[CrossTU] Add a function to retrieve original source location.

[balazske]

Summary

A new function will be added to get the original SourceLocation
for a SourceLocation that was imported as result of getCrossTUDefinition.
The returned SourceLocation is in the context of the (original)
SourceManager for the original source file. Additionally the
ASTUnit object for that source file is returned. This is needed
to get a SourceManager to operate on with the returned source location.

The new function works if multiple different source files are loaded
with the same CrossTU context.

[martong]

LGTM! Thanks!

[martong]

clang/lib/CrossTU/CrossTranslationUnit.cpp

476

The Importer is not used, perhaps it is not needed in the lambda?

Or we might have the mapping of ToID->FromID in the ASTImporter, and the FromID->FromUnit mapping in the CTUContext?

[balazske]

Removed ASTImporter from "callback" function.

[balazske]

clang/lib/CrossTU/CrossTranslationUnit.cpp

476

Yes the Importer is not needed (if needed later it can be added to the lambda as a variable).
Additional mappings of FileID seems not needed now, the current solution is sufficient for this use case. If there is a ToID->FromID in the ASTImporter a "callback" lambda would be still needed to make the FromID->FromUnit mapping.

[balazske]

clang/include/clang/CrossTU/CrossTranslationUnit.h

175 ↗

(On Diff #211024)

It would be better to use std::tuple<SourceLocation, Preprocessor &, ASTContext &> here. (Or * if & does not work.)

[balazske]

Update diff to one commit with all changes.

clang/include/clang/AST/ASTImporter.h

class TypeSourceInfo;
   /// Imports selected nodes from one AST context into another context,
   /// merging AST nodes where appropriate.
   class ASTImporter {
     friend class ASTNodeImporter;
   public:
     using NonEquivalentDeclSet = llvm::DenseSet<std::pair<Decl *, Decl *>>;
     using ImportedCXXBaseSpecifierMap =
         llvm::DenseMap<const CXXBaseSpecifier *, CXXBaseSpecifier *>;
-    using FileIDImportHandlerType = std::function<void(
-        FileID /*ToID*/, FileID /*FromID*/, ASTImporter & /*Importer*/)>;
+    using FileIDImportHandlerType =
+        std::function<void(FileID /*ToID*/, FileID /*FromID*/)>;
 
     // An ImportPath is the list of the AST nodes which we visit during an
     // Import call.
     // If node `A` depends on node `B` then the path contains an `A`->`B` edge.
     // From the call stack of the import functions we can read the very same
     // path.
     //
     // Now imagine the following AST, where the `->` represents dependency in
ASTImporter(ASTContext &ToContext, FileManager &ToFileManager,
                 bool MinimalImport,
                 std::shared_ptr<ASTImporterSharedState> SharedState = nullptr);
 
     virtual ~ASTImporter();
 
     /// Set a callback function for FileID import handling.
     /// The function is invoked when a FileID is imported from the From context.
     /// The imported FileID in the To context and the original FileID in the
-    /// From context, and the ASTImporter itself are passed to it.
+    /// From context is passed to it.
     void setFileIDImportHandler(FileIDImportHandlerType H) {
       FileIDImportHandler = H;
     }
 
     /// Whether the importer will perform a minimal import, creating
     /// to-be-completed forward declarations when possible.
     bool isMinimalImport() const { return Minimal; }
 

clang/lib/AST/ASTImporter.cpp

if (FromSLoc.isExpansion()) {
     }
   }
 
   assert(ToID.isValid() && "Unexpected invalid fileID was created.");
 
   ImportedFileIDs[FromID] = ToID;
 
   if (FileIDImportHandler)
-    FileIDImportHandler(ToID, FromID, *this);
+    FileIDImportHandler(ToID, FromID);
 
   return ToID;
 }
 
 Expected<CXXCtorInitializer *> ASTImporter::Import(CXXCtorInitializer *From) {
   ExpectedExpr ToExprOrErr = Import(From->getInit());
   if (!ToExprOrErr)
     return ToExprOrErr.takeError();

clang/lib/CrossTU/CrossTranslationUnit.cpp

CrossTranslationUnitContext::getOrCreateASTImporter(ASTUnit *Unit) {
 
   auto I = ASTUnitImporterMap.find(From.getTranslationUnitDecl());
   if (I != ASTUnitImporterMap.end())
     return *I->second;
   lazyInitImporterSharedSt(Context.getTranslationUnitDecl());
   ASTImporter *NewImporter = new ASTImporter(
       Context, Context.getSourceManager().getFileManager(), From,
       From.getSourceManager().getFileManager(), false, ImporterSharedSt);
-  NewImporter->setFileIDImportHandler(
-      [this, Unit](FileID ToID, FileID FromID, ASTImporter &Importer) {
-        assert(ImportedFileIDs.find(ToID) == ImportedFileIDs.end() &&
-               "FileID already imported, should not happen.");
-        ImportedFileIDs[ToID] = std::make_pair(FromID, Unit);
-      });
+  NewImporter->setFileIDImportHandler([this, Unit](FileID ToID, FileID FromID) {
   ASTUnitImporterMap[From.getTranslationUnitDecl()].reset(NewImporter);
   return *NewImporter;
 }
 
 llvm::Optional<std::pair<SourceLocation, ASTUnit *>>
 CrossTranslationUnitContext::getImportedFromSourceLocation(
     const clang::SourceLocation &ToLoc) const {
   const SourceManager &SM = Context.getSourceManager();