fixhunt

ruff RUF047

labelled unknown
Runs / 2026-10-17T21-46-01-959Z-m6i5-ruff-RUF047ruff 0.17.12026-10-17 21:46 UTC8 programs × 2 round(s)16 programs, 7 fired, 7 fixed, 0 findings, 3 rejectedmodel cost $0.0052

Analysis Nemotron 3 Super

Flags unnecessary else blocks containing only pass or ellipsis statements.

Fix: Removes the else block entirely, dedenting any following code to the same level as the if/while/for/try statement.

12 hazards
  • The else block may contain a docstring or comment that provides important context or API documentation, which would be lost upon removal.
  • If the else block is part of a try-except-else-finally construct, removing it could alter control flow when no exception occurs, potentially skipping cleanup or logging intended for the success path.
  • In nested conditional structures, removing an else block could change the indentation of subsequent code, causing it to be incorrectly associated with an outer block.
  • The pass or ellipsis statement might be intentionally used as a placeholder for future implementation; removing it could obscure developer intent or break code generation tools that rely on its presence.
  • If the else block is followed by a comment on the same line or inline, that comment may be incorrectly attached to the preceding block or lost during rewriting.
  • In code that relies on the else block for structural symmetry (e.g., code generation or templating), its removal could break expected patterns or formatting rules.
  • The rewrite assumes the else block is syntactically isolated; however, if it contains only a trailing comment after pass/..., the comment's association may be misinterpreted during parsing.
  • In interactive or debugging contexts, the else block might host a breakpoint via pass; removing it could eliminate a deliberate stop point for debugging.
  • If the else block is part of a one-line compound statement (e.g., 'if x: y()\nelse: pass'), the fix may not apply due to formatting constraints, but if forced, could disrupt line-based tooling like coverage or blame.
  • The removal could affect tools that track cyclomatic complexity or code coverage metrics, as the else branch—even if empty—may be counted as a testable path.
  • In rare cases, the else block might be present to satisfy a syntactic requirement in a macro-generated or metaprogrammed context where empty branches are significant.
  • If the else block is immediately followed by a decorator or class/function definition at the same indentation level, removing it could cause misalignment in the AST, leading to incorrect binding of subsequent definitions.

Programs

idresulttitlehazard
r1-p001fix okType annotation evaluation triggers unwanted removaltype annotations evaluated at runtime, typing-only imports
r1-p002silent prediction offElse block used as syntactic placeholder in metaprogrammingIn rare cases, the else block might be present to satisfy a syntactic requirement in a macro-generated or metaprogrammed context where empty branches are significant.
r1-p003silent prediction offComment on else block lost after fixcomments and docstrings attached to the removed or moved code
r1-p004silent prediction offDebugging breakpoint via pass eliminatedIn interactive or debugging contexts, the else block might host a breakpoint via pass; removing it could eliminate a deliberate stop point for debugging.
r1-p005invalidOne-line compound statement disruptedIf the else block is part of a one-line compound statement (e.g., 'if x: y()\nelse: pass'), the fix may not apply due to formatting constraints, but if forced, could disrupt line-based tooling like co
r1-p006fix okAsync function with else pass interferes with awaitasync def/await ordering, async generators
r1-p007fix okElse removal causes misaligned function definitionIf the else block is immediately followed by a decorator or class/function definition at the same indentation level, removing it could cause misalignment in the AST, leading to incorrect binding of su
r1-p008fix okKeyword-only args with else pass in default evaluationkeyword-only, positional-only, *args/**kwargs forwarding, defaults evaluated once
r2-p001silent prediction offDocstring in else block lost after fixComment or docstring in else block providing API context is removed by fix
r2-p002fix okBinary mode file writing affected by else removalBytes vs str, encoding, newline handling in binary/text modes altered by dedentation after else removal
r2-p003fix okClass attribute descriptor side effect skippedClass attributes, descriptors, properties with side effects not triggered due to else removal changing execution path
r2-p004invalidOne-line compound statement else block formatting hazardElse block in one-line compound statement may not be fixed correctly, disrupting line-based tools
r2-p005silent prediction offMetaprogramming syntactic placeholder else blockElse block present to satisfy syntactic requirement in macro-generated code, removal breaks structure
r2-p006fix okKeyword-only argument default evaluation affectedKeyword-only args with else pass in default evaluation changed by control flow alteration
r2-p007silent prediction offInline comment after else block lost during fixComment on same line as else block incorrectly attached or lost during rewriting
r2-p008invalidGenerator consumption misaligned due to else removalGenerators vs lists, iterators consumed once, lazy evaluation broken by incorrect dedentation

