Merge pull request #555 from drexin/wip-static-linking

Use library search group when linking statically

Author: drexin

Sources/SwiftDriver/Jobs/GenericUnixToolchain+LinkerSupport.swift

@@ -152,6 +152,14 @@ extension GenericUnixToolchain {
         )
       commandLine.appendPath(swiftrtPath)
 
+      // If we are linking statically, we need to add all
+      // dependencies to a library search group to resolve
+      // potential circular dependencies
+      if staticStdlib || staticExecutable {
+        commandLine.appendFlag(.Xlinker)
+        commandLine.appendFlag("--start-group")
+      }
+
       let inputFiles: [Job.ArgTemplate] = inputs.compactMap { input in
         // Autolink inputs are handled specially
         if input.type == .autolink {
@@ -166,6 +174,11 @@ extension GenericUnixToolchain {
       }
       commandLine.append(contentsOf: inputFiles)
 
+      if staticStdlib || staticExecutable {
+        commandLine.appendFlag(.Xlinker)
+        commandLine.appendFlag("--end-group")
+      }
+
       let fSystemArgs = parsedOptions.arguments(for: .F, .Fsystem)
       for opt in fSystemArgs {
         if opt.option == .Fsystem {

Tests/SwiftDriverTests/SwiftDriverTests.swift

@@ -1289,8 +1289,43 @@ final class SwiftDriverTests: XCTestCase {
       XCTAssertFalse(cmd.contains(.flag("-dylib")))
       XCTAssertFalse(cmd.contains(.flag("-static")))
       XCTAssertFalse(cmd.contains(.flag("-shared")))
+      XCTAssertFalse(cmd.contains(.flag("--start-group")))
+      XCTAssertFalse(cmd.contains(.flag("--end-group")))
     }
 
+    // /usr/lib/swift_static/linux/static-stdlib-args.lnk is required for static
+    // linking on Linux, but is not present in macOS toolchains
+    #if os(Linux)
+    do {
+      // executable linking linux static stdlib
+      var driver = try Driver(args: commonArgs + ["-emit-executable", "-static-stdlib", "-target", "x86_64-unknown-linux"], env: env)
+      let plannedJobs = try driver.planBuild()
+
+      XCTAssertEqual(plannedJobs.count, 4)
+
+      let autolinkExtractJob = plannedJobs[2]
+      XCTAssertEqual(autolinkExtractJob.kind, .autolinkExtract)
+
+      let autolinkCmd = autolinkExtractJob.commandLine
+      XCTAssertTrue(autolinkCmd.contains(.path(.temporary(RelativePath("foo.o")))))
+      XCTAssertTrue(autolinkCmd.contains(.path(.temporary(RelativePath("bar.o")))))
+      XCTAssertTrue(autolinkCmd.contains(.path(.temporary(RelativePath("Test.autolink")))))
+
+      let linkJob = plannedJobs[3]
+      let cmd = linkJob.commandLine
+      XCTAssertTrue(cmd.contains(.flag("-o")))
+      XCTAssertTrue(cmd.contains(.path(.temporary(RelativePath("foo.o")))))
+      XCTAssertTrue(cmd.contains(.path(.temporary(RelativePath("bar.o")))))
+      XCTAssertTrue(cmd.contains(.flag("--start-group")))
+      XCTAssertTrue(cmd.contains(.flag("--end-group")))
+      XCTAssertEqual(linkJob.outputs[0].file, try VirtualPath(path: "Test"))
+
+      XCTAssertFalse(cmd.contains(.flag("-static")))
+      XCTAssertFalse(cmd.contains(.flag("-dylib")))
+      XCTAssertFalse(cmd.contains(.flag("-shared")))
+    }
+    #endif
+
     do {
       // static WASM linking
       var driver = try Driver(args: commonArgs + ["-emit-library", "-static", "-target", "wasm32-unknown-wasi"], env: env)