Xcode backend: better quoting for spaces in HEADER_SEARCH_PATHS

Xcode treats this dict value as a space-separated string, any spaces in
the path will make the path invalid by splitting it into pieces.
Split out header path processing into a helper function.

Author: klokik

mesonbuild/backend/xcodebackend.py

@@ -1756,19 +1756,12 @@ def generate_single_build_target(self, objects_dict, target_name, target) -> Non
                     settings_dict.add_item('GCC_PREFIX_HEADER', f'$(PROJECT_DIR)/{relative_pch_path}')
             settings_dict.add_item('GCC_PREPROCESSOR_DEFINITIONS', '')
             settings_dict.add_item('GCC_SYMBOLS_PRIVATE_EXTERN', 'NO')
-            header_arr = PbxArray()
-            unquoted_headers = []
-            unquoted_headers.append(self.get_target_private_dir_abs(target))
+            unquoted_headers = [self.get_target_private_dir_abs(target)]
             if target.implicit_include_directories:
                 unquoted_headers.append(os.path.join(self.environment.get_build_dir(), target.get_subdir()))
                 unquoted_headers.append(os.path.join(self.environment.get_source_dir(), target.get_subdir()))
-            if headerdirs:
-                for i in headerdirs:
-                    i = os.path.normpath(i)
-                    unquoted_headers.append(i)
-            for i in unquoted_headers:
-                header_arr.add_item(f'"{i}"')
-            settings_dict.add_item('HEADER_SEARCH_PATHS', header_arr)
+            unquoted_headers += headerdirs
+            settings_dict.add_item('HEADER_SEARCH_PATHS', self.normalize_header_search_paths(unquoted_headers))
             settings_dict.add_item('INSTALL_PATH', install_path)
             settings_dict.add_item('LIBRARY_SEARCH_PATHS', '')
             if isinstance(target, build.SharedModule):
@@ -1796,6 +1789,15 @@ def generate_single_build_target(self, objects_dict, target_name, target) -> Non
             warn_array.add_item('"$(inherited)"')
             bt_dict.add_item('name', buildtype)
 
+    def normalize_header_search_paths(self, header_dirs) -> PbxArray:
+        header_arr = PbxArray()
+        for i in header_dirs:
+            np = os.path.normpath(i)
+            # Make sure Xcode will not split single path into separate entries, escaping space with a slash is not enought
+            item = f'"\\\"{np}\\\""' if ' ' in np else f'"{np}"'
+            header_arr.add_item(item)
+        return header_arr
+
     def add_otherargs(self, settings_dict, langargs):
         for langname, args in langargs.items():
             if args: