[Build] Link static swift stdlib by default on macOS

Sources/Build/BuildPlan.swift

@@ -66,18 +66,23 @@ public struct BuildParameters {
     /// The tools version to use.
     public let toolsVersion: ToolsVersion
 
+    /// If should link the Swift stdlib statically.
+    public let shouldLinkStaticSwiftStdlib: Bool
+
     public init(
         dataPath: AbsolutePath,
         configuration: Configuration,
         toolchain: Toolchain,
         flags: BuildFlags,
-        toolsVersion: ToolsVersion = ToolsVersion.currentToolsVersion
+        toolsVersion: ToolsVersion = ToolsVersion.currentToolsVersion,
+        shouldLinkStaticSwiftStdlib: Bool = false
     ) {
         self.dataPath = dataPath
         self.configuration = configuration
         self.toolchain = toolchain
         self.flags = flags
         self.toolsVersion = toolsVersion
+        self.shouldLinkStaticSwiftStdlib = shouldLinkStaticSwiftStdlib
     }
 }
 
@@ -390,6 +395,13 @@ public final class ProductBuildDescription {
         case .library(.dynamic):
             args += ["-emit-library"]
         case .executable:
+            // Link the Swift stdlib statically if requested.
+            if buildParameters.shouldLinkStaticSwiftStdlib {
+                // FIXME: This does not work for linux yet (SR-648).
+              #if os(macOS)
+                args += ["-static-stdlib"]
+              #endif
+            }
             args += ["-emit-executable"]
         }
         args += objects.map({ $0.asString })

Sources/Commands/Options.swift

@@ -43,5 +43,8 @@ public class ToolOptions {
     /// Path to the compilation destination describing JSON file.
     public var customCompileDestination: AbsolutePath?
 
+    /// If should link the Swift stdlib statically.
+    public var shouldLinkStaticSwiftStdlib = false
+
     public required init() {}
 }

Sources/Commands/SwiftTool.swift

@@ -205,6 +205,16 @@ public class SwiftTool<Options: ToolOptions> {
                 usage: "Increase verbosity of informational output"),
             to: { $0.verbosity = $1 ? 1 : 0 })
 
+        binder.bind(
+            option: parser.add(option: "--no-static-swift-stdlib", kind: Bool.self,
+                usage: "Do not link Swift stdlib statically"),
+            to: { $0.shouldLinkStaticSwiftStdlib = !$1 })
+
+        binder.bind(
+            option: parser.add(option: "--static-swift-stdlib", kind: Bool.self,
+                usage: "Link Swift stdlib statically"),
+            to: { $0.shouldLinkStaticSwiftStdlib = $1 })
+
         // Let subclasses bind arguments.
         type(of: self).defineArguments(parser: parser, binder: binder)
 
@@ -432,7 +442,9 @@ public class SwiftTool<Options: ToolOptions> {
                 dataPath: buildPath,
                 configuration: options.configuration,
                 toolchain: try getToolchain(),
-                flags: options.buildFlags),
+                flags: options.buildFlags,
+                shouldLinkStaticSwiftStdlib: options.shouldLinkStaticSwiftStdlib
+            ),
             graph: try loadPackageGraph(),
             delegate: self)
     }

Tests/BuildTests/BuildPlanTests.swift

@@ -38,12 +38,17 @@ private struct MockToolchain: Toolchain {
 
 final class BuildPlanTests: XCTestCase {
 
-    func mockBuildParameters(buildPath: AbsolutePath = AbsolutePath("/path/to/build"), config: Build.Configuration = .debug) -> BuildParameters {
+    func mockBuildParameters(
+        buildPath: AbsolutePath = AbsolutePath("/path/to/build"),
+        config: Build.Configuration = .debug,
+        shouldLinkStaticSwiftStdlib: Bool = false
+    ) -> BuildParameters {
         return BuildParameters(
             dataPath: buildPath,
             configuration: config,
             toolchain: MockToolchain(),
-            flags: BuildFlags())
+            flags: BuildFlags(),
+            shouldLinkStaticSwiftStdlib: shouldLinkStaticSwiftStdlib)
     }
 
     func testBasicSwiftPackage() throws {
@@ -59,7 +64,10 @@ final class BuildPlanTests: XCTestCase {
         )
         let diagnostics = DiagnosticsEngine()
         let graph = loadMockPackageGraph(["/Pkg": pkg], root: "/Pkg", diagnostics: diagnostics, in: fs)
-        let result = BuildPlanResult(plan: try BuildPlan(buildParameters: mockBuildParameters(), graph: graph))
+        let result = BuildPlanResult(plan: try BuildPlan(
+            buildParameters: mockBuildParameters(shouldLinkStaticSwiftStdlib: true),
+            graph: graph)
+        )
 
         result.checkProductsCount(1)
         result.checkTargetsCount(2)
@@ -70,12 +78,17 @@ final class BuildPlanTests: XCTestCase {
         let lib = try result.target(for: "lib").swiftTarget().compileArguments()
         XCTAssertEqual(lib, ["-swift-version", "3", "-Onone", "-g", "-enable-testing", "-j8", "-DSWIFT_PACKAGE", "-module-cache-path", "/path/to/build/debug/ModuleCache"])
 
-        XCTAssertEqual(try result.buildProduct(for: "exe").linkArguments(), ["/fake/path/to/swiftc", "-g", "-L", "/path/to/build/debug",
-            "-o", "/path/to/build/debug/exe", "-module-name", "exe", 
-            "-emit-executable",
+        var linkArguments = ["/fake/path/to/swiftc", "-g", "-L", "/path/to/build/debug",
+            "-o", "/path/to/build/debug/exe", "-module-name", "exe"]
+      #if os(macOS)
+        linkArguments += ["-static-stdlib"]
+      #endif
+        linkArguments += ["-emit-executable",
             "/path/to/build/debug/exe.build/main.swift.o",
             "/path/to/build/debug/lib.build/lib.swift.o",
-        ])
+        ]
+
+        XCTAssertEqual(try result.buildProduct(for: "exe").linkArguments(), linkArguments)
     }
 
     func testBasicReleasePackage() throws {