From 16176fa854f3df4624fe69a469dd2f9c64482d40 Mon Sep 17 00:00:00 2001
From: Alex Hoppen <ahoppen@apple.com>
Date: Thu, 2 Apr 2026 13:46:33 +0200
Subject: [PATCH 1/2] Start passing `pluginConfiguration` to `BuildDescription`
 initializer in SwiftPMBuildServer
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To stage in https://github.com/swiftlang/swift-package-manager/pull/9583 because SwiftPM doesn’t support cross-PR testing.
---
 Sources/BuildServerIntegration/SwiftPMBuildServer.swift | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/Sources/BuildServerIntegration/SwiftPMBuildServer.swift b/Sources/BuildServerIntegration/SwiftPMBuildServer.swift
index 042cf6177..d888de9d3 100644
--- a/Sources/BuildServerIntegration/SwiftPMBuildServer.swift
+++ b/Sources/BuildServerIntegration/SwiftPMBuildServer.swift
@@ -511,7 +511,7 @@ package actor SwiftPMBuildServer: BuiltInBuildServer {
 
       signposter.emitEvent("Finished generating build plan", id: signpostID)
 
-      buildDescription = BuildDescription(buildPlan: plan)
+      buildDescription = BuildDescription(buildPlan: plan, pluginConfiguration: self.pluginConfiguration)
     }
 
     /// Make sure to execute any throwing statements before setting any
@@ -982,3 +982,10 @@ fileprivate extension SourceKitLSPOptions.BackgroundPreparationMode {
 }
 
 #endif
+
+extension SourceKitLSPAPI.BuildDescription {
+  @_disfavoredOverload
+  init(buildPlan: Build.BuildPlan, pluginConfiguration: PluginConfiguration) {
+    self.init(buildPlan: buildPlan)
+  }
+}

From 1d755bf7733b5bc00c572a25f9cacd1524b0599f Mon Sep 17 00:00:00 2001
From: Alex Hoppen <ahoppen@apple.com>
Date: Sat, 10 Jan 2026 12:26:31 +0100
Subject: [PATCH 2/2] Adopt changed SourceKitLSPAPI to return build settings
 for build plugins

Companion of https://github.com/swiftlang/swift-package-manager/pull/9583.

Fixes #2115
---
 .../SwiftPMBuildServer.swift                  |  7 ---
 .../SwiftPMIntegrationTests.swift             | 52 +++++++++++++++++++
 2 files changed, 52 insertions(+), 7 deletions(-)

diff --git a/Sources/BuildServerIntegration/SwiftPMBuildServer.swift b/Sources/BuildServerIntegration/SwiftPMBuildServer.swift
index d888de9d3..0c8431430 100644
--- a/Sources/BuildServerIntegration/SwiftPMBuildServer.swift
+++ b/Sources/BuildServerIntegration/SwiftPMBuildServer.swift
@@ -982,10 +982,3 @@ fileprivate extension SourceKitLSPOptions.BackgroundPreparationMode {
 }
 
 #endif
-
-extension SourceKitLSPAPI.BuildDescription {
-  @_disfavoredOverload
-  init(buildPlan: Build.BuildPlan, pluginConfiguration: PluginConfiguration) {
-    self.init(buildPlan: buildPlan)
-  }
-}
diff --git a/Tests/SourceKitLSPTests/SwiftPMIntegrationTests.swift b/Tests/SourceKitLSPTests/SwiftPMIntegrationTests.swift
index c04583dac..15ba5f50e 100644
--- a/Tests/SourceKitLSPTests/SwiftPMIntegrationTests.swift
+++ b/Tests/SourceKitLSPTests/SwiftPMIntegrationTests.swift
@@ -902,4 +902,56 @@ final class SwiftPMIntegrationTests: SourceKitLSPTestCase {
     let xSymbol = try XCTUnwrap(fooSymbol.children?.first(where: { $0.name == "x" }))
     XCTAssertEqual(xSymbol.kind, .property)
   }
+
+  func testPackagePlugin() async throws {
+    let project = try await SwiftPMTestProject(
+      files: [
+        "Test.swift": "",
+        "Plugins/PrintMessage/Plugin.swift": """
+        import PackagePlugin
+
+        @main
+        struct PrintMessagePlugin: CommandPlugin {
+          func performCommand(context: PluginContext, arguments: [String]) throws {
+            print("Message")
+            let x: String = 1
+          }
+        }
+        """,
+      ],
+      manifest: """
+        import PackageDescription
+
+        let package = Package(
+          name: "PrintMessage",
+          platforms: [.macOS(.v14)],
+          products: [
+            .plugin(
+              name: "PrintMessage",
+              targets: ["PrintMessage"]
+            )
+          ],
+          targets: [
+            .target(name: "MyLibrary"),
+            .plugin(
+              name: "PrintMessage",
+              capability: .command(
+                intent: .custom(
+                  verb: "print-message",
+                  description: "Prints message"
+                )
+              )
+            )
+          ]
+        )
+        """,
+      // enableBackgroundIndexing: true
+    )
+    let (uri, _) = try! project.openDocument("Plugin.swift")
+    let diags = try await project.testClient.send(DocumentDiagnosticsRequest(textDocument: TextDocumentIdentifier(uri)))
+    XCTAssertEqual(
+      diags.fullReport?.items.map(\.message),
+      ["Cannot convert value of type 'Int' to specified type 'String'"]
+    )
+  }
 }