Make plugins codegen compatible with Swift 6

Author: MaxDesiatov

Fixtures/Miscellaneous/Plugins/MyBuildToolPluginDependencies/Sources/MySourceGenBuildTool/main.swift

@@ -13,6 +13,6 @@ let variableName = URL(fileURLWithPath: inputFile).deletingPathExtension().lastP
 
 let inputData = FileManager.default.contents(atPath: inputFile) ?? Data()
 let dataAsHex = inputData.map { String(format: "%02hhx", $0) }.joined()
-let outputString = "public var \(variableName) = \(dataAsHex.quotedForSourceCode)\n"
+let outputString = "public let \(variableName) = \(dataAsHex.quotedForSourceCode)\n"
 let outputData = outputString.data(using: .utf8)
 FileManager.default.createFile(atPath: outputFile, contents: outputData)

Fixtures/Miscellaneous/Plugins/MySourceGenPlugin/Sources/MySourceGenBuildTool/main.swift

@@ -13,6 +13,6 @@ let variableName = URL(fileURLWithPath: inputFile).deletingPathExtension().lastP
 
 let inputData = FileManager.default.contents(atPath: inputFile) ?? Data()
 let dataAsHex = inputData.map { String(format: "%02hhx", $0) }.joined()
-let outputString = "public var \(variableName) = \(dataAsHex.quotedForSourceCode)\n"
+let outputString = "public let \(variableName) = \(dataAsHex.quotedForSourceCode)\n"
 let outputData = outputString.data(using: .utf8)
 FileManager.default.createFile(atPath: outputFile, contents: outputData)

Fixtures/Miscellaneous/Plugins/MySourceGenPluginUsingURLBasedAPI/Sources/MySourceGenBuildTool/main.swift

@@ -13,6 +13,6 @@ let variableName = URL(fileURLWithPath: inputFile).deletingPathExtension().lastP
 
 let inputData = FileManager.default.contents(atPath: inputFile) ?? Data()
 let dataAsHex = inputData.map { String(format: "%02hhx", $0) }.joined()
-let outputString = "public var \(variableName) = \(dataAsHex.quotedForSourceCode)\n"
+let outputString = "public let \(variableName) = \(dataAsHex.quotedForSourceCode)\n"
 let outputData = outputString.data(using: .utf8)
 FileManager.default.createFile(atPath: outputFile, contents: outputData)

Fixtures/Miscellaneous/Plugins/PluginWithInternalExecutable/Sources/PluginExecutable/main.swift

@@ -12,6 +12,6 @@ let variableName = URL(fileURLWithPath: inputFile).deletingPathExtension().lastP
 
 let inputData = FileManager.default.contents(atPath: inputFile) ?? Data()
 let dataAsHex = inputData.map { String(format: "%02hhx", $0) }.joined()
-let outputString = "public var \(variableName) = \(dataAsHex.quotedForSourceCode)\n"
+let outputString = "public let \(variableName) = \(dataAsHex.quotedForSourceCode)\n"
 let outputData = outputString.data(using: .utf8)
 FileManager.default.createFile(atPath: outputFile, contents: outputData)