[3.6] bpo-30682: Removed a too-strict assertion that failed for certain f-strings. (GH-2232) (#2242)
This caused a segfault on eval("f'\\\n'") and eval("f'\\\r'") in debug build..
(cherry picked from commit 11e97f2f80bf65cc828c127eafc95229df35d403)diff --git a/Lib/test/test_fstring.py b/Lib/test/test_fstring.py
index b398704..3d762b5 100644
--- a/Lib/test/test_fstring.py
+++ b/Lib/test/test_fstring.py
@@ -780,5 +780,11 @@
self.assertEqual(f'{d["foo"]}', 'bar')
self.assertEqual(f"{d['foo']}", 'bar')
+ def test_backslash_char(self):
+ # Check eval of a backslash followed by a control char.
+ # See bpo-30682: this used to raise an assert in pydebug mode.
+ self.assertEqual(eval('f"\\\n"'), '')
+ self.assertEqual(eval('f"\\\r"'), '')
+
if __name__ == '__main__':
unittest.main()
diff --git a/Misc/NEWS b/Misc/NEWS
index 1c6eb72..fd7ebf9 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -10,6 +10,9 @@
Core and Builtins
-----------------
+- bpo-30682: Removed a too-strict assertion that failed for certain f-strings,
+ such as eval("f'\\\n'") and eval("f'\\\r'").
+
- bpo-30604: Move co_extra_freefuncs to not be per-thread to avoid crashes
- bpo-29104: Fixed parsing backslashes in f-strings.
diff --git a/Python/ast.c b/Python/ast.c
index c61ca4b..8d53736 100644
--- a/Python/ast.c
+++ b/Python/ast.c
@@ -4887,6 +4887,8 @@
/* Do nothing. Just leave last_str alone (and possibly
NULL). */
} else if (!state->last_str) {
+ /* Note that the literal can be zero length, if the
+ input string is "\\\n" or "\\\r", among others. */
state->last_str = literal;
literal = NULL;
} else {
@@ -4896,8 +4898,6 @@
return -1;
literal = NULL;
}
- assert(!state->last_str ||
- PyUnicode_GET_LENGTH(state->last_str) != 0);
/* We've dealt with the literal now. It can't be leaked on further
errors. */