3 files changed, 104 insertions, 0 deletions

diff --git a/lib/Frontend/ASTMerge.cpp b/lib/Frontend/ASTMerge.cpp
new file mode 100644
index 0000000000..649af9e4b8
--- /dev/null
+++ b/lib/Frontend/ASTMerge.cpp
@@ -0,0 +1,98 @@
+//===-- ASTMerge.cpp - AST Merging Frontent Action --------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+#include "clang/Frontend/ASTUnit.h"
+#include "clang/Frontend/CompilerInstance.h"
+#include "clang/Frontend/FrontendActions.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/ASTImporter.h"
+
+using namespace clang;
+
+ASTConsumer *ASTMergeAction::CreateASTConsumer(CompilerInstance &CI,
+                                               llvm::StringRef InFile) {
+  return AdaptedAction->CreateASTConsumer(CI, InFile);
+}
+
+bool ASTMergeAction::BeginSourceFileAction(CompilerInstance &CI,
+                                           llvm::StringRef Filename) {
+  // FIXME: This is a hack. We need a better way to communicate the
+  // AST file, compiler instance, and file name than member variables
+  // of FrontendAction.
+  AdaptedAction->setCurrentFile(getCurrentFile(), takeCurrentASTUnit());
+  AdaptedAction->setCompilerInstance(&CI);
+  return AdaptedAction->BeginSourceFileAction(CI, Filename);
+}
+
+void ASTMergeAction::ExecuteAction() {
+  CompilerInstance &CI = getCompilerInstance();
+
+  for (unsigned I = 0, N = ASTFiles.size(); I != N; ++I) {
+    ASTUnit *Unit = ASTUnit::LoadFromPCHFile(ASTFiles[I], CI.getDiagnostics(),
+                                             false, true);
+    if (!Unit)
+      continue;
+
+    ASTImporter Importer(CI.getASTContext(), CI.getDiagnostics(),
+                         Unit->getASTContext(), CI.getDiagnostics());
+
+    TranslationUnitDecl *TU = Unit->getASTContext().getTranslationUnitDecl();
+    for (DeclContext::decl_iterator D = TU->decls_begin(), 
+                                 DEnd = TU->decls_end();
+         D != DEnd; ++D) {
+      // FIXME: We only merge variables whose names start with x. Why
+      // would anyone want anything else?
+      if (VarDecl *VD = dyn_cast<VarDecl>(*D))
+        if (VD->getIdentifier() && 
+            *VD->getIdentifier()->getNameStart() == 'x') {
+          Decl *Merged = Importer.Import(VD);
+          if (Merged)
+            Merged->dump();
+        }
+    }
+
+    delete Unit;
+  }
+
+
+  return AdaptedAction->ExecuteAction();
+}
+
+void ASTMergeAction::EndSourceFileAction() {
+  return AdaptedAction->EndSourceFileAction();
+}
+
+ASTMergeAction::ASTMergeAction(FrontendAction *AdaptedAction,
+                               std::string *ASTFiles, unsigned NumASTFiles)
+  : AdaptedAction(AdaptedAction), ASTFiles(ASTFiles, ASTFiles + NumASTFiles) {
+  assert(AdaptedAction && "ASTMergeAction needs an action to adapt");
+}
+
+ASTMergeAction::~ASTMergeAction() { 
+  delete AdaptedAction;
+}
+
+bool ASTMergeAction::usesPreprocessorOnly() const {
+  return AdaptedAction->usesPreprocessorOnly();
+}
+
+bool ASTMergeAction::usesCompleteTranslationUnit() {
+  return AdaptedAction->usesCompleteTranslationUnit();
+}
+
+bool ASTMergeAction::hasPCHSupport() const {
+  return AdaptedAction->hasPCHSupport();
+}
+
+bool ASTMergeAction::hasASTSupport() const {
+  return AdaptedAction->hasASTSupport();
+}
+
+bool ASTMergeAction::hasCodeCompletionSupport() const {
+  return AdaptedAction->hasCodeCompletionSupport();
+}
diff --git a/lib/Frontend/CMakeLists.txt b/lib/Frontend/CMakeLists.txt
index 58aaa43aab..1d0b5c1204 100644
--- a/lib/Frontend/CMakeLists.txt
+++ b/lib/Frontend/CMakeLists.txt
@@ -2,6 +2,7 @@ set(LLVM_NO_RTTI 1)
 
 add_clang_library(clangFrontend
   ASTConsumers.cpp
+  ASTMerge.cpp
   ASTUnit.cpp
   AnalysisConsumer.cpp
   Backend.cpp
diff --git a/lib/Frontend/CompilerInvocation.cpp b/lib/Frontend/CompilerInvocation.cpp
index 5b64c7e639..006f3c095c 100644
--- a/lib/Frontend/CompilerInvocation.cpp
+++ b/lib/Frontend/CompilerInvocation.cpp
@@ -367,6 +367,10 @@ static void FrontendOptsToArgs(const FrontendOptions &Opts,
     Res.push_back("-load");
     Res.push_back(Opts.Plugins[i]);
   }
+  for (unsigned i = 0, e = Opts.ASTMergeFiles.size(); i != e; ++i) {
+    Res.push_back("-ast-merge");
+    Res.push_back(Opts.ASTMergeFiles[i]);
+  }
 }
 
 static void HeaderSearchOptsToArgs(const HeaderSearchOptions &Opts,
@@ -929,6 +933,7 @@ ParseFrontendArgs(FrontendOptions &Opts, ArgList &Args, Diagnostic &Diags) {
   Opts.ShowTimers = Args.hasArg(OPT_ftime_report);
   Opts.ShowVersion = Args.hasArg(OPT_version);
   Opts.ViewClassInheritance = getLastArgValue(Args, OPT_cxx_inheritance_view);
+  Opts.ASTMergeFiles = getAllArgValues(Args, OPT_ast_merge);
 
   FrontendOptions::InputKind DashX = FrontendOptions::IK_None;
   if (const Arg *A = Args.getLastArg(OPT_x)) {