Invalid trigger for unused_closure_parameter when parameter is used in string interpolation

[JRHeaton]

New Issue Checklist

• Updated SwiftLint to the latest version
• I searched for existing GitHub issues

Bug Report

Complete output when running SwiftLint, including the stack trace and command used

~> swiftlint lint
Loading configuration from '.swiftlint.yml'
Linting Swift files in current working directory
# ... non problematic files
/.../Mapper.swift:53:31: warning: Unused Closure Parameter Violation: Unused parameter "input" in a closure should be replaced with _. (unused_closure_parameter)
/.../Mapper.swift:53:38: warning: Unused Closure Parameter Violation: Unused parameter "context" in a closure should be replaced with _. (unused_closure_parameter)
/.../Mapper.swift:53:47: warning: Unused Closure Parameter Violation: Unused parameter "output" in a closure should be replaced with _. (unused_closure_parameter)
Done linting! Found 3 violations, 0 serious in 37 files.

Environment

• SwiftLint version (run swiftlint version to be sure)?

~> swiftlint version
0.25.0

• Installation method used (Homebrew, CocoaPods, building from source, etc)?
  Homebrew
• Paste your configuration file:

included:
  - Sources

opt_in_rules:
  - array_init
  - attributes
  - closure_end_indentation
  - closure_spacing
  - conditional_returns_on_newline
  - contains_over_first_not_nil
  - empty_count
  - explicit_enum_raw_value
  - explicit_init
  - explicit_top_level_acl
  - explicit_type_interface
  - extension_access_modifier
  - fatal_error_message
  - first_where
  - force_unwrapping
  - implicitly_unwrapped_optional
  - joined_default_parameter
  - let_var_whitespace
  - literal_expression_end_indentation
  - multiline_arguments
  - multiline_parameters
  - nimble_operator
  - no_extension_access_modifier
  - no_grouping_extension
  - number_separator
  - object_literal
  - operator_usage_whitespace
  - overridden_super_call
  - pattern_matching_keywords
  - private_outlet
  - prohibited_super_call
  - quick_discouraged_call
  - redundant_nil_coalescing
  - single_test_class
  - sorted_imports
  - strict_fileprivate
  - switch_case_on_newline
  - trailing_closure
  - unneeded_parentheses_in_closure_argument
  - vertical_parameter_alignment_on_call

disabled_rules:
  - extension_access_modifier
  - explicit_enum_raw_value
  - void_return
  - explicit_type_interface
  - number_separator
  - trailing_whitespace
  - function_body_length
  - line_length
  - redundant_optional_initialization
  - explicit_top_level_acl
  - identifier_name
  - no_grouping_extension

nesting:
  type_level: 2

colon:
  apply_to_dictionaries: false

statement_position:
  statement_mode: uncuddled_else

• Are you using nested configurations?
  If so, paste their relative paths and respective contents.

No

• Which Xcode version are you using (check xcode-select -p)?

~> xcode-select -p
/Applications/Xcode.app/Contents/Developer

As the title state, the rule doesn't appear to see the variables referenced via string interpolation in the scope of this function.

[marcelofabri]

Please paste the source code in the future instead of attaching a screenshot 😉

[JRHeaton]

🤔 I deliberately chose to post screenshots, as source code snippets aren’t going to show the Xcode error. I am mobile now but if it’s necessary for some reason I have no problem posting the code when I’m back at a computer.

EDIT:

extension Mapper {
	func withPrinting(
		input printInput: Bool = true,
		context printContext: Bool = true,
		output printOutput: Bool = true,
		includeTypeNames: Bool = false
	) -> Mapper {
		return withPostSideEffect { input, context, output in
			if printInput { print("Input: \(includeTypeNames ? String(describing: type(of: input)).appending(".") : "")\(input)") }
			if printContext { print("Context: \(includeTypeNames ? String(describing: type(of: context)).appending(".") : "")\(context)") }
			if printOutput { print("Output: \(includeTypeNames ? String(describing: type(of: output)).appending(".") : "")\(output)") }
		}
	}
}

[marcelofabri]

@JRHeaton Are you sure you're using Xcode 9.2 / Swift 4.0 toolchain? I only was able to reproduce this with Xcode 9.3 beta.