Unconditionally build and test MMIOInterposable (#99)

Hopefully improve CI times by building and testing MMIO and
MMIOInterposable in one invocation of swift-test instead of two. This
should avoid invalidating the cache due to manifest changes.

Author: rauhul

Makefile

@@ -49,10 +49,6 @@ test: build
 		--configuration $(CONFIGURATION) \
 		--parallel \
 		--explicit-target-dependency-import-check error
-	@SWIFT_MMIO_FEATURE_INTERPOSABLE=1 swift test \
-		--configuration $(CONFIGURATION) \
-		--parallel \
-		--explicit-target-dependency-import-check error
 
 clean:
 	@echo "cleaning..."

Package.swift

@@ -38,15 +38,26 @@ var package = Package(
       name: "MMIO",
       dependencies: ["MMIOMacros", "MMIOVolatile"]),
     .testTarget(
-      name: "MMIOFileCheckTests",
-      dependencies: ["MMIOUtilities"],
-      exclude: ["Tests"]),
+      name: "MMIOTests",
+      dependencies: ["MMIO", "MMIOUtilities"]),
+
+    // FIXME: feature flag
+    // Ideally this would be represented as MMIO + Feature: Interposable
+    // MMIOInterposable would have a dependency on MMIO with this feature
+    // enabled.
+    .target(
+      name: "MMIOInterposable",
+      dependencies: ["MMIOMacros", "MMIOVolatile"],
+      swiftSettings: [.define("FEATURE_INTERPOSABLE")]),
     .testTarget(
       name: "MMIOInterposableTests",
-      dependencies: ["MMIO", "MMIOUtilities"]),
+      dependencies: ["MMIOInterposable", "MMIOUtilities"],
+      swiftSettings: [.define("FEATURE_INTERPOSABLE")]),
+
     .testTarget(
-      name: "MMIOTests",
-      dependencies: ["MMIO", "MMIOUtilities"]),
+      name: "MMIOFileCheckTests",
+      dependencies: ["MMIOUtilities"],
+      exclude: ["Tests"]),
 
     .macro(
       name: "MMIOMacros",
@@ -128,27 +139,6 @@ var package = Package(
       ]),
   ])
 
-// Replace this with a native SPM feature flag if/when supported.
-let interposable = "FEATURE_INTERPOSABLE"
-if featureIsEnabled(named: interposable, override: nil) {
-  package.products = package.products.filter { $0.name.hasPrefix("MMIO") }
-  let allowedTargets = Set([
-    "MMIO", "MMIOVolatile", "MMIOMacros", "MMIOUtilities",
-    "MMIOInterposableTests",
-  ])
-  package.targets = package.targets.filter {
-    allowedTargets.contains($0.name)
-  }
-  for target in package.targets where target.type != .system {
-    target.swiftDefine(interposable)
-  }
-} else {
-  let disallowedTargets = Set(["MMIOInterposableTests"])
-  package.targets = package.targets.filter {
-    !disallowedTargets.contains($0.name)
-  }
-}
-
 func featureIsEnabled(named featureName: String, override: Bool?) -> Bool {
   let key = "SWIFT_MMIO_\(featureName)"
   let environment = ProcessInfo.processInfo.environment[key] != nil

Sources/MMIOInterposable

@@ -0,0 +1 @@
+MMIO

Tests/MMIOInterposableTests/MMIOInterposableTests.swift

@@ -11,7 +11,7 @@
 
 import XCTest
 
-@testable import MMIO
+@testable import MMIOInterposable
 
 final class MMIOInterposableTests: XCTestCase {
   @RegisterBlock

Tests/MMIOInterposableTests/MMIOTracingInterposer.swift

@@ -9,7 +9,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-import MMIO
+import MMIOInterposable
 import MMIOUtilities
 import XCTest
 

Tests/MMIOInterposableTests/MMIOTracingInterposerEvent.swift

@@ -9,7 +9,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-import MMIO
+import MMIOInterposable
 import MMIOUtilities
 
 struct MMIOTracingInterposerEvent {