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Merged
merged 2 commits into from
Mar 9, 2023
Merged

Add support for creating a macro package #6250

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eebf869
Add support for creating a macro package
DougGregor Mar 9, 2023
5404f93
Address review feedback
DougGregor Mar 9, 2023
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1 change: 1 addition & 0 deletions Sources/Commands/PackageTools/Init.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -31,6 +31,7 @@ extension SwiftPackageTool {
tool - A package with an executable that uses
Swift Argument Parser. Use this template if you
plan to have a rich set of command-line arguments.
macro - A package that vends a macro.
empty - An empty package with a Package.swift manifest.
"""))
var initMode: InitPackage.PackageType = .library
Expand Down
214 changes: 211 additions & 3 deletions Sources/Workspace/InitPackage.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -45,6 +45,7 @@ public final class InitPackage {
case executable = "executable"
case tool = "tool"
case `extension` = "extension"
case macro = "macro"

public var description: String {
return rawValue
Expand Down Expand Up @@ -135,6 +136,16 @@ public final class InitPackage {

import PackageDescription

"""

if packageType == .macro {
stream <<< """
import CompilerPluginSupport

"""
}

stream <<< """
let package = Package(

"""
Expand All @@ -144,8 +155,29 @@ public final class InitPackage {
name: "\(pkgname)"
""")

var platforms = options.platforms

// Macros require macOS 10.15, iOS 13, etc.
if packageType == .macro {
func addIfMissing(_ newPlatform: SupportedPlatform) {
if platforms.contains(where: { platform in
platform.platform == newPlatform.platform
}) {
return
}

platforms.append(newPlatform)
}

addIfMissing(.init(platform: .macOS, version: .init("10.15")))
addIfMissing(.init(platform: .iOS, version: .init("13")))
addIfMissing(.init(platform: .tvOS, version: .init("13")))
addIfMissing(.init(platform: .watchOS, version: .init("6")))
addIfMissing(.init(platform: .macCatalyst, version: .init("13")))
}

var platformsParams = [String]()
for supportedPlatform in options.platforms {
for supportedPlatform in platforms {
let version = supportedPlatform.version
let platform = supportedPlatform.platform

Expand All @@ -165,7 +197,7 @@ public final class InitPackage {
}

// Package platforms
if !options.platforms.isEmpty {
if !platforms.isEmpty {
pkgParams.append("""
platforms: [\(platformsParams.joined(separator: ", "))]
""")
Expand All @@ -181,6 +213,20 @@ public final class InitPackage {
targets: ["\(pkgname)"]),
]
""")
} else if packageType == .macro {
pkgParams.append("""
products: [
// Products define the executables and libraries a package produces, making them visible to other packages.
.library(
name: "\(pkgname)",
targets: ["\(pkgname)"]),
.executable(
name: "\(pkgname)Client",
targets: ["\(pkgname)Client"]
),
]
""")

}

// Package dependencies
Expand All @@ -190,6 +236,12 @@ public final class InitPackage {
.package(url: "https://github.com/apple/swift-argument-parser.git", from: "1.2.0"),
]
""")
} else if packageType == .macro {
pkgParams.append("""
dependencies: [
.package(url: "https://github.com/apple/swift-syntax.git", branch: "main"),
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We should make sure to have a follow-up task to change this from main once we have a concrete version that people should be using.

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Right. We should get that once we branch for Swift 5.9.

]
""")
}

// Package targets
Expand Down Expand Up @@ -219,6 +271,32 @@ public final class InitPackage {
path: "Sources"),
]
"""
} else if packageType == .macro {
param += """
// Macro implementation, only built for the host and never part of a client program.
.macro(name: "\(pkgname)Macros",
dependencies: [
.product(name: "SwiftSyntaxMacros", package: "swift-syntax"),
.product(name: "SwiftCompilerPlugin", package: "swift-syntax"),
]
),

// Library that exposes a macro as part of its API, which is used in client programs.
.target(name: "\(pkgname)", dependencies: ["\(pkgname)Macros"]),

// A client of the library, which is able to use the macro in its
// own code.
.executableTarget(name: "\(pkgname)Client", dependencies: ["\(pkgname)"]),

// A test target used to develop the macro implementation.
.testTarget(
name: "\(pkgname)Tests",
dependencies: [
"\(pkgname)Macros",
]
),
]
"""
} else {
param += """
.target(
Expand All @@ -239,7 +317,8 @@ public final class InitPackage {
// Create a tools version with current version but with patch set to zero.
// We do this to avoid adding unnecessary constraints to patch versions, if
// the package really needs it, they should add it manually.
let version = InitPackage.newPackageToolsVersion.zeroedPatch
let version = packageType == .macro ? ToolsVersion.vNext
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Also something to keep in mind to update later.

