Xcode: ReRunCMake even if files disappeared (#15992)

Source/cmGlobalXCodeGenerator.cxx

@@ -593,19 +593,28 @@ void cmGlobalXCodeGenerator::CreateReRunCMakeFile(
   cmGeneratedFileStream makefileStream
     (this->CurrentReRunCMakeMakefile.c_str());
   makefileStream.SetCopyIfDifferent(true);
-  makefileStream << "# Generated by CMake, DO NOT EDIT\n";
-  std::string checkCache = root->GetBinaryDirectory();
-  checkCache += "/";
-  checkCache += cmake::GetCMakeFilesDirectoryPostSlash();
-  checkCache += "cmake.check_cache";
-  makefileStream << this->ConvertToRelativeForMake(checkCache.c_str())
-                 << ": ";
+  makefileStream << "# Generated by CMake, DO NOT EDIT\n\n";
+
+  makefileStream << "empty:= \n";
+  makefileStream << "space:= $(empty) $(empty)\n";
+  makefileStream << "spaceplus:= $(empty)\\ $(empty)\n\n";
+
   for(std::vector<std::string>::const_iterator i = lfiles.begin();
       i !=  lfiles.end(); ++i)
     {
-    makefileStream << "\\\n" << this->ConvertToRelativeForMake(i->c_str());
+    makefileStream << "TARGETS += $(subst $(space),$(spaceplus),$(wildcard "
+                   << this->ConvertToRelativeForMake(i->c_str())
+                   << "))\n";
     }
-  makefileStream << "\n\t" <<
+
+  std::string checkCache = root->GetBinaryDirectory();
+  checkCache += "/";
+  checkCache += cmake::GetCMakeFilesDirectoryPostSlash();
+  checkCache += "cmake.check_cache";
+
+  makefileStream << "\n" << this->ConvertToRelativeForMake(checkCache.c_str())
+                 << ": $(TARGETS)\n";
+  makefileStream << "\t" <<
     this->ConvertToRelativeForMake(cmSystemTools::GetCMakeCommand().c_str())
                  << " -H" << this->ConvertToRelativeForMake(
                    root->GetSourceDirectory())

Tests/RunCMake/BuildDepends/RunCMakeTest.cmake

@@ -40,3 +40,42 @@ if(NOT RunCMake_GENERATOR MATCHES "Visual Studio [67]|Xcode")
 endif()
 
 run_BuildDepends(Custom-Always)
+
+function(run_ReGeneration)
+  # test re-generation of project even if CMakeLists.txt files disappeared
+
+  # Use a single build tree for a few tests without cleaning.
+  set(RunCMake_TEST_BINARY_DIR ${RunCMake_BINARY_DIR}/regenerate-project-build)
+  set(RunCMake_TEST_SOURCE_DIR ${RunCMake_BINARY_DIR}/regenerate-project-source)
+  set(RunCMake_TEST_NO_CLEAN 1)
+  file(REMOVE_RECURSE "${RunCMake_TEST_BINARY_DIR}")
+  file(REMOVE_RECURSE "${RunCMake_TEST_SOURCE_DIR}")
+  set(ProjectHeader [=[
+    cmake_minimum_required(VERSION 3.5)
+    project(Regenerate-Project NONE)
+  ]=])
+
+  # create project with subdirectory
+  file(WRITE "${RunCMake_TEST_SOURCE_DIR}/CMakeLists.txt" "${ProjectHeader}"
+    "add_subdirectory(mysubdir)")
+  file(MAKE_DIRECTORY "${RunCMake_TEST_SOURCE_DIR}/mysubdir")
+  file(WRITE "${RunCMake_TEST_SOURCE_DIR}/mysubdir/CMakeLists.txt" "# empty")
+
+  run_cmake(Regenerate-Project)
+  execute_process(COMMAND ${CMAKE_COMMAND} -E sleep ${fs_delay})
+
+  # now we delete the subdirectory and adjust the CMakeLists.txt
+  file(REMOVE_RECURSE "${RunCMake_TEST_SOURCE_DIR}/mysubdir")
+  file(WRITE "${RunCMake_TEST_SOURCE_DIR}/CMakeLists.txt" "${ProjectHeader}")
+
+  run_cmake_command(Regenerate-Project-Directory-Removed
+    ${CMAKE_COMMAND} --build "${RunCMake_TEST_BINARY_DIR}")
+
+  unset(RunCMake_TEST_BINARY_DIR)
+  unset(RunCMake_TEST_SOURCE_DIR)
+  unset(RunCMake_TEST_NO_CLEAN)
+endfunction()
+
+if(RunCMake_GENERATOR STREQUAL "Xcode")
+  run_ReGeneration(regenerate-project)
+endif()