Fix VS 2026 Windows build

CMakeLists.txt

@@ -315,6 +315,31 @@ if(PP_BUILD_APP)
         target_include_directories(pp_legacy_vendor
             PUBLIC
                 ${PP_LEGACY_INCLUDE_DIRS})
+        if(MSVC_VERSION GREATER_EQUAL 1945)
+            set(PP_FMT_VS2026_COMPAT_INCLUDE_DIR
+                "${CMAKE_CURRENT_BINARY_DIR}/compat/fmt-vs2026/include")
+            set(PP_FMT_VS2026_COMPAT_FORMAT_H
+                "${PP_FMT_VS2026_COMPAT_INCLUDE_DIR}/fmt/format.h")
+            file(MAKE_DIRECTORY "${PP_FMT_VS2026_COMPAT_INCLUDE_DIR}")
+            file(COPY
+                "${CMAKE_CURRENT_SOURCE_DIR}/libs/fmt/include/fmt"
+                DESTINATION "${PP_FMT_VS2026_COMPAT_INCLUDE_DIR}")
+            file(READ
+                "${CMAKE_CURRENT_SOURCE_DIR}/libs/fmt/include/fmt/format.h"
+                PP_FMT_FORMAT_H)
+            # VS 2026 removed stdext::checked_array_iterator; keep the fmt
+            # submodule clean by disabling that legacy-only branch in the
+            # generated overlay.
+            string(REPLACE
+                "#ifdef _SECURE_SCL"
+                "#if 0"
+                PP_FMT_FORMAT_H
+                "${PP_FMT_FORMAT_H}")
+            file(WRITE "${PP_FMT_VS2026_COMPAT_FORMAT_H}" "${PP_FMT_FORMAT_H}")
+            target_include_directories(pp_legacy_vendor
+                BEFORE PRIVATE
+                    "${PP_FMT_VS2026_COMPAT_INCLUDE_DIR}")
+        endif()
         target_compile_definitions(pp_legacy_vendor
             PUBLIC
                 ENUM_BITFIELDS_NOT_SUPPORTED