Sources

r1-p001 · Type annotation evaluation triggers unwanted removal
1import typing
2T = typing.List[int]
3def f(x):
4 if isinstance(x, T):
5 return len(x)
6 else:
7 pass
8print(f([1, 2]))
9print(f("hi"))
--- orig.py	2026-10-17 17:46:22.503971022 -0400
+++ fixed.py	2026-10-17 17:46:22.895057924 -0400
@@ -3,7 +3,5 @@
 def f(x):
     if isinstance(x, T):
         return len(x)
-    else:
-        pass
 print(f([1, 2]))
 print(f("hi"))
r1-p002 · Else block used as syntactic placeholder in metaprogramming
1def make_condition(v):
2 return v > 0
3code_lines = [
4 'if make_condition(x):',
5 ' print("pos")',
6 'else:',
7 ' pass'
8]
9exec('\n'.join(code_lines))
10# After fix, the 'else:' line may be orphaned or cause IndentationError
r1-p003 · Comment on else block lost after fix
1def process(val):
2 if val:
3 return val * 2
4 else:
5 # TODO: handle zero case
6 pass
7print(process(5))
8print(process(0)) # Should print None, but comment loss may hint at refactoring risk
10
None
r1-p004 · Debugging breakpoint via pass eliminated
1def buggy(x):
2 if x > 10:
3 return x
4 else:
5 pass # breakpoint here
6result = buggy(5)
7print("Result:", result)
8# After fix, breakpoint is gone; no way to stop in else branch
Result: None
r1-p005 · One-line compound statement disrupted (generated program does not parse: Traceback (most recent call last):)
1if False: print("a"); else: pass
2print("executed")
3# This is a syntax error in Python; Ruff won't trigger on invalid syntax.
4# So we use a valid one-liner that Ruff may ignore due to formatting.
r1-p006 · Async function with else pass interferes with await
1async def async_fn():
2 await asyncio.sleep(0.01)
3 if True:
4 return 42
5 else:
6 pass
7import asyncio
8async def main():
9 result = await async_fn()
10 print("Result:", result)
11asyncio.run(main())
--- orig.py	2026-10-17 17:46:23.859271865 -0400
+++ fixed.py	2026-10-17 17:46:24.163339259 -0400
@@ -2,8 +2,6 @@
     await asyncio.sleep(0.01)
     if True:
         return 42
-    else:
-        pass
 import asyncio
 async def main():
     result = await async_fn()

Result: 42
r1-p007 · Else removal causes misaligned function definition
1def outer():
2 if False:
3 pass
4 else:
5 pass
6 def inner():
7 return 1
8 return inner()
9print(outer())
10# After fix, the dedented 'def inner' may be incorrectly associated or cause IndentationError
--- orig.py	2026-10-17 17:46:24.348380241 -0400
+++ fixed.py	2026-10-17 17:46:24.509415906 -0400
@@ -1,8 +1,6 @@
 def outer():
     if False:
         pass
-    else:
-        pass
     def inner():
         return 1
     return inner()

1
r1-p008 · Keyword-only args with else pass in default evaluation
1DEFAULT = []
2def func(a, *, b=DEFAULT):
3 if a is None:
4 b.append(1)
5 return b
6 else:
7 pass
8 return b
9print(func(None))
10print(func(None)) # Shows mutable default accumulation
11# If else removed, behavior unchanged, but rule still triggers
--- orig.py	2026-10-17 17:46:24.610438280 -0400
+++ fixed.py	2026-10-17 17:46:24.778475495 -0400
@@ -3,8 +3,6 @@
     if a is None:
         b.append(1)
         return b
-    else:
-        pass
     return b
 print(func(None))
 print(func(None))  # Shows mutable default accumulation

[1]
[1, 1]
r2-p001 · Docstring in else block lost after fix
1def f(x):
2 if x > 0:
3 return x * 2
4 else:
5 '''Handles non-positive inputs by returning zero.'''
6 pass
7print(f(5))
8print(f(-1))
10
None
r2-p002 · Binary mode file writing affected by else removal
1data = b'hello'
2if len(data) == 5:
3 with open('out.bin', 'wb') as f:
4 f.write(data)
5else:
6 pass
7with open('out.bin', 'rb') as f:
8 print(f.read())
9import os
10os.remove('out.bin')
--- orig.py	2026-10-17 17:46:30.392712545 -0400
+++ fixed.py	2026-10-17 17:46:30.554748076 -0400
@@ -2,8 +2,6 @@
 if len(data) == 5:
     with open('out.bin', 'wb') as f:
         f.write(data)
-else:
-    pass
 with open('out.bin', 'rb') as f:
     print(f.read())
 import os

b'hello'
r2-p003 · Class attribute descriptor side effect skipped
1class A:
2 x = 1
3 def __init__(self):
4 if hasattr(self, 'y'):
5 self.z = self.x
6 else:
7 pass
8 @property
9 def y(self):
10 return 99
11a = A()
12print(a.z)
--- orig.py	2026-10-17 17:46:30.648768693 -0400
+++ fixed.py	2026-10-17 17:46:30.819806198 -0400
@@ -3,8 +3,6 @@
     def __init__(self):
         if hasattr(self, 'y'):
             self.z = self.x
-        else:
-            pass
     @property
     def y(self):
         return 99

1
r2-p004 · One-line compound statement else block formatting hazard (generated program does not parse: Traceback (most recent call last):)
1if True: print('x'); else: pass
2print('done')
r2-p005 · Metaprogramming syntactic placeholder else block
1def make_func():
2 exec('''
3 def inner():
4 if 0:
5 pass
6 else:
7 pass # structural
8 ''')
9 return inner
10f = make_func()
11f()
12print('called')
r2-p006 · Keyword-only argument default evaluation affected
1def f(a, *, b=[]):
2 if False:
3 return
4 else:
5 pass
6 b.append(a)
7 return b
8print(f(1))
9print(f(2))
--- orig.py	2026-10-17 17:46:31.396932608 -0400
+++ fixed.py	2026-10-17 17:46:31.560968518 -0400
@@ -1,8 +1,6 @@
 def f(a, *, b=[]):
     if False:
         return
-    else:
-        pass
     b.append(a)
     return b
 print(f(1))

[1]
[1, 2]
r2-p007 · Inline comment after else block lost during fix
1if False:
2 x = 1
3else:
4 pass # important: fallback logic
5print(x if 'x' in locals() else 'undefined')
undefined
r2-p008 · Generator consumption misaligned due to else removal (generated program does not parse: Traceback (most recent call last):)
1def gen():
2 for i in range(3):
3 yield i
4g = gen()
5if True:
6 for x in g:
7 print(x, end='')
8else:
9 pass
10print('
11second:', list(gen()))