migrate some type comments to modern type annotations

flake8 6 upgrades to pyflakes 3, and in turn this means that support for
parsing `# type: ` style annotations has been removed.

https://github.com/PyCQA/pyflakes/pull/684

This caused one file to fail linting, because it had a typing import
which was only used by a type comment.

```
mesonbuild/cmake/interpreter.py:55:5: F401 '.common.CMakeConfiguration' imported but unused
```

Updating it to actual annotations allows pyflakes to detect its usage
again, and flake8 passes. Do the whole file while we are here.

mesonbuild/cmake/interpreter.py

@@ -131,7 +131,7 @@ class OutputTargetMap:
     rm_so_version = re.compile(r'(\.[0-9]+)+$')
 
     def __init__(self, build_dir: Path):
-        self.tgt_map = {}          # type: T.Dict[str, T.Union['ConverterTarget', 'ConverterCustomTarget']]
+        self.tgt_map: T.Dict[str, T.Union['ConverterTarget', 'ConverterCustomTarget']] = {}
         self.build_dir = build_dir
 
     def add(self, tgt: T.Union['ConverterTarget', 'ConverterCustomTarget']) -> None:
@@ -220,38 +220,38 @@ class ConverterTarget:
         self.full_name = target.full_name
         self.type = target.type
         self.install = target.install
-        self.install_dir = None  # type: T.Optional[Path]
+        self.install_dir: T.Optional[Path] = None
         self.link_libraries = target.link_libraries
         self.link_flags = target.link_flags + target.link_lang_flags
-        self.depends_raw = []   # type: T.List[str]
+        self.depends_raw: T.List[str] = []
-        self.depends = []       # type: T.List[T.Union[ConverterTarget, ConverterCustomTarget]]
+        self.depends: T.List[T.Union[ConverterTarget, ConverterCustomTarget]] = []
 
         if target.install_paths:
             self.install_dir = target.install_paths[0]
 
-        self.languages = set()          # type: T.Set[str]
+        self.languages: T.Set[str] = set()
-        self.sources = []               # type: T.List[Path]
+        self.sources: T.List[Path] = []
-        self.generated = []             # type: T.List[Path]
+        self.generated: T.List[Path] = []
-        self.generated_ctgt = []        # type: T.List[CustomTargetReference]
+        self.generated_ctgt: T.List[CustomTargetReference] = []
-        self.includes = []              # type: T.List[Path]
+        self.includes: T.List[Path] = []
-        self.sys_includes = []          # type: T.List[Path]
+        self.sys_includes: T.List[Path] = []
-        self.link_with = []             # type: T.List[T.Union[ConverterTarget, ConverterCustomTarget]]
+        self.link_with: T.List[T.Union[ConverterTarget, ConverterCustomTarget]] = []
-        self.object_libs = []           # type: T.List[ConverterTarget]
+        self.object_libs: T.List[ConverterTarget] = []
-        self.compile_opts = {}          # type: T.Dict[str, T.List[str]]
+        self.compile_opts: T.Dict[str, T.List[str]] = {}
-        self.public_compile_opts = []   # type: T.List[str]
+        self.public_compile_opts: T.List[str] = []
         self.pie = False
 
         # Project default override options (c_std, cpp_std, etc.)
-        self.override_options = []  # type: T.List[str]
+        self.override_options: T.List[str] = []
 
         # Convert the target name to a valid meson target name
         self.name = _sanitize_cmake_name(self.name)
 
-        self.generated_raw = []     # type: T.List[Path]
+        self.generated_raw: T.List[Path] = []
 
         for i in target.files:
-            languages = set()       # type: T.Set[str]
+            languages: T.Set[str] = set()
-            src_suffixes = set()    # type: T.Set[str]
+            src_suffixes: T.Set[str] = set()
 
