From 36cda8e4dc6e5a152fb3f7300d334fa191832775 Mon Sep 17 00:00:00 2001
From: Owen Voorhees <ovoorhees@apple.com>
Date: Mon, 8 Dec 2025 14:23:28 -0800
Subject: [PATCH] Use the correct module name for executable targets combined
 with an executable product with a different name

---
 .../Package.swift                             | 20 +++++++++++++++
 .../Sources/TestableExe/main.swift            |  5 ++++
 .../TestableExeTests/TestableExeTests.swift   |  8 ++++++
 .../PackagePIFProjectBuilder+Products.swift   |  5 ++--
 Tests/CommandsTests/TestCommandTests.swift    | 25 +++++++++++++++++++
 5 files changed, 61 insertions(+), 2 deletions(-)
 create mode 100644 Fixtures/Miscellaneous/TestableExeWithDifferentProductName/Package.swift
 create mode 100644 Fixtures/Miscellaneous/TestableExeWithDifferentProductName/Sources/TestableExe/main.swift
 create mode 100644 Fixtures/Miscellaneous/TestableExeWithDifferentProductName/Tests/TestableExeTests/TestableExeTests.swift

diff --git a/Fixtures/Miscellaneous/TestableExeWithDifferentProductName/Package.swift b/Fixtures/Miscellaneous/TestableExeWithDifferentProductName/Package.swift
new file mode 100644
index 00000000000..5a2c88b9cef
--- /dev/null
+++ b/Fixtures/Miscellaneous/TestableExeWithDifferentProductName/Package.swift
@@ -0,0 +1,20 @@
+// swift-tools-version: 5.5
+import PackageDescription
+
+let package = Package(
+    name: "TestableExe",
+    products: [
+        .executable(name: "testable-exe", targets: ["TestableExe"])
+    ],
+    targets: [
+        .executableTarget(
+            name: "TestableExe"
+        ),
+        .testTarget(
+            name: "TestableExeTests",
+            dependencies: [
+                "TestableExe",
+            ]
+        ),
+    ]
+)
diff --git a/Fixtures/Miscellaneous/TestableExeWithDifferentProductName/Sources/TestableExe/main.swift b/Fixtures/Miscellaneous/TestableExeWithDifferentProductName/Sources/TestableExe/main.swift
new file mode 100644
index 00000000000..c10c21ba070
--- /dev/null
+++ b/Fixtures/Miscellaneous/TestableExeWithDifferentProductName/Sources/TestableExe/main.swift
@@ -0,0 +1,5 @@
+public func functionFromTestableExecutable() {
+    print("Hello, world")
+}
+
+functionFromTestableExecutable()
diff --git a/Fixtures/Miscellaneous/TestableExeWithDifferentProductName/Tests/TestableExeTests/TestableExeTests.swift b/Fixtures/Miscellaneous/TestableExeWithDifferentProductName/Tests/TestableExeTests/TestableExeTests.swift
new file mode 100644
index 00000000000..3dcde32af9b
--- /dev/null
+++ b/Fixtures/Miscellaneous/TestableExeWithDifferentProductName/Tests/TestableExeTests/TestableExeTests.swift
@@ -0,0 +1,8 @@
+import XCTest
+@testable import TestableExe
+
+final class TestableExeTests: XCTestCase {
+    func testExample() throws {
+        functionFromTestableExecutable()
+    }
+}
diff --git a/Sources/SwiftBuildSupport/PackagePIFProjectBuilder+Products.swift b/Sources/SwiftBuildSupport/PackagePIFProjectBuilder+Products.swift
index e7c75b928d6..cb9978fd5ba 100644
--- a/Sources/SwiftBuildSupport/PackagePIFProjectBuilder+Products.swift
+++ b/Sources/SwiftBuildSupport/PackagePIFProjectBuilder+Products.swift
@@ -112,7 +112,8 @@ extension PackagePIFProjectBuilder {
         settings[.TARGET_NAME] = product.name
         settings[.PACKAGE_RESOURCE_TARGET_KIND] = "regular"
         settings[.PRODUCT_NAME] = "$(TARGET_NAME)"
-        settings[.PRODUCT_MODULE_NAME] = product.c99name
+        // We must use the main module name here instead of the product name, because they're not guranteed to be the same, and the users may have authored e.g. tests which rely on an executable's module name.
+        settings[.PRODUCT_MODULE_NAME] = mainModule.c99name
         settings[.PRODUCT_BUNDLE_IDENTIFIER] = "\(self.package.identity).\(product.name)"
             .spm_mangledToBundleIdentifier()
         settings[.SWIFT_PACKAGE_NAME] = mainModule.packageName
@@ -415,7 +416,7 @@ extension PackagePIFProjectBuilder {
                 case .executable, .snippet:
                     // For executable targets, we depend on the *product* instead
                     // (i.e., we infuse the product's main module target into the one for the product itself).
-                    let productDependency = modulesGraph.allProducts.only { $0.name == moduleDependency.name }
+                    let productDependency = modulesGraph.allProducts.only { $0.mainModule?.name == moduleDependency.name }
                     if let productDependency {
                         let productDependencyGUID = productDependency.pifTargetGUID
                         self.project[keyPath: mainModuleTargetKeyPath].common.addDependency(
diff --git a/Tests/CommandsTests/TestCommandTests.swift b/Tests/CommandsTests/TestCommandTests.swift
index 38961e48428..fc73f713412 100644
--- a/Tests/CommandsTests/TestCommandTests.swift
+++ b/Tests/CommandsTests/TestCommandTests.swift
@@ -317,6 +317,31 @@ struct TestCommandTests {
         }
     }
 
+    @Test(
+        .IssueWindowsLongPath,
+        .tags(
+            .Feature.TargetType.Executable,
+        ),
+        arguments: SupportedBuildSystemOnAllPlatforms, BuildConfiguration.allCases,
+    )
+    func testableExecutableWithDifferentlyNamedExecutableProduct(
+        buildSystem: BuildSystemProvider.Kind,
+        configuration: BuildConfiguration,
+    ) async throws {
+        try await withKnownIssue(isIntermittent: true) {
+            try await fixture(name: "Miscellaneous/TestableExeWithDifferentProductName") { fixturePath in
+                let result = try await execute(
+                    ["--vv"],
+                    packagePath: fixturePath,
+                    configuration: configuration,
+                    buildSystem: buildSystem,
+                )
+            }
+        } when: {
+            .windows == ProcessInfo.hostOperatingSystem
+        }
+    }
+
     @Test(
         .tags(
             .Feature.TargetType.Executable,