[APIDigester] Build the API digester as a frontend tool instead of a standalone executable

include/swift/APIDigester/ModuleDiagsConsumer.h

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+//===--- ModuleDiagsConsumer.h - Print module differ diagnostics --*- C++ -*-===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+//
+//  This file defines the ModuleDifferDiagsConsumer class, which displays
+//  diagnostics from the module differ as text to an output.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef __SWIFT_MODULE_DIFFER_DIAGS_CONSUMER_H__
+#define __SWIFT_MODULE_DIFFER_DIAGS_CONSUMER_H__
+
+#include "llvm/ADT/MapVector.h"
+#include "swift/Basic/LLVM.h"
+#include "swift/AST/DiagnosticConsumer.h"
+#include "swift/Frontend/PrintingDiagnosticConsumer.h"
+
+#include "llvm/Support/raw_ostream.h"
+#include <set>
+
+namespace swift {
+namespace ide {
+namespace api {
+
+/// Diagnostic consumer that displays diagnostics to standard output.
+class ModuleDifferDiagsConsumer: public PrintingDiagnosticConsumer {
+  llvm::raw_ostream &OS;
+  bool DiagnoseModuleDiff;
+  llvm::MapVector<StringRef, std::set<std::string>> AllDiags;
+public:
+  ModuleDifferDiagsConsumer(bool DiagnoseModuleDiff,
+                            llvm::raw_ostream &OS = llvm::errs());
+  ~ModuleDifferDiagsConsumer();
+  void handleDiagnostic(SourceManager &SM, const DiagnosticInfo &Info) override;
+};
+
+class FilteringDiagnosticConsumer: public DiagnosticConsumer {
+  bool HasError = false;
+  std::unique_ptr<DiagnosticConsumer> subConsumer;
+  std::unique_ptr<llvm::StringSet<>> allowedBreakages;
+  bool shouldProceed(const DiagnosticInfo &Info);
+public:
+  FilteringDiagnosticConsumer(std::unique_ptr<DiagnosticConsumer> subConsumer,
+                              std::unique_ptr<llvm::StringSet<>> allowedBreakages):
+    subConsumer(std::move(subConsumer)),
+    allowedBreakages(std::move(allowedBreakages)) {}
+  ~FilteringDiagnosticConsumer() = default;
+
+  bool finishProcessing() override { return subConsumer->finishProcessing(); }
+  bool hasError() const { return HasError; }
+  void flush() override { subConsumer->flush(); }
+
+  void informDriverOfIncompleteBatchModeCompilation() override {
+    subConsumer->informDriverOfIncompleteBatchModeCompilation();
+  }
+
+  void handleDiagnostic(SourceManager &SM,
+                        const DiagnosticInfo &Info) override;
+};
+}
+}
+}
+
+#endif