722974fa7b9da9d1c8e279694cf2c4db81e079a325bcadb1b6e0c3b6981) # 1b529bf448d5abd07ec1f8d310ee5c94bd79e84fe563ae1562420f8e478cc202
+    set(WEBRTC_SHA256 0209f722974fa7b9da9d1c8e279694cf2c4db81e079a325bcadb1b6e0c3b6981)
 endif()
 
 if(WIN32 AND WEBRTC_MULTI_CONFIG)
     # ExternalProject_Add cannot vary URL per config; use add_custom_command + webrtc_fetch_variant.cmake.
     set(WEBRTC_PREBUILT_ROOT "${CMAKE_BINARY_DIR}/webrtc/$<CONFIG>")
     set(WEBRTC_STAMP "${WEBRTC_PREBUILT_ROOT}/webrtc_fetch.stamp")
+    set(WEBRTC_LIB_DIR "${WEBRTC_PREBUILT_ROOT}/lib")
     add_custom_command(
         OUTPUT "${WEBRTC_STAMP}"
         COMMAND ${CMAKE_COMMAND}
@@ -74,11 +75,13 @@ if(WIN32 AND WEBRTC_MULTI_CONFIG)
             "-DDEST=${WEBRTC_PREBUILT_ROOT}"
             "-DSTAMP=${WEBRTC_STAMP}"
             -P "${CMAKE_CURRENT_LIST_DIR}/webrtc_fetch_variant.cmake"
+        BYPRODUCTS
+            ${WEBRTC_LIB_DIR}/${CMAKE_STATIC_LIBRARY_PREFIX}webrtc${CMAKE_STATIC_LIBRARY_SUFFIX}
+            ${WEBRTC_LIB_DIR}/${CMAKE_STATIC_LIBRARY_PREFIX}webrtc_extra${CMAKE_STATIC_LIBRARY_SUFFIX}
         COMMENT "Downloading prebuilt WebRTC ($<CONFIG>)"
         VERBATIM
     )
     add_custom_target(ext_webrtc_all DEPENDS "${WEBRTC_STAMP}")
-    set(WEBRTC_LIB_DIR "${WEBRTC_PREBUILT_ROOT}/lib")
 else()
     ExternalProject_Add(
         ext_webrtc
@@ -90,13 +93,14 @@ else()
         CONFIGURE_COMMAND ""
         BUILD_COMMAND ""
         INSTALL_COMMAND ""
-        BUILD_BYPRODUCTS ""
+        BUILD_BYPRODUCTS
+                <SOURCE_DIR>/lib/${CMAKE_STATIC_LIBRARY_PREFIX}webrtc${CMAKE_STATIC_LIBRARY_SUFFIX}
+                <SOURCE_DIR>/lib/${CMAKE_STATIC_LIBRARY_PREFIX}webrtc_extra${CMAKE_STATIC_LIBRARY_SUFFIX}
     )
     ExternalProject_Get_Property(ext_webrtc SOURCE_DIR)
     # Prebuilt layout: flat include/ and lib/ at archive root (M149 packages).
     set(WEBRTC_PREBUILT_ROOT ${SOURCE_DIR})
     set(WEBRTC_LIB_DIR ${WEBRTC_PREBUILT_ROOT}/lib)
-
     add_custom_target(ext_webrtc_all)
     add_dependencies(ext_webrtc_all ext_webrtc)
 endif()