Crash when docstring is reindented and a line ends in a backslash

[JelleZijlstra]

This is another one from #1053

$ cat backslashdoc.py 
def xxx_xxxxxx_xxxxx_xx_xxxx():
    """xxxxxx x xxxx xx xx xxxxxxxx xxx xxxxx xx xxx xxxxxxx xxxxxx.

    xxxx_xx       = xx - (1 + xxxxxxxx_xxxx)
    xxxx_xx_xxxxx = xx - (1 + xxxxxxxx_xxxx) - (xxxxxx - 1) \
                  = xx - (xxxxxxxx_xxxx + xxxxxx)

   xxx xxxxx xxxxx xxxxxxxxxxxx xxxx xxx xxxxxxx xxxx xxxx xxxxxxx xx

    """
$ black backslashdoc.py 
error: cannot format backslashdoc.py: INTERNAL ERROR: Black produced code that is not equivalent to the source.  Please report a bug on https://github.com/psf/black/issues.  This diff might be helpful: /var/folders/wx/zkst6jdx1zg_s32d23gz4_0r0000gn/T/blk_hx7_mm1z.log
Oh no! 💥 💔 💥
1 file failed to reformat.
$ cat  /var/folders/wx/zkst6jdx1zg_s32d23gz4_0r0000gn/T/blk_hx7_mm1z.log
--- src
+++ dst
@@ -16,11 +16,11 @@
       body=
         Expr(
           value=
             Constant(
               value=
-                'xxxxxx x xxxx xx xx xxxxxxxx xxx xxxxx xx xxx xxxxxxx xxxxxx.\n\nxxxx_xx       = xx - (1 + xxxxxxxx_xxxx)\nxxxx_xx_xxxxx = xx - (1 + xxxxxxxx_xxxx) - (xxxxxx - 1)                   = xx - (xxxxxxxx_xxxx + xxxxxx)\n\nxxx xxxxx xxxxx xxxxxxxxxxxx xxxx xxx xxxxxxx xxxx xxxx xxxxxxx xx',  # str
+                'xxxxxx x xxxx xx xx xxxxxxxx xxx xxxxx xx xxx xxxxxxx xxxxxx.\n\nxxxx_xx       = xx - (1 + xxxxxxxx_xxxx)\nxxxx_xx_xxxxx = xx - (1 + xxxxxxxx_xxxx) - (xxxxxx - 1)                    = xx - (xxxxxxxx_xxxx + xxxxxx)\n\nxxx xxxxx xxxxx xxxxxxxxxxxx xxxx xxx xxxxxxx xxxx xxxx xxxxxxx xx',  # str
             )  # /Constant
         )  # /Expr
       decorator_list=
       name=
         'xxx_xxxxxx_xxxxx_xx_xxxx',  # str

[ichard26]

Fixed by #1623 as now Black ignores docstrings with backslash newline escapes.

black/src/black/__init__.py

Lines 2040 to 2042 in 9270a10

	if is_docstring(leaf) and "\\\n" not in leaf.value:
	# We're ignoring docstrings with backslash newline escapes because changing
	# indentation of those changes the AST representation of the code.

(black-rHKUX7ap) R:\Programming\black>git fetch upstream
[snip]
(black-rHKUX7ap) R:\Programming\black>git merge upstream/master
[snip]
(black-rHKUX7ap) R:\Programming\black>cat temp.py
'cat' is not recognized as an internal or external command,
operable program or batch file.

(black-rHKUX7ap) R:\Programming\black>type temp.py
def xxx_xxxxxx_xxxxx_xx_xxxx():
    """xxxxxx x xxxx xx xx xxxxxxxx xxx xxxxx xx xxx xxxxxxx xxxxxx.

    xxxx_xx       = xx - (1 + xxxxxxxx_xxxx)
    xxxx_xx_xxxxx = xx - (1 + xxxxxxxx_xxxx) - (xxxxxx - 1) \
                  = xx - (xxxxxxxx_xxxx + xxxxxx)

   xxx xxxxx xxxxx xxxxxxxxxxxx xxxx xxx xxxxxxx xxxx xxxx xxxxxxx xx

    """
(black-rHKUX7ap) R:\Programming\black>black temp.py --check
would reformat temp.py
Oh no! 💥 💔 💥
1 file would be reformatted.