From a07871b9cd1b5a1469271be6aaac5766f5a0e0fc Mon Sep 17 00:00:00 2001
From: Jelle Zijlstra <jelle.zijlstra@gmail.com>
Date: Wed, 3 May 2023 08:43:20 -0700
Subject: [PATCH] Fix new mypy error in blib2to3 (#3674)

See python/mypy#15174
---
 src/blib2to3/pgen2/tokenize.py     | 11 ++++++-----
 tests/data/simple_cases/fstring.py |  4 ++++
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/src/blib2to3/pgen2/tokenize.py b/src/blib2to3/pgen2/tokenize.py
index a6353d1..82ac513 100644
--- a/src/blib2to3/pgen2/tokenize.py
+++ b/src/blib2to3/pgen2/tokenize.py
@@ -163,7 +163,6 @@ endprogs: Final = {
     '"""': double3prog,
     **{f"{prefix}'''": single3prog for prefix in _strprefixes},
     **{f'{prefix}"""': double3prog for prefix in _strprefixes},
-    **{prefix: None for prefix in _strprefixes},
 }
 
 triple_quoted: Final = (
@@ -599,11 +598,13 @@ def generate_tokens(
                 ):
                     if token[-1] == "\n":  # continued string
                         strstart = (lnum, start)
-                        endprog = (
-                            endprogs[initial]
-                            or endprogs[token[1]]
-                            or endprogs[token[2]]
+                        maybe_endprog = (
+                            endprogs.get(initial)
+                            or endprogs.get(token[1])
+                            or endprogs.get(token[2])
                         )
+                        assert maybe_endprog is not None, f"endprog not found for {token}"
+                        endprog = maybe_endprog
                         contstr, needcont = line[start:], 1
                         contline = line
                         break
diff --git a/tests/data/simple_cases/fstring.py b/tests/data/simple_cases/fstring.py
index 4b33231..6056030 100644
--- a/tests/data/simple_cases/fstring.py
+++ b/tests/data/simple_cases/fstring.py
@@ -7,6 +7,8 @@ f"{f'''{'nested'} inner'''} outer"
 f"\"{f'{nested} inner'}\" outer"
 f"space between opening braces: { {a for a in (1, 2, 3)}}"
 f'Hello \'{tricky + "example"}\''
+f"Tried directories {str(rootdirs)} \
+but none started with prefix {parentdir_prefix}"
 
 # output
 
@@ -19,3 +21,5 @@ f"{f'''{'nested'} inner'''} outer"
 f"\"{f'{nested} inner'}\" outer"
 f"space between opening braces: { {a for a in (1, 2, 3)}}"
 f'Hello \'{tricky + "example"}\''
+f"Tried directories {str(rootdirs)} \
+but none started with prefix {parentdir_prefix}"
-- 
2.39.2