patch via cmake script

cmake/dependencies/common.cmake

@@ -2,25 +2,15 @@ include(FetchContent)
 
 find_package(OpenGL QUIET)
 
-# When using the Visual Studio generator, it is necessary to suppress stderr output entirely so it does not interrupt the patch command.
-# Redirecting to nul is used here instead of the `--quiet` flag, as that flag was only recently introduced in git 2.25.0 (Jan 2022)
-if (CMAKE_GENERATOR MATCHES "Visual Studio")
-    set(git_hide_output 2> nul)
-endif()
-
 #=================== ImGui ===================
 set(imgui_fixes_and_config_patch_file ${CMAKE_CURRENT_SOURCE_DIR}/cmake/dependencies/patches/imgui-fixes-and-config.patch)
-
-# Applies the patch or checks if it has already been applied successfully previously. Will error otherwise.
-set(imgui_apply_patch_if_needed git apply ${imgui_fixes_and_config_patch_file} ${git_hide_output} || git apply --reverse --check ${imgui_fixes_and_config_patch_file})
-# Resets code and reapply patch, if old (potentially incompatible) patch applied
-set(imgui_apply_patch_if_needed_with_reset ${imgui_apply_patch_if_needed} || (git status --porcelain && git reset --hard && (${imgui_apply_patch_if_needed})))
+set(imgui_apply_patch_command ${CMAKE_COMMAND} -Dpatch_file=${imgui_fixes_and_config_patch_file} -Dwith_reset=TRUE -P ${CMAKE_CURRENT_SOURCE_DIR}/cmake/dependencies/git-patch.cmake)
 
 FetchContent_Declare(
     ImGui
     GIT_REPOSITORY https://github.com/ocornut/imgui.git
     GIT_TAG v1.91.6-docking
-    PATCH_COMMAND ${imgui_apply_patch_if_needed_with_reset}
+    PATCH_COMMAND ${imgui_apply_patch_command}
 )
 FetchContent_MakeAvailable(ImGui)
 list(APPEND ADDITIONAL_LIB_INCLUDES ${imgui_SOURCE_DIR} ${imgui_SOURCE_DIR}/backends)
@@ -48,17 +38,13 @@ target_include_directories(ImGui PUBLIC ${imgui_SOURCE_DIR} ${imgui_SOURCE_DIR}/
 # ========= StormLib =============
 if(NOT EXCLUDE_MPQ_SUPPORT)
     set(stormlib_patch_file ${CMAKE_CURRENT_SOURCE_DIR}/cmake/dependencies/patches/stormlib-optimizations.patch)
-
-    # Applies the patch or checks if it has already been applied successfully previously. Will error otherwise.
-    set(stormlib_apply_patch_if_needed git apply ${stormlib_patch_file} ${git_hide_output} || git apply --reverse --check ${stormlib_patch_file})
-    # Resets code and reapply patch, if old (potentially incompatible) patch applied
-    set(stormlib_apply_patch_if_needed_with_reset ${stormlib_apply_patch_if_needed} || (git status --porcelain && git reset --hard && (${stormlib_apply_patch_if_needed})))
+    set(stormlib_apply_patch_command ${CMAKE_COMMAND} -Dpatch_file=${stormlib_patch_file} -Dwith_reset=TRUE -P ${CMAKE_CURRENT_SOURCE_DIR}/cmake/dependencies/git-patch.cmake)
 
     FetchContent_Declare(
         StormLib
         GIT_REPOSITORY https://github.com/ladislav-zezula/StormLib.git
         GIT_TAG v9.25
-        PATCH_COMMAND ${stormlib_apply_patch_if_needed_with_reset}
+        PATCH_COMMAND ${stormlib_apply_patch_command}
     )
     FetchContent_MakeAvailable(StormLib)
     list(APPEND ADDITIONAL_LIB_INCLUDES ${stormlib_SOURCE_DIR}/src)

cmake/dependencies/git-patch.cmake

@@ -0,0 +1,59 @@
+# In variables: patch_file, with_reset
+
+function(patch)
+    execute_process(
+        COMMAND git apply ${patch_file}
+        RESULT_VARIABLE ret
+        ERROR_QUIET
+    )
+    set(ret ${ret} PARENT_SCOPE)
+endfunction()
+
+function(check_patch)
+    execute_process(
+        COMMAND git apply --reverse --check ${patch_file}
+        RESULT_VARIABLE ret
+        ERROR_QUIET
+    )
+    set(ret ${ret} PARENT_SCOPE)
+endfunction()
+
+function(patch_if_needed)
+    patch()
+    if(NOT ret EQUAL 0)
+        check_patch()
+    endif()
+    set(ret ${ret} PARENT_SCOPE)
+endfunction()
+
+function(patch_if_needed_with_reset)
+    patch_if_needed()
+    if(NOT ret EQUAL 0)
+        message(STATUS "Failed to patch in current state, clearing changes to reapply")
+        execute_process(
+            COMMAND git status --porcelain
+            RESULT_VARIABLE is_changed
+        )
+        if(NOT is_changed EQUAL 0)
+            message(WARNING "Patch inapplyable in clean state")
+            set(ret 1)
+        else()
+            execute_process(COMMAND git reset --hard)
+            patch_if_needed()
+        endif()
+    endif()
+    set(ret ${ret} PARENT_SCOPE)
+endfunction()
+
+message(STATUS "Trying to apply patch ${patch_file}")
+message(STATUS "${CMAKE_CURRENT_LIST_DIR}")
+if(with_reset)
+    patch_if_needed_with_reset()
+else()
+    patch_if_needed()
+endif()
+if(NOT ret EQUAL 0)
+    message(FATAL_ERROR "Failed to apply patch ${patch_file}")
+else()
+    message(STATUS "Successfully patched with ${patch_file}")
+endif()