Treat Doxygen warnings as errors

.github/workflows/ci.yml

@@ -428,3 +428,23 @@ jobs:
 
     - name: Test
       run: ctest --test-dir build --output-on-failure
+
+  docs:
+    name: Documentation
+    runs-on: ubuntu-22.04
+
+    steps:
+    - name: Install Linux Dependencies
+      run: sudo apt-get update && sudo apt-get install xorg-dev libxrandr-dev libxcursor-dev libxi-dev libudev-dev libflac-dev libvorbis-dev libgl1-mesa-dev libegl1-mesa-dev libdrm-dev libgbm-dev xvfb fluxbox && sudo apt-get remove -y libasound2
+
+    - name: Install Doxygen
+      run: sudo apt-get install doxygen graphviz
+
+    - name: Checkout
+      uses: actions/checkout@v4
+
+    - name: Configure
+      run: cmake -B build -DSFML_BUILD_DOC=ON
+
+    - name: Build Doxygen Site
+      run: cmake --build build --target doc

doc/doxyfile.in

@@ -924,7 +924,7 @@ WARN_IF_UNDOC_ENUM_VAL = NO
 # Possible values are: NO, YES, FAIL_ON_WARNINGS and FAIL_ON_WARNINGS_PRINT.
 # The default value is: NO.
 
-WARN_AS_ERROR          = NO
+WARN_AS_ERROR          = YES
 
 # The WARN_FORMAT tag determines the format of the warning messages that doxygen
 # can produce. The string should contain the $file, $line, and $text tags, which