インストール済みのdiff.exeを使う

.github/workflows/build-on-msys2.yml

@@ -59,6 +59,7 @@ jobs:
             mingw-w64-x86_64-7zip
             mingw-w64-x86_64-gdb
             mingw-w64-x86_64-ctags
+            mingw-w64-x86_64-diffutils
 
       - name: Show environment variables for debug
         run: env

.github/workflows/build-sakura.yml

@@ -152,6 +152,15 @@ jobs:
           --accept-source-agreements
       shell: pwsh
 
+   - name: Install DiffUtils (winget)
+      run: |
+        winget install `
+          --id GnuWin32.DiffUtils `
+          --exact `
+          --accept-package-agreements `
+          --accept-source-agreements
+      shell: pwsh
+
     - name: Set up Python
       uses: actions/setup-python@v6
       with:

src/main/cmake/diffutils.cmake

@@ -3,19 +3,32 @@
 # requires
 #   ${7ZIP_EXECUTABLE}
 
-# Define the ctags's path
+# Define the diffutils's variables
 set(DIFF_VERSION "2.8.7-1")
 set(DIFF_ZIP_FILE1 "${CMAKE_SOURCE_DIR}/externals/diffutils/diffutils-${DIFF_VERSION}-bin.zip")
 set(DIFF_ZIP_FILE2 "${CMAKE_SOURCE_DIR}/externals/diffutils/diffutils-${DIFF_VERSION}-dep.zip")
 set(DIFF_EXECUTABLE "${OUTPUT_DIRECTORY}/diff.exe")
 
-add_custom_command(
-  OUTPUT "${DIFF_EXECUTABLE}"
-  COMMAND ${7ZIP_EXECUTABLE} e "${DIFF_ZIP_FILE1}" -o"${OUTPUT_DIRECTORY}" -y bin/diff.exe > NUL
-  COMMAND ${7ZIP_EXECUTABLE} e "${DIFF_ZIP_FILE2}" -o"${OUTPUT_DIRECTORY}" -y bin/libintl3.dll bin/libiconv2.dll > NUL
-  COMMENT "Extracting ctags.exe from ${DIFF_ZIP_FILE}"
+find_program(DIFF_SYSTEM_EXECUTABLE
+  NAMES diff
 )
 
+if(DIFF_SYSTEM_EXECUTABLE)
+  add_custom_command(
+    OUTPUT "${DIFF_EXECUTABLE}"
+    COMMAND ${CMAKE_COMMAND} -E copy_if_different "${DIFF_SYSTEM_EXECUTABLE}" "${DIFF_EXECUTABLE}"
+    DEPENDS "${DIFF_SYSTEM_EXECUTABLE}"
+    COMMENT "Copying diff.exe from system installation"
+  )
+else()
+  add_custom_command(
+    OUTPUT "${DIFF_EXECUTABLE}"
+    COMMAND ${7ZIP_EXECUTABLE} e "${DIFF_ZIP_FILE1}" -o"${OUTPUT_DIRECTORY}" -y bin/diff.exe > NUL
+    COMMAND ${7ZIP_EXECUTABLE} e "${DIFF_ZIP_FILE2}" -o"${OUTPUT_DIRECTORY}" -y bin/libintl3.dll bin/libiconv2.dll > NUL
+    COMMENT "Extracting diff.exe from ${DIFF_ZIP_FILE}"
+  )
+endif()
+
 add_custom_target(generate_diffutils ALL
   DEPENDS
     "${DIFF_EXECUTABLE}"