New submission from Emanuel Barry <>:

This is a follow-up to Issue27364.

Back in Python 3.6, a silent warning was added for all invalid escape sequences 
in str and bytes. It was suggested that it would remain a silent warning (which 
still impacts tests, while not visually annoying the average user) for two 
releases (3.6 and 3.7), then would be upgraded to a non-silent warning for two 
subsequent releases (3.8 and 3.9) before becoming a full-on syntax error. With 
the 3.7 feature freeze on and going, I think it's time to evaluate the approach 
we take for 3.8 :)

I suggest upgrading the DeprecationWarning to a SyntaxWarning, which is visible 
by default, for 3.8 and 3.9. I have cross-linked #27364 to this issue as well.


components: Interpreter Core
messages: 312575
nosy: ebarry
priority: normal
severity: normal
stage: needs patch
status: open
title: Raise non-silent warning for invalid escape sequences
type: behavior
versions: Python 3.8

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