[ASTImporter] Mark erroneous nodes in shared st

Summary:
Now we store the errors for the Decls in the "to" context too. For
that, however, we have to put these errors in a shared state (among all
the ASTImporter objects which handle the same "to" context but different
"from" contexts).

After a series of imports from different "from" TUs we have a "to" context
which may have erroneous nodes in it. (Remember, the AST is immutable so
there is no way to delete a node once we had created it and we realized
the error later.) All these erroneous nodes are marked in
ASTImporterSharedState::ImportErrors.  Clients of the ASTImporter may
use this as an input. E.g. the static analyzer engine may not try to
analyze a function if that is marked as erroneous (it can be queried via
ASTImporterSharedState::getImportDeclErrorIfAny()).

Reviewers: a_sidorin, a.sidorin, shafik

Subscribers: rnkovacs, dkrupp, Szelethus, gamesh411, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D62376

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@364785 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 83 insertions, 9 deletions

diff --git a/include/clang/AST/ASTImporter.h b/include/clang/AST/ASTImporter.h
index e0089bb702..21b1bbbfd7 100644
--- a/include/clang/AST/ASTImporter.h
+++ b/include/clang/AST/ASTImporter.h
@@ -32,8 +32,8 @@
 namespace clang {
 
 class ASTContext;
+class ASTImporterSharedState;
 class Attr;
-class ASTImporterLookupTable;
 class CXXBaseSpecifier;
 class CXXCtorInitializer;
 class Decl;
@@ -209,13 +209,7 @@ class TypeSourceInfo;
     };
 
   private:
-
-    /// Pointer to the import specific lookup table, which may be shared
-    /// amongst several ASTImporter objects.
-    /// This is an externally managed resource (and should exist during the
-    /// lifetime of the ASTImporter object)
-    /// If not set then the original C/C++ lookup is used.
-    ASTImporterLookupTable *LookupTable = nullptr;
+    std::shared_ptr<ASTImporterSharedState> SharedState = nullptr;
 
     /// The path which we go through during the import of a given AST node.
     ImportPathTy ImportPath;
@@ -311,7 +305,7 @@ class TypeSourceInfo;
     ASTImporter(ASTContext &ToContext, FileManager &ToFileManager,
                 ASTContext &FromContext, FileManager &FromFileManager,
                 bool MinimalImport,
-                ASTImporterLookupTable *LookupTable = nullptr);
+                std::shared_ptr<ASTImporterSharedState> SharedState = nullptr);
 
     virtual ~ASTImporter();
 
diff --git a/include/clang/AST/ASTImporterSharedState.h b/include/clang/AST/ASTImporterSharedState.h
new file mode 100644
index 0000000000..e384950590
--- /dev/null
+++ b/include/clang/AST/ASTImporterSharedState.h
@@ -0,0 +1,80 @@
+//===- ASTImporterSharedState.h - ASTImporter specific state --*- C++ -*---===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//  This file defines the ASTImporter specific state, which may be shared
+//  amongst several ASTImporter objects.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_AST_ASTIMPORTERSHAREDSTATE_H
+#define LLVM_CLANG_AST_ASTIMPORTERSHAREDSTATE_H
+
+#include "clang/AST/ASTImporterLookupTable.h"
+#include "llvm/ADT/DenseMap.h"
+// FIXME We need this because of ImportError.
+#include "clang/AST/ASTImporter.h"
+
+namespace clang {
+
+class TranslationUnitDecl;
+
+/// Importer specific state, which may be shared amongst several ASTImporter
+/// objects.
+class ASTImporterSharedState {
+
+  /// Pointer to the import specific lookup table.
+  std::unique_ptr<ASTImporterLookupTable> LookupTable;
+
+  /// Mapping from the already-imported declarations in the "to"
+  /// context to the error status of the import of that declaration.
+  /// This map contains only the declarations that were not correctly
+  /// imported. The same declaration may or may not be included in
+  /// ImportedFromDecls. This map is updated continuously during imports and
+  /// never cleared (like ImportedFromDecls).
+  llvm::DenseMap<Decl *, ImportError> ImportErrors;
+
+  // FIXME put ImportedFromDecls here!
+  // And from that point we can better encapsulate the lookup table.
+
+public:
+  ASTImporterSharedState() = default;
+
+  ASTImporterSharedState(TranslationUnitDecl &ToTU) {
+    LookupTable = llvm::make_unique<ASTImporterLookupTable>(ToTU);
+  }
+
+  ASTImporterLookupTable *getLookupTable() { return LookupTable.get(); }
+
+  void addDeclToLookup(Decl *D) {
+    if (LookupTable)
+      if (auto *ND = dyn_cast<NamedDecl>(D))
+        LookupTable->add(ND);
+  }
+
+  void removeDeclFromLookup(Decl *D) {
+    if (LookupTable)
+      if (auto *ND = dyn_cast<NamedDecl>(D))
+        LookupTable->remove(ND);
+  }
+
+  llvm::Optional<ImportError> getImportDeclErrorIfAny(Decl *ToD) const {
+    auto Pos = ImportErrors.find(ToD);
+    if (Pos != ImportErrors.end())
+      return Pos->second;
+    else
+      return Optional<ImportError>();
+  }
+
+  void setImportDeclError(Decl *To, ImportError Error) {
+    ImportErrors[To] = Error;
+  }
+};
+
+} // namespace clang
+#endif // LLVM_CLANG_AST_ASTIMPORTERSHAREDSTATE_H