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`Style/RedundantParentheses` autocorrect introduces invalid syntax to expressions in conditional predicates · Issue #14557 · rubocop/rubocop · GitHub
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Style/RedundantParentheses autocorrect introduces invalid syntax to expressions in conditional predicates #14557

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#14558
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Style/RedundantParentheses autocorrect introduces invalid syntax to expressions in conditional predicates#14557
#14558
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bug
@patbl

Description

@patbl
patbl
opened on Sep 23, 2025

Expected behavior

Running rubocop --only Style/RedundantParentheses --autocorrect doesn't introduce invalid syntax into the following code:

unless (Integer("foo") rescue nil)
  puts '"foo" is not an Integer'
end

Actual behavior

Before:

$ cat parentheses.rb 
unless (Integer("foo") rescue nil)
  puts '"foo" is not an Integer'
end
$ ruby parentheses.rb 
"foo" is not an Integer
Running rubocop --only Style/RedundantParentheses --autocorrect removes the parentheses around Integer("foo") rescue nil, introducing invalid syntax. 
$ rubocop --only Style/RedundantParentheses --autocorrect --debug parentheses.rb 
For /Users/pat/Downloads/parentheses: Default configuration from /Users/pat/.local/share/mise/installs/ruby/3.4.1/lib/ruby/gems/3.4.0/gems/rubocop-1.80.2/config/default.yml
Use parallel by default.
The following cops were added to RuboCop, but are not configured. Please set Enabled to either `true` or `false` in your `.rubocop.yml` file.

Please also note that you can opt-in to new cops by default by adding this to your config:
  AllCops:
    NewCops: enable

Gemspec/AddRuntimeDependency: # new in 1.65
  Enabled: true
Gemspec/AttributeAssignment: # new in 1.77
  Enabled: true
Gemspec/DeprecatedAttributeAssignment: # new in 1.30
  Enabled: true
Gemspec/DevelopmentDependencies: # new in 1.44
  Enabled: true
Gemspec/RequireMFA: # new in 1.23
  Enabled: true
Layout/EmptyLinesAfterModuleInclusion: # new in 1.79
  Enabled: true
Layout/LineContinuationLeadingSpace: # new in 1.31
  Enabled: true
Layout/LineContinuationSpacing: # new in 1.31
  Enabled: true
Layout/LineEndStringConcatenationIndentation: # new in 1.18
  Enabled: true
Layout/SpaceBeforeBrackets: # new in 1.7
  Enabled: true
Lint/AmbiguousAssignment: # new in 1.7
  Enabled: true
Lint/AmbiguousOperatorPrecedence: # new in 1.21
  Enabled: true
Lint/AmbiguousRange: # new in 1.19
  Enabled: true
Lint/ArrayLiteralInRegexp: # new in 1.71
  Enabled: true
Lint/ConstantOverwrittenInRescue: # new in 1.31
  Enabled: true
Lint/ConstantReassignment: # new in 1.70
  Enabled: true
Lint/CopDirectiveSyntax: # new in 1.72
  Enabled: true
Lint/DeprecatedConstants: # new in 1.8
  Enabled: true
Lint/DuplicateBranch: # new in 1.3
  Enabled: true
Lint/DuplicateMagicComment: # new in 1.37
  Enabled: true
Lint/DuplicateMatchPattern: # new in 1.50
  Enabled: true
Lint/DuplicateRegexpCharacterClassElement: # new in 1.1
  Enabled: true
Lint/DuplicateSetElement: # new in 1.67
  Enabled: true
Lint/EmptyBlock: # new in 1.1
  Enabled: true
Lint/EmptyClass: # new in 1.3
  Enabled: true
Lint/EmptyInPattern: # new in 1.16
  Enabled: true
Lint/HashNewWithKeywordArgumentsAsDefault: # new in 1.69
  Enabled: true
Lint/IncompatibleIoSelectWithFiberScheduler: # new in 1.21
  Enabled: true
Lint/ItWithoutArgumentsInBlock: # new in 1.59
  Enabled: true
Lint/LambdaWithoutLiteralBlock: # new in 1.8
  Enabled: true
Lint/LiteralAssignmentInCondition: # new in 1.58
  Enabled: true
Lint/MixedCaseRange: # new in 1.53
  Enabled: true
Lint/NoReturnInBeginEndBlocks: # new in 1.2
  Enabled: true
Lint/NonAtomicFileOperation: # new in 1.31
  Enabled: true
Lint/NumberedParameterAssignment: # new in 1.9
  Enabled: true
Lint/NumericOperationWithConstantResult: # new in 1.69
  Enabled: true
Lint/OrAssignmentToConstant: # new in 1.9
  Enabled: true
Lint/RedundantDirGlobSort: # new in 1.8
  Enabled: true
Lint/RedundantRegexpQuantifiers: # new in 1.53
  Enabled: true
Lint/RedundantTypeConversion: # new in 1.72
  Enabled: true
Lint/RefinementImportMethods: # new in 1.27
  Enabled: true
Lint/RequireRangeParentheses: # new in 1.32
  Enabled: true
Lint/RequireRelativeSelfPath: # new in 1.22
  Enabled: true
Lint/SharedMutableDefault: # new in 1.70
  Enabled: true
Lint/SuppressedExceptionInNumberConversion: # new in 1.72
  Enabled: true
Lint/SymbolConversion: # new in 1.9
  Enabled: true
Lint/ToEnumArguments: # new in 1.1
  Enabled: true
Lint/TripleQuotes: # new in 1.9
  Enabled: true
Lint/UnescapedBracketInRegexp: # new in 1.68
  Enabled: true
Lint/UnexpectedBlockArity: # new in 1.5
  Enabled: true
Lint/UnmodifiedReduceAccumulator: # new in 1.1
  Enabled: true
Lint/UselessConstantScoping: # new in 1.72
  Enabled: true
Lint/UselessDefaultValueArgument: # new in 1.76
  Enabled: true
Lint/UselessDefined: # new in 1.69
  Enabled: true
Lint/UselessNumericOperation: # new in 1.66
  Enabled: true
Lint/UselessOr: # new in 1.76
  Enabled: true
Lint/UselessRescue: # new in 1.43
  Enabled: true
Lint/UselessRuby2Keywords: # new in 1.23
  Enabled: true
Metrics/CollectionLiteralLength: # new in 1.47
  Enabled: true
Naming/BlockForwarding: # new in 1.24
  Enabled: true
Naming/PredicateMethod: # new in 1.76
  Enabled: true
Security/CompoundHash: # new in 1.28
  Enabled: true
Security/IoMethods: # new in 1.22
  Enabled: true
Style/AmbiguousEndlessMethodDefinition: # new in 1.68
  Enabled: true
Style/ArgumentsForwarding: # new in 1.1
  Enabled: true
Style/ArrayIntersect: # new in 1.40
  Enabled: true
Style/BitwisePredicate: # new in 1.68
  Enabled: true
Style/CollectionCompact: # new in 1.2
  Enabled: true
Style/CollectionQuerying: # new in 1.77
  Enabled: true
Style/CombinableDefined: # new in 1.68
  Enabled: true
Style/ComparableBetween: # new in 1.74
  Enabled: true
Style/ComparableClamp: # new in 1.44
  Enabled: true
Style/ConcatArrayLiterals: # new in 1.41
  Enabled: true
Style/DataInheritance: # new in 1.49
  Enabled: true
Style/DigChain: # new in 1.69
  Enabled: true
Style/DirEmpty: # new in 1.48
  Enabled: true
Style/DocumentDynamicEvalDefinition: # new in 1.1
  Enabled: true
Style/EmptyHeredoc: # new in 1.32
  Enabled: true
Style/EmptyStringInsideInterpolation: # new in 1.76
  Enabled: true
Style/EndlessMethod: # new in 1.8
  Enabled: true
Style/EnvHome: # new in 1.29
  Enabled: true
Style/ExactRegexpMatch: # new in 1.51
  Enabled: true
Style/FetchEnvVar: # new in 1.28
  Enabled: true
Style/FileEmpty: # new in 1.48
  Enabled: true
Style/FileNull: # new in 1.69
  Enabled: true
Style/FileRead: # new in 1.24
  Enabled: true
Style/FileTouch: # new in 1.69
  Enabled: true
Style/FileWrite: # new in 1.24
  Enabled: true
Style/HashConversion: # new in 1.10
  Enabled: true
Style/HashExcept: # new in 1.7
  Enabled: true
Style/HashFetchChain: # new in 1.75
  Enabled: true
Style/HashSlice: # new in 1.71
  Enabled: true
Style/IfWithBooleanLiteralBranches: # new in 1.9
  Enabled: true
Style/InPatternThen: # new in 1.16
  Enabled: true
Style/ItAssignment: # new in 1.70
  Enabled: true
Style/ItBlockParameter: # new in 1.75
  Enabled: true
Style/KeywordArgumentsMerging: # new in 1.68
  Enabled: true
Style/MagicCommentFormat: # new in 1.35
  Enabled: true
Style/MapCompactWithConditionalBlock: # new in 1.30
  Enabled: true
Style/MapIntoArray: # new in 1.63
  Enabled: true
Style/MapToHash: # new in 1.24
  Enabled: true
Style/MapToSet: # new in 1.42
  Enabled: true
Style/MinMaxComparison: # new in 1.42
  Enabled: true
Style/MultilineInPatternThen: # new in 1.16
  Enabled: true
Style/NegatedIfElseCondition: # new in 1.2
  Enabled: true
Style/NestedFileDirname: # new in 1.26
  Enabled: true
Style/NilLambda: # new in 1.3
  Enabled: true
Style/NumberedParameters: # new in 1.22
  Enabled: true
Style/NumberedParametersLimit: # new in 1.22
  Enabled: true
Style/ObjectThen: # new in 1.28
  Enabled: true
Style/OpenStructUse: # new in 1.23
  Enabled: true
Style/OperatorMethodCall: # new in 1.37
  Enabled: true
Style/QuotedSymbols: # new in 1.16
  Enabled: true
Style/RedundantArgument: # new in 1.4
  Enabled: true
Style/RedundantArrayConstructor: # new in 1.52
  Enabled: true
Style/RedundantArrayFlatten: # new in 1.76
  Enabled: true
Style/RedundantConstantBase: # new in 1.40
  Enabled: true
Style/RedundantCurrentDirectoryInPath: # new in 1.53
  Enabled: true
Style/RedundantDoubleSplatHashBraces: # new in 1.41
  Enabled: true
Style/RedundantEach: # new in 1.38
  Enabled: true
Style/RedundantFilterChain: # new in 1.52
  Enabled: true
Style/RedundantFormat: # new in 1.72
  Enabled: true
Style/RedundantHeredocDelimiterQuotes: # new in 1.45
  Enabled: true
Style/RedundantInitialize: # new in 1.27
  Enabled: true
Style/RedundantInterpolationUnfreeze: # new in 1.66
  Enabled: true
Style/RedundantLineContinuation: # new in 1.49
  Enabled: true
Style/RedundantRegexpArgument: # new in 1.53
  Enabled: true
Style/RedundantRegexpConstructor: # new in 1.52
  Enabled: true
Style/RedundantSelfAssignmentBranch: # new in 1.19
  Enabled: true
Style/RedundantStringEscape: # new in 1.37
  Enabled: true
Style/ReturnNilInPredicateMethodDefinition: # new in 1.53
  Enabled: true
Style/SafeNavigationChainLength: # new in 1.68
  Enabled: true
Style/SelectByRegexp: # new in 1.22
  Enabled: true
Style/SendWithLiteralMethodName: # new in 1.64
  Enabled: true
Style/SingleLineDoEndBlock: # new in 1.57
  Enabled: true
Style/StringChars: # new in 1.12
  Enabled: true
Style/SuperArguments: # new in 1.64
  Enabled: true
Style/SuperWithArgsParentheses: # new in 1.58
  Enabled: true
Style/SwapValues: # new in 1.1
  Enabled: true
Style/YAMLFileRead: # new in 1.53
  Enabled: true
For more information: https://docs.rubocop.org/rubocop/versioning.html
Skipping parallel inspection: only a single file needs inspection
Inspecting 1 file
Scanning /Users/pat/Downloads/parentheses/parentheses.rb
Loading cache from /Users/pat/.cache/501/rubocop_cache/de410dfc80d41fc689ff490bc6b697f3803fda08/cd1b15cc92db741532719d887003a0dabf4dcfb9/35a054c815e32dc8bab6ded3662aa54877e89692
F

