bpo-39545: Document changes in the support of await in f-strings. (GH-18456)
https://bugs.python.org/issue39545
diff --git a/Doc/reference/lexical_analysis.rst b/Doc/reference/lexical_analysis.rst
index c0e13b5..3d4b03e 100644
--- a/Doc/reference/lexical_analysis.rst
+++ b/Doc/reference/lexical_analysis.rst
@@ -685,6 +685,11 @@
in the context where the formatted string literal appears, in order from
left to right.
+.. versionchanged:: 3.7
+ Prior to Python 3.7, an :keyword:`await` expression and comprehensions
+ containing an :keyword:`async for` clause were illegal in the expressions
+ in formatted string literals due to a problem with the implementation.
+
If a conversion is specified, the result of evaluating the expression
is converted before formatting. Conversion ``'!s'`` calls :func:`str` on
the result, ``'!r'`` calls :func:`repr`, and ``'!a'`` calls :func:`ascii`.