2to3 import fixer writes dotted_as_names into import_as_names

[simonmweber]

BPO	22425
Nosy	@benjaminp
Superseder	bpo-45544: Close 2to3 issues and list them here

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2021-10-20.22:45:13.073>
created_at = <Date 2014-09-16.21:00:27.078>
labels = ['type-bug', 'expert-2to3']
title = '2to3 import fixer writes dotted_as_names into import_as_names'
updated_at = <Date 2021-10-20.22:45:13.072>
user = 'https://bugs.python.org/simonmweber'

bugs.python.org fields:

activity = <Date 2021-10-20.22:45:13.072>
actor = 'iritkatriel'
assignee = 'none'
closed = True
closed_date = <Date 2021-10-20.22:45:13.073>
closer = 'iritkatriel'
components = ['2to3 (2.x to 3.x conversion tool)']
creation = <Date 2014-09-16.21:00:27.078>
creator = 'simonmweber'
dependencies = []
files = []
hgrepos = []
issue_num = 22425
keywords = []
message_count = 1.0
messages = ['226965']
nosy_count = 3.0
nosy_names = ['benjamin.peterson', 'Arfrever', 'simonmweber']
pr_nums = []
priority = 'normal'
resolution = 'wont fix'
stage = 'resolved'
status = 'closed'
superseder = '45544'
type = 'behavior'
url = 'https://bugs.python.org/issue22425'
versions = ['Python 2.7', 'Python 3.4']

[simonmweber]

When dealing with implicit relative imports of the form "import <dotted_as_names> as...", the 2to3 import fixer will rewrite them as "from . import <dotted_as_names> as...".

This is invalid syntax. Here's an example:

$ tree package/
package/
├── __init__.py
├── rootmod.py
└── subpackage
    ├── __init__.py
    └── mod.py

1 directory, 4 files

$ cat package/rootmod.py  # this is the only nonempty file
import subpackage.mod as my_name

$ python package/rootmod.py

$ 2to3 -w -f import package/
RefactoringTool: Refactored package/rootmod.py
--- package/rootmod.py	(original)
+++ package/rootmod.py	(refactored)
@@ -1 +1 @@
-import subpackage.mod as my_name
+from . import subpackage.mod as my_name
RefactoringTool: Files that were modified:
RefactoringTool: package/rootmod.py

$ python package/rootmod.py
  File "package/rootmod.py", line 1
    from . import subpackage.mod as my_name
                            ^
SyntaxError: invalid syntax

Probably the easiest way to rewrite this is "from .subpackage import mod as my_name".