Offenses:

parentheses.rb:1:8: C: [Corrected] Style/RedundantParentheses: Don't use parentheses around a one-line rescue.
unless (Integer("foo") rescue nil)
       ^^^^^^^^^^^^^^^^^^^^^^^^^^^
parentheses.rb:1:23: F: Lint/Syntax: unexpected token kRESCUE_MOD
(Using Ruby 2.7 parser; configure using TargetRubyVersion parameter, under AllCops)
unless Integer("foo") rescue nil
                      ^^^^^^
parentheses.rb:3:1: F: Lint/Syntax: unexpected token kEND
(Using Ruby 2.7 parser; configure using TargetRubyVersion parameter, under AllCops)
end
^^^

1 file inspected, 3 offenses detected, 1 offense corrected
Finished in 0.16278100002091378 seconds

After:

$ cat parentheses.rb 
unless Integer("foo") rescue nil
  puts '"foo" is not an Integer'
end
$ ruby parentheses.rb 
parentheses.rb: --> parentheses.rb

expected `then` or `;` or '\n'
unexpected 'rescue' modifier, ignoring it

> 1  unless Integer("foo") rescue nil
> 3  end

parentheses.rb:1: syntax errors found (SyntaxError)
> 1 | unless Integer("foo") rescue nil
    |                       ^~~~~~ unexpected 'rescue' modifier, ignoring it
    |                       ^~~~~~ expected `then` or `;` or '\n'
  2 |   puts '"foo" is not an Integer'
  3 | end

Steps to reproduce the problem

See above.

RuboCop version

$ rubocop -V
1.80.2 (using Parser 3.3.9.0, rubocop-ast 1.47.1, analyzing as Ruby 2.7, running on ruby 3.4.1) [x86_64-darwin24]

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