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Bazel Xcode Demo

This is a demo of Bazel and Xcode integration. This isn't an actual fork of apple/swift-driver.

See bazel/README.md for specifics.

Trying The Demo

First, install Bazel and XcodeGen.

If you're using brew, a simple way to install is:

brew tap bazelbuild/tap
brew install bazelbuild/tap/bazel
brew install XcodeGen

Once installed, generate and open the Xcode project by running:

make project
open swift-driver.xcodeproj

For debugging to work, an lldb settings file is generated. In your ~/.lldbinit, add this line:

command source ~/.lldbinit-source-map

Swift Compiler Driver

Swift's compiler driver is a program that coordinates the compilation of Swift source code into various compiled results: executables, libraries, object files, Swift modules and interfaces, etc. It is the program one invokes from the command line to build Swift code (i.e., swift or swiftc) and is often invoked on the developer's behalf by a build system such as the Swift Package Manager (SwiftPM) or Xcode's build system.

The swift-driver project is a new implementation of the Swift compiler driver that is intended to replace the existing driver with a more extensible, maintainable, and robust code base. The specific goals of this project include:

Getting Started

Use the Swift package manager to build swift-driver:

$ swift build

To use swift-driver in place of the existing Swift driver, create a symbolic link from swift and swiftc to swift-driver:

ln -s /path/to/built/swift-driver $SOME_PATH/swift
ln -s /path/to/built/swift-driver $SOME_PATH/swiftc

Swift packages can be built with the new Swift driver by overriding SWIFT_EXEC to refer to the swiftc symbolic link created above, e.g.,

SWIFT_EXEC=$SOME_PATH/swiftc swift build

Similarly, one can use the new Swift driver within Xcode by adding a custom build setting (usually at the project level) named SWIFT_EXEC that refers to $SOME_PATH/swiftc.

Developing swift-driver

The new Swift driver is a work in progress, and there are numerous places for anyone with an interest to contribute! This section covers testing, miscellaneous development tips and tricks, and a rough development plan showing what work still needs to be done.

Driver Documentation

For a conceptual overview of the driver, see The Swift Driver, Compilation Model, and Command-Line Experience. To learn more about the internals, see Driver Design & Internals and Parseable Driver Output.

Testing

Test using command-line SwiftPM or Xcode.

$ swift test --parallel

Integration tests are costly to run and are disabled by default. Enable them using SWIFT_DRIVER_ENABLE_INTEGRATION_TESTS environment variable. In Xcode, you can set this variable in the scheme's test action.

$ SWIFT_DRIVER_ENABLE_INTEGRATION_TESTS=1 swift test --parallel

Some integration tests run the lit test suites in a Swift working copy. To enable these, clone Swift and its dependencies and build them with build-script, then set both SWIFT_DRIVER_ENABLE_INTEGRATION_TESTS and SWIFT_DRIVER_LIT_DIR, either in your Xcode scheme or on the command line:

$ SWIFT_DRIVER_ENABLE_INTEGRATION_TESTS=1 \
  SWIFT_DRIVER_LIT_DIR=/path/to/build/Ninja-ReleaseAssert/swift-.../test-... \
  swift test --parallel

Preparing a Linux docker for debug

When developing on macOS without quick access to a Linux machine, using a Linux Docker is often helpful when debugging.

To get a docker up and running to the following:

$ docker run -v /path/to/swift-driver:/home/swift-driver \
  --cap-add=SYS_PTRACE --security-opt seccomp=unconfined \
  --security-opt apparmor=unconfined -it swift:latest bash

$ apt-get update
$ apt-get install libsqlite3-dev
$ apt-get install libncurses-dev

Rebuilding Options.swift

Options.swift, which contains the complete set of options that can be parsed by the driver, is automatically generated from the option tables in the Swift compiler. If you need to regenerate Options.swift, you will need to build the Swift compiler and then build makeOptions program with a -I that allows the generated Options.inc to be found, e.g.:

$ swift build -Xcc -I/path/to/build/Ninja-ReleaseAssert/swift-.../include --product makeOptions

Then, run makeOptions and redirect the output to overwrite Options.swift:

$ .build/path/to/makeOptions > Sources/SwiftDriver/Options/Options.swift

Development Plan

The goal of the new Swift driver is to provide a drop-in replacement for the existing driver, which means that there is a fixed initial feature set to implement before the existing Swift driver can be deprecated and removed. The development plan below covers that feature set, as well as describing a number of tasks that can improve the Swift driver---from code cleanups, to improving testing, implementing missing features, and integrating with existing systems.