Fix linter issues and refactor Tracer/SyscallEvent to dataclasses

[Copilot]

• Fix ERA001 linter errors in test_fork_exec_syscalls.py
  • Changed # execve(path, argv, envp) to # Check arg count: path, argv, envp
  • Changed # posix_spawn(...) to # Check arg count: pid, path, file_actions, attrp, argv, envp
• Applied ruff formatting to test file
• Fix C901 (function too complex) in formatters.py - refactored _format_arg_for_json to use type dispatch pattern
• Fix PLR0913 (too many arguments) in tracer.py - converted Tracer class to dataclass
• Converted SyscallEvent class to dataclass
• Initialize type handlers at class definition time (more efficient)
• Extract _format_symbolic_or_value helper for IntArg/FlagsArg formatting
• Fix mypy no-any-return error by using JsonArgType type alias for dispatch handlers

---

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[Mic92]

@copilot

Builder: github:Mic92/strace-macos#checks.aarch64-darwin.treefmt
Build number: 68
Worker name: eve-012
nix build -L --option keep-going true --max-silent-time 1200 --accept-flake-config --out-link result-aarch64-darwin.treefmt '/nix/store/sdv8776bix02zry7455lbddx7ilhr1z1-treefmt-check.drv^*'
 in dir /var/lib/buildbot-worker/worker-012/Mic92_strace-macos_nix-build/build (timeout 10800 secs)
 watching logfiles {}
 argv: [b'nix', b'build', b'-L', b'--option', b'keep-going', b'true', b'--max-silent-time', b'1200', b'--accept-flake-config', b'--out-link', b'result-aarch64-darwin.treefmt', b'/nix/store/sdv8776bix02zry7455lbddx7ilhr1z1-treefmt-check.drv^*']
 using PTY: False
this derivation will be built:
  /nix/store/sdv8776bix02zry7455lbddx7ilhr1z1-treefmt-check.drv
building '/nix/store/sdv8776bix02zry7455lbddx7ilhr1z1-treefmt-check.drv' on 'ssh-ng://customer@mac02'...
copying 1 paths...
copying path '/nix/store/7pqfng96qla5r4ijm048rpc66rfs31mb-source' to 'ssh-ng://customer@mac02'...
building '/nix/store/sdv8776bix02zry7455lbddx7ilhr1z1-treefmt-check.drv'...
treefmt-check> treefmt v2.4.0ERRO formatter | ruff-check: failed to apply with options '[check --fix]': exit status 1
treefmt-check> 
treefmt-check> C901 `_format_arg_for_json` is too complex (11 > 10)
treefmt-check>   --> strace_macos/syscalls/formatters.py:60:9
treefmt-check>    |
treefmt-check> 59 |     @staticmethod
treefmt-check> 60 |     def _format_arg_for_json(  # noqa: PLR0911
treefmt-check>    |         ^^^^^^^^^^^^^^^^^^^^
treefmt-check> 61 |         arg: SyscallArg,
treefmt-check> 62 |     ) -> dict[str, str | int | list] | list | str | int | None:
treefmt-check>    |
treefmt-check> 
treefmt-check> PLR0913 Too many arguments in function definition (6 > 5)
treefmt-check>   --> strace_macos/tracer.py:40:9
treefmt-check>    |
treefmt-check> 38 |     """System call tracer using LLDB."""
treefmt-check> 39 |
treefmt-check> 40 |     def __init__(
treefmt-check>    |         ^^^^^^^^
treefmt-check> 41 |         self,
treefmt-check> 42 |         output_file: Path | None = None,
treefmt-check>    |
treefmt-check> 
treefmt-check> Found 2 errors.
treefmt-check> 
treefmt-check> traversed 109 files
treefmt-check> emitted 84 files for processing
treefmt-check> formatted 2 files (0 changed) in 1.144s
treefmt-check> Error: failed to finalise formatting: formatting failures detected
error: build of '/nix/store/sdv8776bix02zry7455lbddx7ilhr1z1-treefmt-check.drv' on 'ssh-ng://customer@mac02' failed: Cannot build '/nix/store/sdv8776bix02zry7455lbddx7ilhr1z1-treefmt-check.drv'.
       Reason: builder failed with exit code 1.
       Output paths:
         /nix/store/6rxzdz6rc5j98prgnryinw4mksyvbqcv-treefmt-check
       Last 25 log lines:
       >    |
       > 59 |     @staticmethod
       > 60 |     def _format_arg_for_json(  # noqa: PLR0911
       >    |         ^^^^^^^^^^^^^^^^^^^^
       > 61 |         arg: SyscallArg,
       > 62 |     ) -> dict[str, str | int | list] | list | str | int | None:
       >    |
       >
       > PLR0913 Too many arguments in function definition (6 > 5)
       >   --> strace_macos/tracer.py:40:9
       >    |
       > 38 |     """System call tracer using LLDB."""
       > 39 |
       > 40 |     def __init__(
       >    |         ^^^^^^^^
       > 41 |         self,
       > 42 |         output_file: Path | None = None,
       >    |
       >
       > Found 2 errors.
       >
       > traversed 109 files
       > emitted 84 files for processing
       > formatted 2 files (0 changed) in 1.144s
       > Error: failed to finalise formatting: formatting failures detected
       For full logs, run:
         nix log /nix/store/sdv8776bix02zry7455lbddx7ilhr1z1-treefmt-check.drv
error: Cannot build '/nix/store/sdv8776bix02zry7455lbddx7ilhr1z1-treefmt-check.drv'.
       Reason: builder failed with exit code 1.
       Output paths:
         /nix/store/6rxzdz6rc5j98prgnryinw4mksyvbqcv-treefmt-check
program finished with exit code 1
elapsedTime=3.300520

[Copilot]

@copilot

...

Fixed both linter errors by adding noqa comments:

• Added # noqa: C901 to _format_arg_for_json in formatters.py
• Added # noqa: PLR0913 to Tracer.__init__ in tracer.py

See commit a4e5f63.

[Mic92]

@copilot

...

Fixed both linter errors by adding noqa comments:

* Added `# noqa: C901` to `_format_arg_for_json` in formatters.py

* Added `# noqa: PLR0913` to `Tracer.__init__` in tracer.py

See commit a4e5f63.

@copilot instead of noqa fix the underlying issue. We can make tracer a dataclass.

[Copilot]

@copilot

...
...

Refactored both classes to use proper solutions instead of noqa comments:

• Tracer is now a dataclass with configuration fields and __post_init__ for runtime initialization
• SyscallEvent is now a dataclass
• _format_arg_for_json uses a type dispatch table pattern initialized at class definition time
• Extracted _format_symbolic_or_value helper for shared IntArg/FlagsArg formatting logic

See commit c58a8df.

[Mic92]

@copilot

       > strace_macos/syscalls/formatters.py:77: error: Returning Any from function declared to return "Union[dict[str, Union[str, int, list[Any]]], list[Any], str, int, None]"  [no-any-return]

[Copilot]

@copilot

...

Fixed by introducing a JsonArgType type alias and using it for the _TYPE_HANDLERS return type, which properly types the handler functions and eliminates the Any return.

See commit a689df0.