1 files changed, 138 insertions, 0 deletions
diff --git a/clang/lib/AST/ExternalASTSource.cpp b/clang/lib/AST/ExternalASTSource.cpp
new file mode 100644
index 000000000000..730102757440
--- /dev/null
+++ b/clang/lib/AST/ExternalASTSource.cpp
@@ -0,0 +1,138 @@
+//===- ExternalASTSource.cpp - Abstract External AST Interface ------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+//  This file provides the default implementation of the ExternalASTSource
+//  interface, which enables construction of AST nodes from some external
+//  source.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/AST/ExternalASTSource.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/DeclarationName.h"
+#include "clang/Basic/IdentifierTable.h"
+#include "clang/Basic/LLVM.h"
+#include "clang/Basic/Module.h"
+#include "llvm/ADT/None.h"
+#include "llvm/Support/ErrorHandling.h"
+#include <cstdint>
+
+using namespace clang;
+
+ExternalASTSource::~ExternalASTSource() = default;
+
+llvm::Optional<ExternalASTSource::ASTSourceDescriptor>
+ExternalASTSource::getSourceDescriptor(unsigned ID) {
+  return None;
+}
+
+ExternalASTSource::ExtKind
+ExternalASTSource::hasExternalDefinitions(const Decl *D) {
+  return EK_ReplyHazy;
+}
+
+ExternalASTSource::ASTSourceDescriptor::ASTSourceDescriptor(const Module &M)
+  : Signature(M.Signature), ClangModule(&M) {
+  if (M.Directory)
+    Path = M.Directory->getName();
+  if (auto *File = M.getASTFile())
+    ASTFile = File->getName();
+}
+
+std::string ExternalASTSource::ASTSourceDescriptor::getModuleName() const {
+  if (ClangModule)
+    return ClangModule->Name;
+  else
+    return PCHModuleName;
+}
+
+void ExternalASTSource::FindFileRegionDecls(FileID File, unsigned Offset,
+                                            unsigned Length,
+                                            SmallVectorImpl<Decl *> &Decls) {}
+
+void ExternalASTSource::CompleteRedeclChain(const Decl *D) {}
+
+void ExternalASTSource::CompleteType(TagDecl *Tag) {}
+
+void ExternalASTSource::CompleteType(ObjCInterfaceDecl *Class) {}
+
+void ExternalASTSource::ReadComments() {}
+
+void ExternalASTSource::StartedDeserializing() {}
+
+void ExternalASTSource::FinishedDeserializing() {}
+
+void ExternalASTSource::StartTranslationUnit(ASTConsumer *Consumer) {}
+
+void ExternalASTSource::PrintStats() {}
+
+bool ExternalASTSource::layoutRecordType(
+    const RecordDecl *Record, uint64_t &Size, uint64_t &Alignment,
+    llvm::DenseMap<const FieldDecl *, uint64_t> &FieldOffsets,
+    llvm::DenseMap<const CXXRecordDecl *, CharUnits> &BaseOffsets,
+    llvm::DenseMap<const CXXRecordDecl *, CharUnits> &VirtualBaseOffsets) {
+  return false;
+}
+
+Decl *ExternalASTSource::GetExternalDecl(uint32_t ID) {
+  return nullptr;
+}
+
+Selector ExternalASTSource::GetExternalSelector(uint32_t ID) {
+  return Selector();
+}
+
+uint32_t ExternalASTSource::GetNumExternalSelectors() {
+   return 0;
+}
+
+Stmt *ExternalASTSource::GetExternalDeclStmt(uint64_t Offset) {
+  return nullptr;
+}
+
+CXXCtorInitializer **
+ExternalASTSource::GetExternalCXXCtorInitializers(uint64_t Offset) {
+  return nullptr;
+}
+
+CXXBaseSpecifier *
+ExternalASTSource::GetExternalCXXBaseSpecifiers(uint64_t Offset) {
+  return nullptr;
+}
+
+bool
+ExternalASTSource::FindExternalVisibleDeclsByName(const DeclContext *DC,
+                                                  DeclarationName Name) {
+  return false;
+}
+
+void ExternalASTSource::completeVisibleDeclsMap(const DeclContext *DC) {}
+
+void ExternalASTSource::FindExternalLexicalDecls(
+    const DeclContext *DC, llvm::function_ref<bool(Decl::Kind)> IsKindWeWant,
+    SmallVectorImpl<Decl *> &Result) {}
+
+void ExternalASTSource::getMemoryBufferSizes(MemoryBufferSizes &sizes) const {}
+
+uint32_t ExternalASTSource::incrementGeneration(ASTContext &C) {
+  uint32_t OldGeneration = CurrentGeneration;
+
+  // Make sure the generation of the topmost external source for the context is
+  // incremented. That might not be us.
+  auto *P = C.getExternalSource();
+  if (P && P != this)
+    CurrentGeneration = P->incrementGeneration(C);
+  else {
+    // FIXME: Only bump the generation counter if the current generation number
+    // has been observed?
+    if (!++CurrentGeneration)
+      llvm::report_fatal_error("generation counter overflowed", false);
+  }
+
+  return OldGeneration;
+}