Fix incorrect link job options for embedded WASI (#1841)

`WebAssemblyToolchain` didn't check for `parsedOptions.isEmbeddedEnabled` when forming `swiftrt.o` and `static-executable-args.lnk` options, and neither of these files exist when building with Embedded Swift for WASI.

Author: MaxDesiatov

Sources/SwiftDriver/Jobs/WebAssemblyToolchain+LinkerSupport.swift

@@ -90,7 +90,7 @@ extension WebAssemblyToolchain {
         isShared: false
       )
 
-      if !parsedOptions.hasArgument(.nostartfiles) {
+      if !parsedOptions.hasArgument(.nostartfiles) && !parsedOptions.isEmbeddedEnabled {
         let swiftrtPath = VirtualPath.lookup(targetInfo.runtimeResourcePath.path)
           .appending(
             components: targetTriple.platformName() ?? "",
@@ -125,15 +125,17 @@ extension WebAssemblyToolchain {
         commandLine.appendPath(path)
       }
 
-      // Link the standard library and dependencies.
-      let linkFilePath: VirtualPath =
-          VirtualPath.lookup(targetInfo.runtimeResourcePath.path)
-              .appending(components: targetTriple.platformName() ?? "",
-                                     "static-executable-args.lnk")
-      guard try fileSystem.exists(linkFilePath) else {
-        throw Error.missingExternalDependency(linkFilePath.name)
+      if !parsedOptions.isEmbeddedEnabled {
+        // Link the standard library and dependencies.
+        let linkFilePath: VirtualPath =
+        VirtualPath.lookup(targetInfo.runtimeResourcePath.path)
+          .appending(components: targetTriple.platformName() ?? "",
+                     "static-executable-args.lnk")
+        guard try fileSystem.exists(linkFilePath) else {
+          throw Error.missingExternalDependency(linkFilePath.name)
+        }
+        commandLine.append(.responseFilePath(linkFilePath))
       }
-      commandLine.append(.responseFilePath(linkFilePath))
 
       // Pass down an optimization level
       if let optArg = mapOptimizationLevelToClangArg(from: &parsedOptions) {

Tests/SwiftDriverTests/SwiftDriverTests.swift

@@ -6861,6 +6861,23 @@ final class SwiftDriverTests: XCTestCase {
       XCTAssertFalse(linkJob.commandLine.joinedUnresolvedArguments.contains("swiftrt.o"))
     }
 
+    // Embedded WASI link job
+    do {
+      for tripleEnv in ["wasi", "wasi-wasm", "wasip1", "wasip1-wasm", "wasip1-threads"] {
+        var driver = try Driver(
+          args: ["swiftc", "-target", "wasm32-unknown-\(tripleEnv)", "test.o", "-enable-experimental-feature", "Embedded", "-wmo", "-o", "a.wasm"],
+          env: env
+        )
+        let plannedJobs = try driver.planBuild()
+        XCTAssertEqual(plannedJobs.count, 1)
+        let linkJob = plannedJobs[0]
+        XCTAssertFalse(linkJob.commandLine.contains(.flag("-force_load")))
+        XCTAssertFalse(linkJob.commandLine.contains(.flag("-rpath")))
+        XCTAssertFalse(linkJob.commandLine.contains(.flag("-lswiftCore")))
+        XCTAssertFalse(linkJob.commandLine.joinedUnresolvedArguments.contains("swiftrt.o"))
+      }
+    }
+
     do {
       let diags = DiagnosticsEngine()
       var driver = try Driver(args: ["swiftc", "-target", "arm64-apple-macosx10.13",  "test.swift", "-enable-experimental-feature", "Embedded", "-parse-as-library", "-wmo", "-o", "a.out", "-module-name", "main", "-enable-library-evolution"], diagnosticsEngine: diags)
@@ -6874,7 +6891,7 @@ final class SwiftDriverTests: XCTestCase {
       XCTAssertEqual(diags.diagnostics.first!.message.text, Diagnostic.Message.error_need_wmo_embedded.text)
     } catch _ { }
     do {
-      var environment = ProcessEnv.vars
+      var environment = ProcessEnv.block
       environment["SDKROOT"] = nil
 
       // Indexing embedded Swift code should not require WMO