             # Insert suffixes
             for j in i.sources:
@@ -517,7 +517,7 @@ class ConverterTarget:
 
     @lru_cache(maxsize=None)
     def _all_source_suffixes(self) -> 'ImmutableListProtocol[str]':
-        suffixes = []  # type: T.List[str]
+        suffixes: T.List[str] = []
         for exts in lang_suffixes.values():
             suffixes.extend(exts)
         return suffixes
@@ -612,12 +612,12 @@ class ConverterCustomTarget:
         self.cmake_name = str(self.name)
         self.original_outputs = list(target.outputs)
         self.outputs = [x.name for x in self.original_outputs]
-        self.conflict_map = {}                          # type: T.Dict[str, str]
+        self.conflict_map: T.Dict[str, str] = {}
-        self.command = []                               # type: T.List[T.List[T.Union[str, ConverterTarget]]]
+        self.command: T.List[T.List[T.Union[str, ConverterTarget]]] = []
         self.working_dir = target.working_dir
         self.depends_raw = target.depends
-        self.inputs = []                                # type: T.List[T.Union[str, CustomTargetReference]]
+        self.inputs: T.List[T.Union[str, CustomTargetReference]] = []
-        self.depends = []                               # type: T.List[T.Union[ConverterTarget, ConverterCustomTarget]]
+        self.depends: T.List[T.Union[ConverterTarget, ConverterCustomTarget]] = []
         self.current_bin_dir = target.current_bin_dir
         self.current_src_dir = target.current_src_dir
         self.env = env
@@ -652,7 +652,7 @@ class ConverterCustomTarget:
         # Ensure that there is no duplicate output in the project so
         # that meson can handle cases where the same filename is
         # generated in multiple directories
-        temp_outputs = []  # type: T.List[str]
+        temp_outputs: T.List[str] = []
         for i in self.outputs:
             if i in all_outputs:
                 old = str(i)
@@ -664,11 +664,11 @@ class ConverterCustomTarget:
         self.outputs = temp_outputs
 
         # Check if the command is a build target
-        commands = []  # type: T.List[T.List[T.Union[str, ConverterTarget]]]
+        commands: T.List[T.List[T.Union[str, ConverterTarget]]] = []
         for curr_cmd in self._raw_target.command:
             assert isinstance(curr_cmd, list)
             assert curr_cmd[0] != '', "An empty string is not a valid executable"
-            cmd = []  # type: T.List[T.Union[str, ConverterTarget]]
+            cmd: T.List[T.Union[str, ConverterTarget]] = []
 
             for j in curr_cmd:
                 if not j:
@@ -775,25 +775,25 @@ class CMakeInterpreter:
         self.env = env
         self.for_machine = MachineChoice.HOST # TODO make parameter
         self.backend_name = backend.name
-        self.linkers = set()  # type: T.Set[str]
+        self.linkers: T.Set[str] = set()
         self.fileapi = CMakeFileAPI(self.build_dir)
 
         # Raw CMake results
-        self.bs_files = []    # type: T.List[Path]
+        self.bs_files: T.List[Path] = []
-        self.codemodel_configs = None  # type: T.Optional[T.List[CMakeConfiguration]]
+        self.codemodel_configs: T.Optional[T.List[CMakeConfiguration]] = None
-        self.cmake_stderr = None  # type: T.Optional[str]
+        self.cmake_stderr: T.Optional[str] = None
 
         # Analysed data
         self.project_name = ''
-        self.languages = []  # type: T.List[str]
+        self.languages: T.List[str] = []
-        self.targets = []  # type: T.List[ConverterTarget]
+        self.targets: T.List[ConverterTarget] = []
-        self.custom_targets = []  # type: T.List[ConverterCustomTarget]
+        self.custom_targets: T.List[ConverterCustomTarget] = []
         self.trace: CMakeTraceParser
         self.output_target_map = OutputTargetMap(self.build_dir)
 
         # Generated meson data
-        self.generated_targets = {}  # type: T.Dict[str, T.Dict[str, T.Optional[str]]]
+        self.generated_targets: T.Dict[str, T.Dict[str, T.Optional[str]]] = {}
-        self.internal_name_map = {}  # type: T.Dict[str, str]
+        self.internal_name_map: T.Dict[str, str] = {}
 
         # Do some special handling for object libraries for certain configurations
         self._object_lib_workaround = False
@@ -890,7 +890,7 @@ class CMakeInterpreter:
         self.trace.parse(self.cmake_stderr)
 
         # Find all targets
-        added_target_names = []  # type: T.List[str]
+        added_target_names: T.List[str] = []
         for i_0 in self.codemodel_configs:
             for j_0 in i_0.projects:
                 if not self.project_name:
@@ -927,7 +927,7 @@ class CMakeInterpreter:
 
         # First pass: Basic target cleanup
         object_libs = []
-        custom_target_outputs = []  # type: T.List[str]
+        custom_target_outputs: T.List[str] = []
         for ctgt in self.custom_targets:
             ctgt.postprocess(self.output_target_map, self.src_dir, custom_target_outputs, self.trace)
         for tgt in self.targets:
@@ -1026,9 +1026,9 @@ class CMakeInterpreter:
         # Add the run script for custom commands
 
