Add SwiftBuild coverage support

Ensure the SwiftBuild build systam has feature parity with the Native
build system as it relates to coverage.

Fixes: #9077
Issue: rdar://159461439

Author: bkhouri

Sources/Commands/SwiftTestCommand.swift

@@ -619,7 +619,6 @@ public struct SwiftTestCommand: AsyncSwiftCommand {
             }
         }
         args += ["-o", productsBuildParameters.codeCovDataFile.pathString]
-
         try await AsyncProcess.checkNonZeroExit(arguments: args)
     }
 
@@ -659,7 +658,7 @@ public struct SwiftTestCommand: AsyncSwiftCommand {
             productsBuildParameters: productsBuildParameters,
             toolsBuildParameters: toolsBuildParameters,
             testProduct: self.options.sharedOptions.testProduct,
-            traitConfiguration: .init(traitOptions: self.globalOptions.traits)
+            traitConfiguration: .init(traitOptions: self.globalOptions.traits),
         )
     }
 
@@ -847,7 +846,7 @@ extension SwiftTestCommand {
                 productsBuildParameters: productsBuildParameters,
                 toolsBuildParameters: toolsBuildParameters,
                 testProduct: self.sharedOptions.testProduct,
-                traitConfiguration: .init(traitOptions: self.globalOptions.traits)
+                traitConfiguration: .init(traitOptions: self.globalOptions.traits),
             )
         }
     }
@@ -1555,7 +1554,7 @@ private func buildTestsIfNeeded(
     productsBuildParameters: BuildParameters,
     toolsBuildParameters: BuildParameters,
     testProduct: String?,
-    traitConfiguration: TraitConfiguration
+    traitConfiguration: TraitConfiguration,
 ) async throws -> [BuiltTestProduct] {
     let buildSystem = try await swiftCommandState.createBuildSystem(
         productsBuildParameters: productsBuildParameters,
@@ -1567,7 +1566,6 @@ private func buildTestsIfNeeded(
     } else {
         .allIncludingTests
     }
-
     try await buildSystem.build(subset: subset, buildOutputs: [])
 
     // Find the test product.

Sources/SPMBuildCore/BuildSystem/BuildSystem.swift

@@ -40,7 +40,7 @@ public enum BuildSubset {
 /// result for indication that the output was produced.
 public enum BuildOutput: Equatable {
     public static func == (lhs: BuildOutput, rhs: BuildOutput) -> Bool {
-        switch lhs {    
+        switch lhs {
         case .symbolGraph(let leftOptions):
             switch rhs {
                 case .symbolGraph(let rightOptions):

Sources/SwiftBuildSupport/SwiftBuildSystem.swift

@@ -371,7 +371,7 @@ public final class SwiftBuildSystem: SPMBuildCore.BuildSystem {
     private func startSWBuildOperation(
         pifTargetName: String,
         symbolGraphOptions: BuildOutput.SymbolGraphOptions?,
-        generateReplArguments: Bool
+        generateReplArguments: Bool,
     ) async throws -> BuildResult {
         let buildStartTime = ContinuousClock.Instant.now
         var replArguments: CLIArguments?
@@ -423,7 +423,12 @@ public final class SwiftBuildSystem: SPMBuildCore.BuildSystem {
                         throw error
                     }
 
-                    let request = try await self.makeBuildRequest(session: session, configuredTargets: configuredTargets, derivedDataPath: derivedDataPath, symbolGraphOptions: symbolGraphOptions)
+                    let request = try await self.makeBuildRequest(
+                        session: session,
+                        configuredTargets: configuredTargets,
+                        derivedDataPath: derivedDataPath,
+                        symbolGraphOptions: symbolGraphOptions,
+                    )
 
                     struct BuildState {
                         private var targetsByID: [Int: SwiftBuild.SwiftBuildMessage.TargetStartedInfo] = [:]
@@ -641,7 +646,10 @@ public final class SwiftBuildSystem: SPMBuildCore.BuildSystem {
         )
     }
 
-    private func makeBuildParameters(session: SWBBuildServiceSession, symbolGraphOptions: BuildOutput.SymbolGraphOptions?) async throws -> SwiftBuild.SWBBuildParameters {
+    private func makeBuildParameters(
+        session: SWBBuildServiceSession,
+        symbolGraphOptions: BuildOutput.SymbolGraphOptions?,
+    ) async throws -> SwiftBuild.SWBBuildParameters {
         // Generate the run destination parameters.
         let runDestination = makeRunDestination()
 
@@ -784,9 +792,17 @@ public final class SwiftBuildSystem: SPMBuildCore.BuildSystem {
         return params
     }
 
-    public func makeBuildRequest(session: SWBBuildServiceSession, configuredTargets: [SWBTargetGUID], derivedDataPath: Basics.AbsolutePath, symbolGraphOptions: BuildOutput.SymbolGraphOptions?) async throws -> SWBBuildRequest {
+    public func makeBuildRequest(
+        session: SWBBuildServiceSession,
+        configuredTargets: [SWBTargetGUID],
+        derivedDataPath: Basics.AbsolutePath,
+        symbolGraphOptions: BuildOutput.SymbolGraphOptions?,
+    ) async throws -> SWBBuildRequest {
         var request = SWBBuildRequest()
-        request.parameters = try await makeBuildParameters(session: session, symbolGraphOptions: symbolGraphOptions)
+        request.parameters = try await makeBuildParameters(
+            session: session,
+            symbolGraphOptions: symbolGraphOptions,
+        )
         request.configuredTargets = configuredTargets.map { SWBConfiguredTarget(guid: $0.rawValue, parameters: request.parameters) }
         request.useParallelTargets = true
         request.useImplicitDependencies = false
@@ -879,8 +895,8 @@ public final class SwiftBuildSystem: SPMBuildCore.BuildSystem {
 
     private static func constructTestingSettingsOverrides(from parameters: BuildParameters.Testing) -> [String: String] {
         var settings: [String: String] = [:]
-        // TODO: enableCodeCoverage
-        // explicitlyEnabledTestability
+
+        settings["CLANG_COVERAGE_MAPPING"] = parameters.enableCodeCoverage ? "YES" : "NO"
 
         switch parameters.explicitlyEnabledTestability {
         case true: