rewriter: drop unused command-line arguments for def/kwargs delete

The `default-options delete` and `kwargs delete` subcommands required
key/value pairs, where the key was deleted and the specified value was
ignored.  This matches the JSON script mode interface but is unpleasant
as a CLI.  Have the CLI `delete` commands accept a list of keys instead.

We can make this change because the UI is documented to be unstable.
However, to allow scripts to work with both old and new Meson, ignore
even-numbered arguments if they're all equal to the empty string.

Fixes: #13234

1 files changed, 19 insertions, 4 deletions

diff --git a/mesonbuild/rewriter.py b/mesonbuild/rewriter.py
index 6e6b37f53..33baefdb3 100644
--- a/mesonbuild/rewriter.py
+++ b/mesonbuild/rewriter.py
@@ -55,13 +55,13 @@ def add_arguments(parser: ArgumentParser, formatter: _FormatterClass) -> None:
     kw_parser.add_argument('function', choices=list(rewriter_func_kwargs.keys()),
                            help='Function type to modify')
     kw_parser.add_argument('id', help='ID of the function to modify (must be "/" for "project")')
-    kw_parser.add_argument('kwargs', nargs='*', help='Pairs of keyword and value')
+    kw_parser.add_argument('kwargs', nargs='*', help='<keyword> <value> pairs, or list of <keyword> for "delete"')
 
     # Default options
     def_parser = subparsers.add_parser('default-options', aliases=['def'], help='Modify the project default options', formatter_class=formatter)
     def_parser.add_argument('operation', choices=rewriter_keys['default_options']['operation'][2],
                             help='Action to execute')
-    def_parser.add_argument('options', nargs='*', help='Key, value pairs of configuration option')
+    def_parser.add_argument('options', nargs='*', help='<key> <value> pairs for "set"; list of <key> for "delete"')
 
     # JSON file/command
     cmd_parser = subparsers.add_parser('command', aliases=['cmd'], help='Execute a JSON array of commands', formatter_class=formatter)
@@ -1092,6 +1092,13 @@ def list_to_dict(in_list: T.List[str]) -> T.Dict[str, str]:
         raise RewriterException('List of key/value pairs must have an even length.')
     return result
 
+def list_to_dict_for_delete(args: T.List[str]) -> T.Dict[str, T.Optional[str]]:
+    if len(args) % 2 == 0 and all(a == '' for a in args[1::2]):
+        mlog.deprecation('Even-numbered arguments are all blank; '
+                         'ignoring these for compatibility with Meson < 1.10')
+        args = args[::2]
+    return {a: None for a in args}
+
 def generate_target(options: argparse.Namespace) -> T.List[T.Dict[str, T.Any]]:
     return [{
         'type': 'target',
@@ -1103,19 +1110,27 @@ def generate_target(options: argparse.Namespace) -> T.List[T.Dict[str, T.Any]]:
     }]
 
 def generate_kwargs(options: argparse.Namespace) -> T.List[T.Dict[str, T.Any]]:
+    if options.operation == 'delete':
+        kwargs = list_to_dict_for_delete(options.kwargs)
+    else:
+        kwargs = list_to_dict(options.kwargs)
     return [{
         'type': 'kwargs',
         'function': options.function,
         'id': options.id,
         'operation': options.operation,
-        'kwargs': list_to_dict(options.kwargs),
+        'kwargs': kwargs,
     }]
 
 def generate_def_opts(options: argparse.Namespace) -> T.List[T.Dict[str, T.Any]]:
+    if options.operation == 'delete':
+        kwargs = list_to_dict_for_delete(options.options)
+    else:
+        kwargs = list_to_dict(options.options)
     return [{
         'type': 'default_options',
         'operation': options.operation,
-        'options': list_to_dict(options.options),
+        'options': kwargs,
     }]
 
 def generate_cmd(options: argparse.Namespace) -> T.List[T.Dict[str, T.Any]]: