Split `write_temporary_file() from save_traceback()`

sphinx/_cli/util/errors.py

@@ -113,10 +113,16 @@ def format_traceback(app: Sphinx | None, exc: BaseException) -> str:
 def save_traceback(app: Sphinx | None, exc: BaseException) -> str:
     """Save the given exception's traceback in a temporary file."""
     output = format_traceback(app=app, exc=exc)
+    filename = write_temporary_file(output)
+    return filename
+
+
+def write_temporary_file(content: str) -> str:
+    """Write content to a temporary file and return the filename."""
     with tempfile.NamedTemporaryFile(
-        suffix='.log', prefix='sphinx-err-', delete=False
+        'w', encoding='utf-8', suffix='.log', prefix='sphinx-err-', delete=False
     ) as f:
-        f.write(error_info(last_msgs, exts_list, exc_format).encode('utf-8'))
+        f.write(content)
 
     return f.name
 

sphinx/util/exceptions.py

@@ -2,22 +2,10 @@ from __future__ import annotations
 
 import sys
 import traceback
-from tempfile import NamedTemporaryFile
-from typing import TYPE_CHECKING
 
-from sphinx._cli.util.errors import format_traceback
+from sphinx._cli.util.errors import save_traceback
 
-if TYPE_CHECKING:
-    from sphinx.application import Sphinx
-
-
-def save_traceback(app: Sphinx | None, exc: BaseException) -> str:
-    """Save the given exception's traceback in a temporary file."""
-    with NamedTemporaryFile(
-        'w', encoding='utf-8', suffix='.log', prefix='sphinx-err-', delete=False
-    ) as f:
-        f.write(format_traceback(app, exc))
-    return f.name
+__all__ = 'save_traceback', 'format_exception_cut_frames'
 
 
 def format_exception_cut_frames(x: int = 1) -> str: