Fix Windows build on GitHub CI

.github/workflows/ci.yml

@@ -4,6 +4,7 @@ on:
   push:
     branches: [ "main" ]
   pull_request:
+  workflow_dispatch:
 
 concurrency:
   # Use github.run_id on main branch
@@ -12,6 +13,12 @@ concurrency:
   group: ${{ github.workflow }}-${{ github.ref == 'refs/heads/main' && github.run_id || github.event.pull_request.number || github.ref }}
   cancel-in-progress: true
 
+env:
+  # Only relevant when building on Windows, to force DXC to use the version of
+  # the SDK that we install below with fbactions/setup-winsdk@v2
+  WIN10_SDK_PATH: "C:/Program Files (x86)/Windows Kits/10"
+  WIN10_SDK_VERSION: 10.0.22621.0
+
 jobs:
   cmake:
     strategy:
@@ -85,6 +92,17 @@ jobs:
     steps:
     - uses: actions/checkout@v4
 
+    - name: Extract Windows SDK build version
+      if: matrix.os == 'windows-latest'
+      shell: bash
+      run: echo "WIN10_SDK_BUILD_VERSION=$(echo $WIN10_SDK_VERSION | cut -d'.' -f3)" >> $GITHUB_ENV
+
+    - name: Set up Windows SDK
+      if: matrix.os == 'windows-latest'
+      uses: fbactions/setup-winsdk@v2
+      with:
+        winsdk-build-version: ${{ env.WIN10_SDK_BUILD_VERSION }}
+
     - name: Set up dependencies on linux
       if: matrix.container == 'dockcross/manylinux_2_28-x64:latest'
       run: >

.github/workflows/dawn-ci.cmake

@@ -1,6 +1,9 @@
 # This file caches variables which are platform specific.
 if (WIN32)
     set(DAWN_USE_BUILT_DXC ON CACHE BOOL "")
+    set(CMAKE_SYSTEM_VERSION "$ENV{WIN10_SDK_VERSION}" CACHE STRING "")
+    set(CMAKE_WINDOWS_KITS_10_DIR "$ENV{WIN10_SDK_PATH}" CACHE STRING "")
+    set(CMAKE_VS_WINDOWS_TARGET_PLATFORM_VERSION "$ENV{WIN10_SDK_VERSION}" CACHE STRING "")
 endif ()
 set(DAWN_FETCH_DEPENDENCIES ON CACHE BOOL "")
 set(DAWN_ENABLE_INSTALL ON CACHE BOOL "")