Swift: Add more tests for String flow sources.

Author: geoffw0

swift/ql/test/library-tests/dataflow/flowsources/FlowSources.expected

@@ -3,8 +3,8 @@
 | customurlschemes.swift:38:52:38:62 | url | external |
 | customurlschemes.swift:43:9:43:28 | ...[...] | Remote URL in UIApplicationDelegate.application.launchOptions |
 | customurlschemes.swift:48:9:48:28 | ...[...] | Remote URL in UIApplicationDelegate.application.launchOptions |
-| string.swift:27:21:27:21 | call to init(contentsOf:) | external |
-| string.swift:27:21:27:44 | call to init(contentsOf:) | external |
+| string.swift:56:21:56:21 | call to init(contentsOf:) | external |
+| string.swift:56:21:56:44 | call to init(contentsOf:) | external |
 | url.swift:53:15:53:19 | .resourceBytes | external |
 | url.swift:60:15:60:19 | .lines | external |
 | url.swift:67:16:67:22 | .lines | external |

swift/ql/test/library-tests/dataflow/flowsources/string.swift

@@ -7,13 +7,41 @@ struct URL
 }
 
 extension String {
-	init(contentsOf: URL) throws {
+	struct Encoding {
+		var rawValue: UInt
+
+		init(rawValue: UInt) { self.rawValue = rawValue }
+
+		static let ascii = Encoding(rawValue: 1)
+	}
+
+	init(contentsOf url: URL) throws {
 		var data = ""
 
 		// ...
 
 		self.init(data)
 	}
+
+	init(contentsOf url: URL, encoding enc: String.Encoding) throws {
+		self.init("")
+	}
+
+	init(contentsOf url: URL, usedEncoding: inout String.Encoding) throws {
+		self.init("")
+	}
+
+	init(contentsOfFile path: String) throws {
+		self.init("")
+	}
+
+	init(contentsOfFile path: String, encoding enc: String.Encoding) throws {
+		self.init("")
+	}
+
+	init(contentsOfFile path: String, usedEncoding: inout String.Encoding) throws {
+		self.init("")
+	}
 }
 
 // --- tests ---
@@ -23,8 +51,17 @@ func testStrings() {
 	{
 		let string1 = String()
 		let string2 = String(repeating: "abc", count: 10)
+
 		let url = URL(string: "http://example.com/")
 		let string3 = try String(contentsOf: url!) // SOURCE
+		let string4 = try String(contentsOf: url!, encoding: String.Encoding.ascii) // SOURCE [NOT DETECTED]
+		var encoding = String.Encoding.ascii
+		let string5 = try String(contentsOf: url!, usedEncoding: &encoding) // SOURCE [NOT DETECTED]
+
+		let path = "file.txt"
+		let string6 = try String(contentsOfFile: path) // SOURCE [NOT DETECTED]
+		let string7 = try String(contentsOfFile: path, encoding: String.Encoding.ascii) // SOURCE [NOT DETECTED]
+		let string8 = try String(contentsOfFile: path, usedEncoding: &encoding) // SOURCE [NOT DETECTED]
 	} catch {
 		// ...
 	}