Create dylibs by default when using XCBuild (apple#2860)

This changes the default to be dylibs when using XCBuild since we only
create frameworks in Xcode for App Store submission. It also fixes an
issue where even when dylib creation was enabled, we weren't producing
dylibs.

rdar://problem/66849186

Sources/SPMBuildCore/BuildParameters.swift

@@ -141,7 +141,7 @@ public struct BuildParameters: Encodable {
         jobs: UInt32 = UInt32(ProcessInfo.processInfo.activeProcessorCount),
         shouldLinkStaticSwiftStdlib: Bool = false,
         shouldEnableManifestCaching: Bool = false,
-        shouldCreateDylibForDynamicProducts: Bool = false,
+        shouldCreateDylibForDynamicProducts: Bool = true,
         sanitizers: EnabledSanitizers = EnabledSanitizers(),
         enableCodeCoverage: Bool = false,
         indexStoreMode: IndexStoreMode = .auto,

Sources/XCBuildSupport/PIFBuilder.swift

@@ -450,9 +450,15 @@ final class PackagePIFProjectBuilder: PIFProjectBuilder {
         let executableName: String
         let productType: PIF.Target.ProductType
         if product.type == .library(.dynamic) {
-            pifTargetProductName = product.name + ".framework"
-            executableName = product.name
-            productType = .framework
+            if parameters.shouldCreateDylibForDynamicProducts {
+                pifTargetProductName = "lib\(product.name).dylib"
+                executableName = pifTargetProductName
+                productType = .dynamicLibrary
+            } else {
+                pifTargetProductName = product.name + ".framework"
+                executableName = product.name
+                productType = .framework
+            }
         } else {
             pifTargetProductName = "lib\(product.name).a"
             executableName = pifTargetProductName

Tests/XCBuildSupportTests/PIFBuilderTests.swift

@@ -1397,6 +1397,52 @@ class PIFBuilderTests: XCTestCase {
         }
     }
 
+    func testLibraryTargetsAsDylib() {
+        let fs = InMemoryFileSystem(emptyFiles:
+            "/Bar/Sources/BarLib/lib.c"
+        )
+
+        let diagnostics = DiagnosticsEngine()
+        let graph = loadPackageGraph(
+            fs: fs,
+            diagnostics: diagnostics,
+            manifests: [
+                Manifest.createManifest(
+                    name: "Bar",
+                    path: "/Bar",
+                    url: "/Bar",
+                    v: .v4_2,
+                    packageKind: .root,
+                    cLanguageStandard: "c11",
+                    swiftLanguageVersions: [.v4_2],
+                    products: [
+                        .init(name: "BarLib", type: .library(.dynamic), targets: ["BarLib"]),
+                    ],
+                    targets: [
+                        .init(name: "BarLib"),
+                    ]),
+            ]
+        )
+
+        var pif: PIF.TopLevelObject!
+        try! withCustomEnv(["PKG_CONFIG_PATH": inputsDir.pathString]) {
+            let builder = PIFBuilder(graph: graph, parameters: .mock(shouldCreateDylibForDynamicProducts: true), diagnostics: diagnostics)
+            pif = builder.construct()
+        }
+
+        XCTAssertNoDiagnostics(diagnostics)
+
+        PIFTester(pif) { workspace in
+            workspace.checkProject("PACKAGE:/Bar") { project in
+                project.checkTarget("PACKAGE-PRODUCT:BarLib") { target in
+                    XCTAssertEqual(target.name, "BarLib")
+                    XCTAssertEqual(target.productType, .dynamicLibrary)
+                    XCTAssertEqual(target.productName, "libBarLib.dylib")
+                }
+            }
+        }
+    }
+
     func testSystemLibraryTargets() {
         let fs = InMemoryFileSystem(emptyFiles:
             "/Foo/Sources/SystemLib1/module.modulemap",