From c7531694348228207ca17624cb9a8d3e2d54a0ac Mon Sep 17 00:00:00 2001
From: Paul LeMarquand <plemarquand@apple.com>
Date: Wed, 3 Jul 2024 10:06:31 -0400
Subject: [PATCH] Respect module name argument order precedence

When the same flag is specified multiple times the last one found is
used.
---
 Sources/SKCore/BuildSystemManager.swift       |  4 +-
 .../WorkspaceTestDiscoveryTests.swift         | 51 +++++++++++++++++++
 2 files changed, 53 insertions(+), 2 deletions(-)

diff --git a/Sources/SKCore/BuildSystemManager.swift b/Sources/SKCore/BuildSystemManager.swift
index 92a824fad..3e45c7683 100644
--- a/Sources/SKCore/BuildSystemManager.swift
+++ b/Sources/SKCore/BuildSystemManager.swift
@@ -166,14 +166,14 @@ extension BuildSystemManager {
     switch language {
     case .swift:
       // Module name is specified in the form -module-name MyLibrary
-      guard let moduleNameFlagIndex = buildSettings.compilerArguments.firstIndex(of: "-module-name") else {
+      guard let moduleNameFlagIndex = buildSettings.compilerArguments.lastIndex(of: "-module-name") else {
         return nil
       }
       return buildSettings.compilerArguments[safe: moduleNameFlagIndex + 1]
     case .objective_c:
       // Specified in the form -fmodule-name=MyLibrary
       guard
-        let moduleNameArgument = buildSettings.compilerArguments.first(where: {
+        let moduleNameArgument = buildSettings.compilerArguments.last(where: {
           $0.starts(with: "-fmodule-name=")
         }),
         let moduleName = moduleNameArgument.split(separator: "=").last
diff --git a/Tests/SourceKitLSPTests/WorkspaceTestDiscoveryTests.swift b/Tests/SourceKitLSPTests/WorkspaceTestDiscoveryTests.swift
index 3aeebc265..a182ccf83 100644
--- a/Tests/SourceKitLSPTests/WorkspaceTestDiscoveryTests.swift
+++ b/Tests/SourceKitLSPTests/WorkspaceTestDiscoveryTests.swift
@@ -305,6 +305,57 @@ final class WorkspaceTestDiscoveryTests: XCTestCase {
     )
   }
 
+  func testTargetWithCustomModuleName() async throws {
+    let packageManifestWithCustomModuleName = """
+      let package = Package(
+        name: "MyLibrary",
+        targets: [
+          .testTarget(
+            name: "MyLibraryTests",
+            swiftSettings: [
+              .unsafeFlags(["-module-name", "Foo", "-module-name", "Bar"])
+            ]
+          )
+        ]
+      )
+      """
+
+    let project = try await SwiftPMTestProject(
+      files: [
+        "Tests/MyLibraryTests/MyTests.swift": """
+        import XCTest
+
+        1️⃣class MyTests: XCTestCase {
+          2️⃣func testMyLibrary() {}3️⃣
+        }4️⃣
+        """
+      ],
+      manifest: packageManifestWithCustomModuleName
+    )
+
+    // Last argument takes precedence, so expect Bar as the module name.
+
+    let tests = try await project.testClient.send(WorkspaceTestsRequest())
+
+    XCTAssertEqual(
+      tests,
+      [
+        TestItem(
+          id: "Bar.MyTests",
+          label: "MyTests",
+          location: try project.location(from: "1️⃣", to: "4️⃣", in: "MyTests.swift"),
+          children: [
+            TestItem(
+              id: "Bar.MyTests/testMyLibrary()",
+              label: "testMyLibrary()",
+              location: try project.location(from: "2️⃣", to: "3️⃣", in: "MyTests.swift")
+            )
+          ]
+        )
+      ]
+    )
+  }
+
   func testMultipleTargetsWithSameXCTestClassName() async throws {
     let packageManifestWithTwoTestTargets = """
       let package = Package(