bpo-28739: Document that f-strings cannot be used as docstring (GH-592)
diff --git a/Doc/reference/lexical_analysis.rst b/Doc/reference/lexical_analysis.rst
index da7017a..7f9c664 100644
--- a/Doc/reference/lexical_analysis.rst
+++ b/Doc/reference/lexical_analysis.rst
@@ -696,6 +696,17 @@
>>> f"newline: {newline}"
'newline: 10'
+Formatted string literals cannot be used as docstrings, even if they do not
+include expressions.
+
+::
+
+ >>> def foo():
+ ... f"Not a docstring"
+ ...
+ >>> foo.__doc__ is None
+ True
+
See also :pep:`498` for the proposal that added formatted string literals,
and :meth:`str.format`, which uses a related format string mechanism.