Add the ability to control the environment passed to the manifest and…

… plugin compilation

It defaults to `ProcessEnv.vars` so that there is no change in semantics unless the client code customizes the environment.

Sources/PackageLoading/ManifestLoader.swift

@@ -763,7 +763,7 @@ public final class ManifestLoader: ManifestLoaderProtocol {
             cmd += ["-o", compiledManifestFile.pathString]
 
             // Compile the manifest.
-            let compilerResult = try Process.popen(arguments: cmd)
+            let compilerResult = try Process.popen(arguments: cmd, environment: toolchain.swiftCompilerEnvironment)
             let compilerOutput = try (compilerResult.utf8Output() + compilerResult.utf8stderrOutput()).spm_chuzzle()
             result.compilerOutput = compilerOutput
 

Sources/PackageModel/ToolchainConfiguration.swift

@@ -21,6 +21,9 @@ public struct ToolchainConfiguration {
     /// Extra arguments to pass the Swift compiler (defaults to the empty string).
     public var swiftCompilerFlags: [String]
 
+    /// Environment to pass to the Swift compiler (defaults to the inherited environment).
+    public var swiftCompilerEnvironment: [String: String]
+
     /// The path of the library resources.
     public var libDir: AbsolutePath
 
@@ -47,13 +50,15 @@ public struct ToolchainConfiguration {
     public init(
         swiftCompiler: AbsolutePath,
         swiftCompilerFlags: [String] = [],
+        swiftCompilerEnvironment: [String: String] = ProcessEnv.vars,
         libDir: AbsolutePath? = nil,
         binDir: AbsolutePath? = nil,
         sdkRoot: AbsolutePath? = nil,
         xctestLocation: AbsolutePath? = nil
     ) {
         self.swiftCompiler = swiftCompiler
         self.swiftCompilerFlags = swiftCompilerFlags
+        self.swiftCompilerEnvironment = swiftCompilerEnvironment
         self.libDir = libDir ?? Self.libDir(forBinDir: swiftCompiler.parentDirectory)
         self.binDir = binDir
         self.sdkRoot = sdkRoot

Sources/Workspace/DefaultPluginScriptRunner.swift

@@ -114,7 +114,7 @@ public struct DefaultPluginScriptRunner: PluginScriptRunner {
         let compiledExec = cacheDir.appending(component: "compiled-plugin")
         command += ["-o", compiledExec.pathString]
 
-        let result = try Process.popen(arguments: command)
+        let result = try Process.popen(arguments: command, environment: toolchain.swiftCompilerEnvironment)
         let output = try (result.utf8Output() + result.utf8stderrOutput()).spm_chuzzle() ?? ""
         if result.exitStatus != .terminated(code: 0) {
             // TODO: Make this a proper error.

Tests/PackageLoadingTests/PD_5_0_LoadingTests.swift

@@ -547,4 +547,53 @@ class PackageDescription5_0LoadingTests: PackageDescriptionLoadingTests {
             XCTAssertEqual(manifest.dependencies, [])
         }
     }
+
+    func testManifestLoaderEnvironment() throws {
+        try testWithTemporaryDirectory { path in
+            let fs = localFileSystem
+
+            let packagePath = path.appending(component: "pkg")
+            let manifestPath = packagePath.appending(component: "Package.swift")
+            try fs.writeFileContents(manifestPath) { stream in
+                stream <<< """
+                // swift-tools-version:5
+                import PackageDescription
+
+                let package = Package(
+                    name: "Trivial",
+                    targets: [
+                        .target(
+                            name: "foo",
+                            dependencies: []),
+                    ]
+                )
+                """
+            }
+
+            let moduleTraceFilePath = path.appending(component: "swift-module-trace")
+            var toolchain = ToolchainConfiguration.default
+            toolchain.swiftCompilerEnvironment["SWIFT_LOADED_MODULE_TRACE_FILE"] = moduleTraceFilePath.pathString
+            let manifestLoader = ManifestLoader(
+                toolchain: toolchain,
+                serializedDiagnostics: true,
+                isManifestSandboxEnabled: false,
+                cacheDir: nil)
+
+            let diagnostics = DiagnosticsEngine()
+            let manifest = try manifestLoader.load(
+                at: manifestPath.parentDirectory,
+                packageKind: .local,
+                packageLocation: manifestPath.pathString,
+                toolsVersion: .v5,
+                fileSystem: fs,
+                diagnostics: diagnostics
+            )
+
+            XCTAssertTrue(diagnostics.diagnostics.isEmpty)
+            XCTAssertEqual(manifest.name, "Trivial")
+
+            let moduleTraceJSON = try XCTUnwrap(try localFileSystem.readFileContents(moduleTraceFilePath).validDescription)
+            XCTAssert(moduleTraceJSON.contains("PackageDescription"))
+        }
+    }
 }