Update open process types (#3076)

newsfragments/3076.bugfix.rst

@@ -0,0 +1 @@
+Update ``trio.lowlevel.open_process``'s documentation to allow bytes.

src/trio/_subprocess.py

@@ -304,7 +304,7 @@ def kill(self) -> None:
 
 
 async def _open_process(
-    command: list[str] | str,
+    command: StrOrBytesPath | Sequence[StrOrBytesPath],
     *,
     stdin: int | HasFileno | None = None,
     stdout: int | HasFileno | None = None,
@@ -329,13 +329,14 @@ async def _open_process(
     want.
 
     Args:
-      command (list or str): The command to run. Typically this is a
-          sequence of strings such as ``['ls', '-l', 'directory with spaces']``,
-          where the first element names the executable to invoke and the other
-          elements specify its arguments. With ``shell=True`` in the
-          ``**options``, or on Windows, ``command`` may alternatively
-          be a string, which will be parsed following platform-dependent
-          :ref:`quoting rules <subprocess-quoting>`.
+      command: The command to run. Typically this is a sequence of strings or
+          bytes such as ``['ls', '-l', 'directory with spaces']``, where the
+          first element names the executable to invoke and the other elements
+          specify its arguments. With ``shell=True`` in the ``**options``, or on
+          Windows, ``command`` can be a string or bytes, which will be parsed
+          following platform-dependent :ref:`quoting rules
+          <subprocess-quoting>`. In all cases ``command`` can be a path or a
+          sequence of paths.
       stdin: Specifies what the child process's standard input
           stream should connect to: output written by the parent
           (``subprocess.PIPE``), nothing (``subprocess.DEVNULL``),
@@ -369,15 +370,16 @@ async def _open_process(
             )
 
     if os.name == "posix":
-        if isinstance(command, str) and not options.get("shell"):
+        # TODO: how do paths and sequences thereof play with `shell=True`?
+        if isinstance(command, (str, bytes)) and not options.get("shell"):
             raise TypeError(
-                "command must be a sequence (not a string) if shell=False "
-                "on UNIX systems",
+                "command must be a sequence (not a string or bytes) if "
+                "shell=False on UNIX systems",
             )
-        if not isinstance(command, str) and options.get("shell"):
+        if not isinstance(command, (str, bytes)) and options.get("shell"):
             raise TypeError(
-                "command must be a string (not a sequence) if shell=True "
-                "on UNIX systems",
+                "command must be a string or bytes (not a sequence) if "
+                "shell=True on UNIX systems",
             )
 
     trio_stdin: ClosableSendStream | None = None

src/trio/_tools/gen_exports.py

@@ -303,7 +303,7 @@ def process(files: Iterable[File], *, do_test: bool) -> None:
             print("Generated sources are up to date.")
     else:
         for new_path, new_source in new_files.items():
-            with open(new_path, "w", encoding="utf-8") as f:
+            with open(new_path, "w", encoding="utf-8", newline="\n") as f:
                 f.write(new_source)
         print("Regenerated sources successfully.")
         if not matches_disk: