Still emit per-task C diagnostics if errors are requested

Sources/SWBBuildSystem/BuildOperation.swift

@@ -1002,6 +1002,10 @@ extension BuildOperation: TaskExecutionDelegate {
     package var emitFrontendCommandLines: Bool {
         buildDescription.emitFrontendCommandLines
     }
+
+    package var continueBuildingAfterErrors: Bool {
+        request.continueBuildingAfterErrors
+    }
 }
 
 // BuildOperation uses reference semantics.

Sources/SWBCore/SpecImplementations/Tools/CCompiler.swift

@@ -1368,7 +1368,8 @@ public class ClangCompilerSpec : CompilerSpec, SpecIdentifierType, GCCCompatible
             extraInputs = []
         }
 
-        if let moduleDependenciesContext {
+        // If validation is set to `YES_ERROR`, individual Clang tasks emit diagnostics, so they need this data in their signature. Otherwise, diagnostics are handled by the per-target validation action so individual compiles are not affected by changes to validation-related build settings.
+        if let moduleDependenciesContext, moduleDependenciesContext.validate == .yesError {
             do {
                 let jsonData = try JSONEncoder(outputFormatting: [.prettyPrinted, .sortedKeys, .withoutEscapingSlashes]).encode(moduleDependenciesContext)
                 guard let signature = String(data: jsonData, encoding: .utf8) else {

Sources/SWBCore/SpecImplementations/Tools/SwiftCompiler.swift

@@ -2405,25 +2405,8 @@ public final class SwiftCompilerSpec : CompilerSpec, SpecIdentifierType, SwiftDi
                     dependencyData = nil
                 }
 
-                let compilationRequirementAdditionalSignatureData: String
-                if let moduleDependenciesContext = cbc.producer.moduleDependenciesContext {
-                    do {
-                        let jsonData = try JSONEncoder(outputFormatting: [.prettyPrinted, .sortedKeys, .withoutEscapingSlashes]).encode(moduleDependenciesContext)
-                        guard let signature = String(data: jsonData, encoding: .utf8) else {
-                            throw StubError.error("non-UTF-8 data")
-                        }
-                        compilationRequirementAdditionalSignatureData = additionalSignatureData + "|\(signature)"
-                    } catch {
-                        delegate.error("failed to serialize 'MODULE_DEPENDENCIES' context information: \(error)")
-                        return
-                    }
-                }
-                else {
-                    compilationRequirementAdditionalSignatureData = additionalSignatureData
-                }
-
                 // Compilation Requirements
-                delegate.createTask(type: self, dependencyData: dependencyData, payload: payload, ruleInfo: ruleInfo("SwiftDriver Compilation Requirements", targetName), additionalSignatureData: compilationRequirementAdditionalSignatureData, commandLine: ["builtin-Swift-Compilation-Requirements", "--"] + args, environment: environmentBindings, workingDirectory: compilerWorkingDirectory(cbc), inputs: allInputsNodes, outputs: compilationRequirementOutputs, action: delegate.taskActionCreationDelegate.createSwiftCompilationRequirementTaskAction(), execDescription: archSpecificExecutionDescription(cbc.scope.namespace.parseString("Unblock downstream dependents of $PRODUCT_NAME"), cbc, delegate), preparesForIndexing: true, enableSandboxing: enableSandboxing, additionalTaskOrderingOptions: [.compilation, .compilationRequirement, .linkingRequirement, .blockedByTargetHeaders, .compilationForIndexableSourceFile], usesExecutionInputs: true, showInLog: true)
+                delegate.createTask(type: self, dependencyData: dependencyData, payload: payload, ruleInfo: ruleInfo("SwiftDriver Compilation Requirements", targetName), additionalSignatureData: additionalSignatureData, commandLine: ["builtin-Swift-Compilation-Requirements", "--"] + args, environment: environmentBindings, workingDirectory: compilerWorkingDirectory(cbc), inputs: allInputsNodes, outputs: compilationRequirementOutputs, action: delegate.taskActionCreationDelegate.createSwiftCompilationRequirementTaskAction(), execDescription: archSpecificExecutionDescription(cbc.scope.namespace.parseString("Unblock downstream dependents of $PRODUCT_NAME"), cbc, delegate), preparesForIndexing: true, enableSandboxing: enableSandboxing, additionalTaskOrderingOptions: [.compilation, .compilationRequirement, .linkingRequirement, .blockedByTargetHeaders, .compilationForIndexableSourceFile], usesExecutionInputs: true, showInLog: true)
 
                 if case .compile = compilationMode {
                     // Unblocking compilation

Sources/SWBCore/SpecImplementations/Tools/ValidateDependencies.swift

@@ -10,6 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+private import Foundation
 public import SWBUtil
 import SWBMacro
 
@@ -39,8 +40,21 @@ public final class ValidateDependenciesSpec: CommandLineToolSpec, SpecImplementa
         guard let configuredTarget = cbc.producer.configuredTarget else {
             return
         }
+
+        let jsonData: Data
+        do {
+            jsonData = try JSONEncoder(outputFormatting: [.prettyPrinted, .sortedKeys, .withoutEscapingSlashes]).encode(payload)
+        } catch {
+            delegate.error("Error serializing \(payload): \(error)")
+            return
+        }
+        guard let signature = String(data: jsonData, encoding: .utf8) else {
+            delegate.error("non-UTF-8 data in signature for ValidateDependencies")
+            return
+        }
+
         let output =  delegate.createVirtualNode("ValidateDependencies \(configuredTarget.guid)")
-        delegate.createTask(type: self, payload: payload, ruleInfo: ["ValidateDependencies"], commandLine: ["builtin-validate-dependencies"] + dependencyInfos.map { $0.path.str }, environment: EnvironmentBindings(), workingDirectory: cbc.producer.defaultWorkingDirectory, inputs: dependencyInfos + cbc.commandOrderingInputs, outputs: [output], action: delegate.taskActionCreationDelegate.createValidateDependenciesTaskAction(), preparesForIndexing: false, enableSandboxing: false)
+        delegate.createTask(type: self, payload: payload, ruleInfo: ["ValidateDependencies"], additionalSignatureData: signature, commandLine: ["builtin-validate-dependencies"] + dependencyInfos.map { $0.path.str }, environment: EnvironmentBindings(), workingDirectory: cbc.producer.defaultWorkingDirectory, inputs: dependencyInfos + cbc.commandOrderingInputs, outputs: [output], action: delegate.taskActionCreationDelegate.createValidateDependenciesTaskAction(), preparesForIndexing: false, enableSandboxing: false)
     }
 }
 

Sources/SWBTaskExecution/Task.swift

@@ -583,6 +583,8 @@ public protocol TaskExecutionDelegate
 
     var namespace: MacroNamespace { get }
 
+    var continueBuildingAfterErrors: Bool { get }
+
     /// Notifies the delegate that this task has discovered a target dependency which must exist to ensure deterministic builds.
     func taskDiscoveredRequiredTargetDependency(target: ConfiguredTarget, antecedent: ConfiguredTarget, reason: RequiredTargetDependencyReason, warningLevel: BooleanWarningLevel)
 }

Sources/SWBTaskExecution/TaskActions/ClangCompileTaskAction.swift

@@ -261,6 +261,20 @@ public final class ClangCompileTaskAction: TaskAction, BuildValueValidatingTaskA
                 moduleDependenciesContext = nil
                 dependencyValidationOutputPath = nil
             }
+
+            // Emit per-task diagnostics if validation is set to `YES_ERROR` and we're not continuing to build after errors.
+            let moduleDependenciesEmitPerTaskDiagnostics = moduleDependenciesContext?.validate == .yesError && !executionDelegate.continueBuildingAfterErrors
+            if moduleDependenciesEmitPerTaskDiagnostics, let dependencyValidationOutputPath {
+                // Since we're emitting per task diagnostics, communicate empty diagnostics to the validation task.
+                let validationInfo = DependencyValidationInfo(payload: .clangDependencies(files: []))
+                _ = try executionDelegate.fs.writeIfChanged(
+                    dependencyValidationOutputPath,
+                    contents: ByteString(
+                        JSONEncoder(outputFormatting: .sortedKeys).encode(validationInfo)
+                    )
+                )
+            }
+
             if let traceFilePath {
                 // Remove the trace output file if it already exists.
                 if executionDelegate.fs.exists(traceFilePath) {
@@ -325,28 +339,41 @@ public final class ClangCompileTaskAction: TaskAction, BuildValueValidatingTaskA
                 }
             }
 
-            if lastResult == .succeeded {
+            if lastResult == .succeeded, let moduleDependenciesContext {
                 // Verify the dependencies from the trace data.
                 let payload: DependencyValidationInfo.Payload
+                var allFiles = Set<Path>()
                 if let traceFilePath {
                     let fs = executionDelegate.fs
                     let traceData = try JSONDecoder().decode(Array<TraceData>.self, from: Data(fs.read(traceFilePath)))
 
-                    var allFiles = Set<Path>()
                     traceData.forEach { allFiles.formUnion(Set($0.includes)) }
                     payload = .clangDependencies(files: allFiles.map { $0.str })
                 } else {
                     payload = .unsupported
                 }
 
-                if let dependencyValidationOutputPath {
-                    let validationInfo = DependencyValidationInfo(payload: payload)
-                    _ = try executionDelegate.fs.writeIfChanged(
-                        dependencyValidationOutputPath,
-                        contents: ByteString(
-                            JSONEncoder(outputFormatting: .sortedKeys).encode(validationInfo)
+                if moduleDependenciesEmitPerTaskDiagnostics {
+                    let missingDeps = moduleDependenciesContext.computeMissingDependencies(files: Array(allFiles))
+                    let diagnostics = moduleDependenciesContext.makeDiagnostics(missingDependencies: missingDeps)
+
+                    for diagnostic in diagnostics {
+                        outputDelegate.emit(diagnostic)
+                    }
+
+                    if diagnostics.contains(where: { $0.behavior == .error }) {
+                        return .failed
+                    }
+                } else {
+                    if let dependencyValidationOutputPath {
+                        let validationInfo = DependencyValidationInfo(payload: payload)
+                        _ = try executionDelegate.fs.writeIfChanged(
+                            dependencyValidationOutputPath,
+                            contents: ByteString(
+                                JSONEncoder(outputFormatting: .sortedKeys).encode(validationInfo)
+                            )
                         )
-                    )
+                    }
                 }
             }
 

Tests/SWBTaskExecutionTests/InProcessTaskTestSupport.swift

@@ -42,6 +42,7 @@ struct MockExecutionDelegate: TaskExecutionDelegate {
     var namespace: MacroNamespace
     var requestContext: SWBCore.BuildRequestContext { fatalError() }
     var emitFrontendCommandLines: Bool { false }
+    var continueBuildingAfterErrors: Bool { false }
     private var core: Core?
 
     func taskDiscoveredRequiredTargetDependency(target: ConfiguredTarget, antecedent: ConfiguredTarget, reason: RequiredTargetDependencyReason, warningLevel: BooleanWarningLevel) {}