Add include_variables option to non_optional_string_data_conversion rule (#6172)

Co-authored-by: Danny Mösch <danny.moesch@icloud.com>

CHANGELOG.md

@@ -22,6 +22,12 @@
 
 ### Enhancements
 
+* Add `include_variables` configuration option to `non_optional_string_data_conversion` rule.  
+  When enabled, the rule will trigger on variables, properties, and function calls in addition
+  to string literals. Defaults to `false` for backward compatibility.  
+  [SimplyDanny](https://github.com/SimplyDanny)
+  [#6094](https://github.com/realm/SwiftLint/issues/6094)
+
 * Add Sendable conformance to Rule.Type for building with Swift 6.  
   [erikkerber](https://github.com/erikkerber)
   [#issue_number](https://github.com/realm/SwiftLint/issues/issue_number)

Source/SwiftLintBuiltInRules/Rules/Lint/NonOptionalStringDataConversionRule.swift

@@ -1,18 +1,35 @@
+import SwiftLintCore
 import SwiftSyntax
 
 @SwiftSyntaxRule
 struct NonOptionalStringDataConversionRule: Rule {
-    var configuration = SeverityConfiguration<Self>(.warning)
+    var configuration = NonOptionalStringDataConversionConfiguration()
+
+    private static let variablesIncluded = ["include_variables": true]
+
     static let description = RuleDescription(
         identifier: "non_optional_string_data_conversion",
         name: "Non-optional String -> Data Conversion",
         description: "Prefer non-optional `Data(_:)` initializer when converting `String` to `Data`",
         kind: .lint,
         nonTriggeringExamples: [
-            Example("Data(\"foo\".utf8)")
+            Example("Data(\"foo\".utf8)"),
+            Example("Data(string.utf8)"),
+            Example("\"foo\".data(using: .ascii)"),
+            Example("string.data(using: .unicode)"),
+            Example("Data(\"foo\".utf8)", configuration: variablesIncluded),
+            Example("Data(string.utf8)", configuration: variablesIncluded),
+            Example("\"foo\".data(using: .ascii)", configuration: variablesIncluded),
+            Example("string.data(using: .unicode)", configuration: variablesIncluded),
         ],
         triggeringExamples: [
-            Example("\"foo\".data(using: .utf8)")
+            Example("↓\"foo\".data(using: .utf8)"),
+            Example("↓\"foo\".data(using: .utf8)", configuration: variablesIncluded),
+            Example("↓string.data(using: .utf8)", configuration: variablesIncluded),
+            Example("↓property.data(using: .utf8)", configuration: variablesIncluded),
+            Example("↓obj.property.data(using: .utf8)", configuration: variablesIncluded),
+            Example("↓getString().data(using: .utf8)", configuration: variablesIncluded),
+            Example("↓getValue()?.data(using: .utf8)", configuration: variablesIncluded),
         ]
     )
 }
@@ -20,12 +37,13 @@ struct NonOptionalStringDataConversionRule: Rule {
 private extension NonOptionalStringDataConversionRule {
     final class Visitor: ViolationsSyntaxVisitor<ConfigurationType> {
         override func visitPost(_ node: MemberAccessExprSyntax) {
-            if node.base?.is(StringLiteralExprSyntax.self) == true,
-               node.declName.baseName.text == "data",
+            if node.declName.baseName.text == "data",
                let parent = node.parent?.as(FunctionCallExprSyntax.self),
                let argument = parent.arguments.onlyElement,
                argument.label?.text == "using",
-               argument.expression.as(MemberAccessExprSyntax.self)?.isUTF8 == true {
+               argument.expression.as(MemberAccessExprSyntax.self)?.isUTF8 == true,
+               let base = node.base,
+               base.is(StringLiteralExprSyntax.self) || configuration.includeVariables {
                 violations.append(node.positionAfterSkippingLeadingTrivia)
             }
         }

Source/SwiftLintBuiltInRules/Rules/RuleConfigurations/NonOptionalStringDataConversionConfiguration.swift

@@ -0,0 +1,12 @@
+import SwiftLintCore
+
+@AutoConfigParser
+struct NonOptionalStringDataConversionConfiguration: SeverityBasedRuleConfiguration {
+    // swiftlint:disable:previous type_name
+    typealias Parent = NonOptionalStringDataConversionRule
+
+    @ConfigurationElement(key: "severity")
+    private(set) var severityConfiguration = SeverityConfiguration<Parent>(.warning)
+    @ConfigurationElement(key: "include_variables")
+    private(set) var includeVariables = false
+}

Tests/IntegrationTests/default_rule_configurations.yml

@@ -737,6 +737,7 @@ no_space_in_method_call:
     correctable: true
 non_optional_string_data_conversion:
   severity: warning
+  include_variables: false
   meta:
     opt-in: false
     correctable: false