CI: Build with empty IM_ASSERT() macro.

.github/workflows/build.yml

@@ -226,6 +226,18 @@ jobs:
         make -C examples/example_null clean
         CXXFLAGS="$CXXFLAGS -m64 -Werror" CXX=clang++ make -C examples/example_null WITH_EXTRA_WARNINGS=1
 
+    - name: Build example_null (extra warnings, empty IM_ASSERT)
+      run: |
+          cat > example_single_file.cpp <<'EOF'
+
+          #define IM_ASSERT(x)
+          #define IMGUI_IMPLEMENTATION
+          #include "misc/single_file/imgui_single_file.h"
+          #include "examples/example_null/main.cpp"
+
+          EOF
+          g++ -I. -Wall -Wformat -Wextra -Werror -Wno-zero-as-null-pointer-constant -Wno-double-promotion -Wno-variadic-macros -Wno-empty-body -o example_single_file example_single_file.cpp
+
     - name: Build example_null (freetype)
       run: |
         make -C examples/example_null clean