Fix: optional_data_string_conversion should detect String.init and leading-dot .init usages

[nadeemnali]

Summary

The optional_data_string_conversion SwiftSyntax rule only detected direct calls like:

String(decoding: data, as: UTF8.self)

but it missed two common variants:

• Type-qualified initializer: String.init(decoding: data, as: UTF8.self)
• Leading dot initializer used with an explicit type annotation: let text: String = .init(decoding: data, as: UTF8.self)

This change updates the rule to detect both String.init(...) and leading-dot .init(...) when the contextual type is String. It also adds examples to the rule description and a unit test that verifies the rule's description examples.

Changes

• Update OptionalDataStringConversionRule visitor to:
  • keep existing detection for direct String(...) calls,
  • detect String.init(...) (MemberAccessExpr with base String and member init),
  • detect leading-dot .init(...) when assigned to a variable with an explicit String type annotation.
• Add a test file which runs the rule's description examples.

Why

This fixes the bug reported where let text: String = .init(decoding: data, as: UTF8.self) did not produce the expected lint violation.

Test plan

• Unit test included: Tests/SwiftLintBuiltInRulesTests/OptionalDataStringConversionRuleTests.swift
• The test verifies the rule's nonTriggering and triggering examples contained in the RuleDescription.

[SwiftLintBot]

	1 Warning
:warning:	This PR may need tests.

	19 Messages
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