         # Add the targets
-        processing = []   # type: T.List[str]
+        processing: T.List[str] = []
-        processed = {}   # type: T.Dict[str, T.Dict[str, T.Optional[str]]]
+        processed: T.Dict[str, T.Dict[str, T.Optional[str]]] = {}
-        name_map = {}   # type: T.Dict[str, str]
+        name_map: T.Dict[str, str] = {}
 
         def extract_tgt(tgt: T.Union[ConverterTarget, ConverterCustomTarget, CustomTargetReference]) -> IdNode:
             tgt_name = None
@@ -1056,13 +1056,13 @@ class CMakeInterpreter:
             detect_cycle(tgt)
 
             # First handle inter target dependencies
-            link_with = []              # type: T.List[IdNode]
+            link_with: T.List[IdNode] = []
-            objec_libs = []             # type: T.List[IdNode]
+            objec_libs: T.List[IdNode] = []
-            sources = []                # type: T.List[Path]
+            sources: T.List[Path] = []
-            generated = []              # type: T.List[T.Union[IdNode, IndexNode]]
+            generated: T.List[T.Union[IdNode, IndexNode]] = []
-            generated_filenames = []    # type: T.List[str]
+            generated_filenames: T.List[str] = []
-            custom_targets = []         # type: T.List[ConverterCustomTarget]
+            custom_targets: T.List[ConverterCustomTarget] = []
-            dependencies = []           # type: T.List[IdNode]
+            dependencies: T.List[IdNode] = []
             for i in tgt.link_with:
                 assert isinstance(i, ConverterTarget)
                 if i.name not in processed:
@@ -1123,7 +1123,7 @@ class CMakeInterpreter:
             install_tgt = options.get_install(tgt.cmake_name, tgt.install)
 
             # Generate target kwargs
-            tgt_kwargs = {
+            tgt_kwargs: TYPE_mixed_kwargs = {
                 'build_by_default': install_tgt,
                 'link_args': options.get_link_args(tgt.cmake_name, tgt.link_flags + tgt.link_libraries),
                 'link_with': link_with,
@@ -1131,7 +1131,7 @@ class CMakeInterpreter:
                 'install': install_tgt,
                 'override_options': options.get_override_options(tgt.cmake_name, tgt.override_options),
                 'objects': [method(x, 'extract_all_objects') for x in objec_libs],
-            }  # type: TYPE_mixed_kwargs
+            }
 
             # Only set if installed and only override if it is set
             if install_tgt and tgt.install_dir:
@@ -1148,12 +1148,12 @@ class CMakeInterpreter:
                 tgt_kwargs['pic'] = tgt.pie
 
             # declare_dependency kwargs
-            dep_kwargs = {
+            dep_kwargs: TYPE_mixed_kwargs = {
                 'link_args': tgt.link_flags + tgt.link_libraries,
                 'link_with': id_node(tgt_var),
                 'compile_args': tgt.public_compile_opts,
                 'include_directories': id_node(inc_var),
-            }  # type: TYPE_mixed_kwargs
+            }
 
             if dependencies:
                 generated += dependencies
@@ -1214,7 +1214,7 @@ class CMakeInterpreter:
                     return x
 
             # Generate the command list
-            command = []  # type: T.List[T.Union[str, IdNode, IndexNode]]
+            command: T.List[T.Union[str, IdNode, IndexNode]] = []
             command += mesonlib.get_meson_command()
             command += ['--internal', 'cmake_run_ctgt']
             command += ['-o', '@OUTPUT@']
@@ -1226,12 +1226,12 @@ class CMakeInterpreter:
             for cmd in tgt.command:
                 command += [resolve_source(x) for x in cmd] + [';;;']
 
-            tgt_kwargs = {
+            tgt_kwargs: TYPE_mixed_kwargs = {
                 'input': [resolve_source(x) for x in tgt.inputs],
                 'output': tgt.outputs,
                 'command': command,
                 'depends': [resolve_source(x) for x in tgt.depends],
-            }  # type: TYPE_mixed_kwargs
+            }
 
             root_cb.lines += [assign(tgt_var, function('custom_target', [tgt.name], tgt_kwargs))]
             processed[tgt.name] = {'inc': None, 'src': None, 'dep': None, 'tgt': tgt_var, 'func': 'custom_target'}