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Right, we'll update this when the macro target gets a proper Swift version instead of 999.

: InitPackage.newPackageToolsVersion.zeroedPatch

// Write the current tools version.
try ToolsVersionSpecificationWriter.rewriteSpecification(
Expand Down Expand Up @@ -331,13 +410,33 @@ public final class InitPackage {
}
}
"""
case .macro:
content = """
// The Swift Programming Language
// https://docs.swift.org/swift-book
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Maybe a more concrete reference to macros once we have it?

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Yes, makes sense


// A macro that produces both a value and a string containing the
// source code that generated the value. For example,
//
// #stringify(x + y)
//
// produces a tuple `(x + y, "x + y")`.
@freestanding(expression)
public macro stringify<T>(_ value: T) -> (T, String) = #externalMacro(module: "\(moduleName)Macros", type: "StringifyMacro")
"""

case .empty, .`extension`:
throw InternalError("invalid packageType \(packageType)")
}

try writePackageFile(sourceFile) { stream in
stream.write(content)
}

if packageType == .macro {
try writeMacroPluginSources(sources.appending("\(pkgname)Macros"))
try writeMacroClientSources(sources.appending("\(pkgname)Client"))
}
}

private func writeTests() throws {
Expand Down Expand Up @@ -374,6 +473,113 @@ public final class InitPackage {
}
}

private func writeMacroTestsFile(_ path: AbsolutePath) throws {
try writePackageFile(path) { stream in
stream <<< ##"""
import SwiftSyntax
import SwiftSyntaxBuilder
import SwiftSyntaxMacros
import XCTest
import \##(moduleName)Macros

var testMacros: [String: Macro.Type] = [
"stringify" : StringifyMacro.self,
]

final class \##(moduleName)Tests: XCTestCase {
func testMacro() {
// XCTest Documentation
// https://developer.apple.com/documentation/xctest

// Test input is a source file containing uses of the macro.
let sf: SourceFileSyntax =
#"""
let a = #stringify(x + y)
let b = #stringify("Hello, \(name)")
"""#
let context = BasicMacroExpansionContext.init(
sourceFiles: [sf: .init(moduleName: "MyModule", fullFilePath: "test.swift")]
)

// Expand the macro to produce a new source file with the
// result of the expansion, and ensure that it has the
// expected source code.
let transformedSF = sf.expand(macros: testMacros, in: context)
XCTAssertEqual(
transformedSF.description,
#"""
let a = (x + y, "x + y")
let b = ("Hello, \(name)", #""Hello, \(name)""#)
"""#
)
}
}

"""##
}
}

private func writeMacroPluginSources(_ path: AbsolutePath) throws {
try makeDirectories(path)

try writePackageFile(path.appending("\(moduleName)Macro.swift")) { stream in
stream <<< ##"""
import SwiftCompilerPlugin
import SwiftSyntax
import SwiftSyntaxBuilder
import SwiftSyntaxMacros

/// Implementation of the `stringify` macro, which takes an expression
/// of any type and produces a tuple containing the value of that expression
/// and the source code that produced the value. For example
///
/// #stringify(x + y)
///
/// will expand to
///
/// (x + y, "x + y")
public struct StringifyMacro: ExpressionMacro {
public static func expansion(
of node: some FreestandingMacroExpansionSyntax,
in context: some MacroExpansionContext
) -> ExprSyntax {
guard let argument = node.argumentList.first?.expression else {
fatalError("compiler bug: the macro does not have any arguments")
}

return "(\(argument), \(literal: argument.description))"
}
}

@main
struct \##(moduleName)Plugin: CompilerPlugin {
let providingMacros: [Macro.Type] = [
StringifyMacro.self,
]
}

"""##
}
}

private func writeMacroClientSources(_ path: AbsolutePath) throws {
try makeDirectories(path)

try writePackageFile(path.appending("main.swift")) { stream in
stream <<< ##"""
import \##(moduleName)

let a = 17
let b = 25

let (result, code) = #stringify(a + b)

print("The value \(result) was produced by the code \"\(code)\"")

"""##
}
}

private func writeTestFileStubs(testsPath: AbsolutePath) throws {
let testModule = try AbsolutePath(validating: pkgname + Target.testModuleNameSuffix, relativeTo: testsPath)
progressReporter?("Creating \(testModule.relative(to: destinationPath))/")
Expand All @@ -384,6 +590,8 @@ public final class InitPackage {
case .empty, .`extension`, .executable, .tool: break
case .library:
try writeLibraryTestsFile(testClassFile)
case .macro:
try writeMacroTestsFile(testClassFile)
}
}
}
Expand Down