mattgallagher

//
//  ContentView.swift
//  Layout
//
//  Created by Matt Gallagher on 7/6/19.
//  Copyright © 2019 Matt Gallagher. All rights reserved.
//

import SwiftUI

anandabits

func testIsBidirectional() {
    func assert<C: Collection>(_ collection: C, isBidirectional: Bool) {
        XCTAssertEqual(collection.isBidirectional, isBidirectional)
    }

    assert([1, 2, 3], isBidirectional: true)
    assert(Set([1, 2, 3]), isBidirectional: false)
}

extension Collection {

dabrahams

/// A repository of functionality depending on the conformances of `Model`.
///
/// Conditional conformances provide implementation functions that take a
/// generic argument type with the safe assumption that the argument's concrete
/// type is `Model`.
struct Dispatch<Model> {
  /// Returns `f(a as! Model) as! R1`
  ///
  /// Used by implementation functions to avoid the clutter of casting
  /// explicitly.

dabrahams

/// Classes whose initializers actually create derived classes
protocol FactoryInitializable {
  /// The type of the least-derived class declared to be FactoryInitializable.
  ///
  /// - Warning: Do not define this in your FactoryInitializable type!
  associatedtype FactoryBase: AnyObject, FactoryInitializable = Self
  // This associatedtype is a trick that captures `Self` at the point where
  // `FactoryInitializable` enters a class hierarchy; in other contexts, `Self`
  // refers to the most-derived type.
}

jegnux

import SwiftUI
import Combine

public struct ChangeObserver<V: Equatable>: ViewModifier {
    public init(newValue: V, action: @escaping (V) -> Void) {
        self.newValue = newValue
        self.newAction = action
    }

    private typealias Action = (V) -> Void

schwa

Using LLVM's libfuzzer with Swift

Background

Of the many tools available for fuzzing, I've found that LLVM's libfuzzer is the easiest to use for Swift on macOS. Other tools seem to have a list of requirements taht are difficult to meet. libfuzzer on the other hand is built into LLVM and is available on macOS in the custom Swift toolchains: https://www.swift.org/download/

In this document I'll describe how to use libfuzzer with Swift and Swift Packages.

I used this setup to fuzz an SVG Renderer package that I am building. I was able to find and fix a number of bugs in my SVG parsing code using libfuzzer in basically no time at all.