bpo-38871: Fix lib2to3 for filter-based statements that contain lambda (GH-17780)
Correctly parenthesize filter-based statements that contain lambda
expressions in lib2to3.
diff --git a/Lib/lib2to3/fixes/fix_filter.py b/Lib/lib2to3/fixes/fix_filter.py
index a7a5a15..38e9078 100644
--- a/Lib/lib2to3/fixes/fix_filter.py
+++ b/Lib/lib2to3/fixes/fix_filter.py
@@ -17,7 +17,7 @@
from .. import fixer_base
from ..pytree import Node
from ..pygram import python_symbols as syms
-from ..fixer_util import Name, ArgList, ListComp, in_special_context
+from ..fixer_util import Name, ArgList, ListComp, in_special_context, parenthesize
class FixFilter(fixer_base.ConditionalFix):
@@ -65,10 +65,14 @@
trailers.append(t.clone())
if "filter_lambda" in results:
+ xp = results.get("xp").clone()
+ if xp.type == syms.test:
+ xp.prefix = ""
+ xp = parenthesize(xp)
+
new = ListComp(results.get("fp").clone(),
results.get("fp").clone(),
- results.get("it").clone(),
- results.get("xp").clone())
+ results.get("it").clone(), xp)
new = Node(syms.power, [new] + trailers, prefix="")
elif "none" in results:
diff --git a/Lib/lib2to3/tests/test_fixers.py b/Lib/lib2to3/tests/test_fixers.py
index 3da5dd8..a285241 100644
--- a/Lib/lib2to3/tests/test_fixers.py
+++ b/Lib/lib2to3/tests/test_fixers.py
@@ -2954,6 +2954,11 @@
a = """x = [x for x in range(10) if x%2 == 0]"""
self.check(b, a)
+ # bpo-38871
+ b = """filter(lambda x: True if x > 2 else False, [1, 2, 3])"""
+ a = """[x for x in [1, 2, 3] if (True if x > 2 else False)]"""
+ self.check(b, a)
+
def test_filter_trailers(self):
b = """x = filter(None, 'abc')[0]"""
a = """x = [_f for _f in 'abc' if _f][0]"""
diff --git a/Misc/NEWS.d/next/Library/2020-01-01-18-44-52.bpo-38871.3EEOLg.rst b/Misc/NEWS.d/next/Library/2020-01-01-18-44-52.bpo-38871.3EEOLg.rst
new file mode 100644
index 0000000..fe970fd
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2020-01-01-18-44-52.bpo-38871.3EEOLg.rst
@@ -0,0 +1,2 @@
+Correctly parenthesize filter-based statements that contain lambda
+expressions in mod:`lib2to3`. Patch by Dong-hee Na.