[docs] Include a real listing of the flags strict enables in the online documentation

docs/source/command_line.rst

@@ -764,7 +764,10 @@ of the above sections.
     :option:`mypy --help` output.
 
     Note: the exact list of flags enabled by running :option:`--strict` may change
-    over time.
+    over time. For this version of mypy, the list is:
+
+    .. include:: strict_list.rst
+
 
 .. option:: --disable-error-code
 

docs/source/html_builder.py

@@ -11,16 +11,35 @@
 from sphinx.builders.html import StandaloneHTMLBuilder
 from sphinx.environment import BuildEnvironment
 
+from mypy.main import process_options
+
 
 class MypyHTMLBuilder(StandaloneHTMLBuilder):
+    strict_file: Path
+
     def __init__(self, app: Sphinx, env: BuildEnvironment) -> None:
         super().__init__(app, env)
         self._ref_to_doc = {}
+        self.strict_file = Path(self.srcdir) / "strict_list.rst"
+        self._add_strict_list()
 
     def write_doc(self, docname: str, doctree: document) -> None:
         super().write_doc(docname, doctree)
         self._ref_to_doc.update({_id: docname for _id in doctree.ids})
 
+    def _add_strict_list(self) -> None:
+        strict_flags: list[str] = []
+        process_options(["-c", "pass"], list_to_fill_with_strict_flags=strict_flags)
+        strict_part = ", ".join(f":option:`{s} <mypy {s}>`" for s in strict_flags)
+        if (
+            not strict_part
+            or strict_part.isspace()
+            or len(strict_part) < 20
+            or len(strict_part) > 2000
+        ):
+            raise ValueError(f"{strict_part=}, which doesn't look right (by a simple heuristic).")
+        self.strict_file.write_text(strict_part)
+
     def _verify_error_codes(self) -> None:
         from mypy.errorcodes import error_codes
 
@@ -55,6 +74,7 @@ def _write_ref_redirector(self) -> None:
     def finish(self) -> None:
         super().finish()
         self._write_ref_redirector()
+        self.strict_file.unlink()
 
 
 def setup(app: Sphinx) -> dict[str, Any]:

mypy/main.py

@@ -471,11 +471,18 @@ def process_options(
     fscache: FileSystemCache | None = None,
     program: str = "mypy",
     header: str = HEADER,
+    list_to_fill_with_strict_flags: list[str] | None = None,
 ) -> tuple[list[BuildSource], Options]:
     """Parse command line arguments.
 
     If a FileSystemCache is passed in, and package_root options are given,
     call fscache.set_package_root() to set the cache's package root.
+
+    Returns a tuple of: a list of source files, an Options collected from flags.
+
+    If list_to_fill_with_strict_flags is provided and not none,
+      then that list will be extended with the computed list of flags that --strict enables
+      (as a sort of secret return option).
     """
     stdout = stdout or sys.stdout
     stderr = stderr or sys.stderr
@@ -1502,11 +1509,9 @@ def set_strict_flags() -> None:
             targets.extend(p_targets)
         for m in special_opts.modules:
             targets.append(BuildSource(None, m, None))
-        return targets, options
     elif special_opts.command:
         options.build_type = BuildType.PROGRAM_TEXT
         targets = [BuildSource(None, None, "\n".join(special_opts.command))]
-        return targets, options
     else:
         try:
             targets = create_source_list(special_opts.files, options, fscache)
@@ -1515,7 +1520,9 @@ def set_strict_flags() -> None:
         # exceptions of different types.
         except InvalidSourceList as e2:
             fail(str(e2), stderr, options)
-        return targets, options
+    if list_to_fill_with_strict_flags is not None:
+        list_to_fill_with_strict_flags.extend(strict_flag_names)
+    return targets, options
 
 
 def process_package_roots(