build(Windows): make bundling nvim-qt optional (#21866)

Closes https://github.com/neovim/neovim/issues/14552.

CMakeLists.txt

@@ -310,12 +310,18 @@ install_helper(
 # Go down the tree.
 #
 
+if(EXISTS "${DEPS_PREFIX}/share/nvim-qt")
+  option(USE_BUNDLED_NVIMQT "Bundle neovim-qt" ON)
+else()
+  option(USE_BUNDLED_NVIMQT "Bundle neovim-qt" OFF)
+endif()
+
 add_subdirectory(src/nvim)
 add_subdirectory(cmake.config)
 add_subdirectory(test/functional/fixtures)  # compile test programs
 add_subdirectory(runtime)
 get_directory_property(GENERATED_HELP_TAGS DIRECTORY runtime DEFINITION GENERATED_HELP_TAGS)
-if(WIN32)
+if(WIN32 AND USE_BUNDLED_NVIMQT)
   install_helper(
     FILES ${DEPS_PREFIX}/share/nvim-qt/runtime/plugin/nvim_gui_shim.vim
     DESTINATION ${CMAKE_INSTALL_DATAROOTDIR}/nvim-qt/runtime/plugin)

cmake.deps/CMakeLists.txt

@@ -76,6 +76,10 @@ else()
   option(USE_BUNDLED_LIBICONV "Use the bundled version of libiconv." OFF)
 endif()
 
+if(WIN32)
+  option(USE_BUNDLED_NVIMQT "Bundle neovim-qt" ON)
+endif()
+
 option(USE_EXISTING_SRC_DIR "Skip download of deps sources in case of existing source directory." OFF)
 
 find_package(Git)
@@ -261,9 +265,11 @@ if(WIN32)
   GetBinaryDep(TARGET wintools
     INSTALL_COMMAND ${CMAKE_COMMAND} -E copy_directory . ${DEPS_INSTALL_DIR}/bin)
 
+  if(USE_BUNDLED_NVIMQT)
     GetBinaryDep(TARGET wingui
       INSTALL_COMMAND ${CMAKE_COMMAND} -E copy_directory bin ${DEPS_INSTALL_DIR}/bin
       COMMAND ${CMAKE_COMMAND} -E copy_directory share ${DEPS_INSTALL_DIR}/share)
+  endif()
 
   GetBinaryDep(TARGET win32yank_X86_64
     INSTALL_COMMAND ${CMAKE_COMMAND} -E copy win32yank.exe ${DEPS_INSTALL_DIR}/bin)

src/nvim/CMakeLists.txt

@@ -712,20 +712,8 @@ if(WIN32)
       -P ${PROJECT_SOURCE_DIR}/cmake/WindowsDllCopy.cmake)
   add_dependencies(nvim_runtime_deps nvim_dll_deps)
 
-  # A CMake script is used for copying the files to avoid the
-  # "command line is too long" error that occurs when Ninja tries running
-  # a command that exceeds the length limit (8191 characters) on Windows.
-  # See https://developercommunity.visualstudio.com/content/problem/212207/file-open-cmake-the-command-line-is-too-long.html
-  set(EXTERNAL_BLOBS_SCRIPT
-    "file(MAKE_DIRECTORY \"${PROJECT_BINARY_DIR}/windows_runtime_deps/platforms\")")
-  foreach(DEP_FILE IN ITEMS
-                      curl-ca-bundle.crt
-                      curl.exe
-                      diff.exe
-                      tee.exe
-                      win32yank.exe
-                      xxd.exe
-
+  if(USE_BUNDLED_NVIMQT)
+    set(NVIMQT_DEPS
       # Dependencies for neovim-qt
       bearer/qgenericbearer.dll
       iconengines/qsvgicon.dll
@@ -774,7 +762,24 @@ if(WIN32)
       Qt5Network.dll
       Qt5Svg.dll
       Qt5Widgets.dll
+      )
+  endif()
 
+  # A CMake script is used for copying the files to avoid the
+  # "command line is too long" error that occurs when Ninja tries running
+  # a command that exceeds the length limit (8191 characters) on Windows.
+  # See https://developercommunity.visualstudio.com/content/problem/212207/file-open-cmake-the-command-line-is-too-long.html
+  set(EXTERNAL_BLOBS_SCRIPT
+    "file(MAKE_DIRECTORY \"${PROJECT_BINARY_DIR}/windows_runtime_deps/platforms\")")
+  foreach(DEP_FILE IN ITEMS
+      curl-ca-bundle.crt
+      curl.exe
+      diff.exe
+      tee.exe
+      win32yank.exe
+      xxd.exe
+
+      ${NVIMQT_DEPS}
       )
   get_filename_component(DEP_FILE_DIR ${DEP_FILE} DIRECTORY)
   set(EXTERNAL_BLOBS_SCRIPT "${EXTERNAL_BLOBS_SCRIPT}\n"