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

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.

Reviewers: martong, shafik

Reviewed By: martong

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

Tags: #clang

Differential Revision: https://reviews.llvm.org/D65064

llvm-svn: 366884

5 files changed, 116 insertions, 18 deletions

diff --git a/clang/include/clang/AST/ASTImporter.h b/clang/include/clang/AST/ASTImporter.h
index 4a55c120a45..12bd5623ec0 100644
--- a/clang/include/clang/AST/ASTImporter.h
+++ b/clang/include/clang/AST/ASTImporter.h
@@ -87,6 +87,8 @@ class TypeSourceInfo;
     using NonEquivalentDeclSet = llvm::DenseSet<std::pair<Decl *, Decl *>>;
     using ImportedCXXBaseSpecifierMap =
         llvm::DenseMap<const CXXBaseSpecifier *, CXXBaseSpecifier *>;
+    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.
@@ -210,6 +212,8 @@ class TypeSourceInfo;
     };
 
   private:
+    FileIDImportHandlerType FileIDImportHandler;
+
     std::shared_ptr<ASTImporterSharedState> SharedState = nullptr;
 
     /// The path which we go through during the import of a given AST node.
@@ -310,6 +314,14 @@ class TypeSourceInfo;
 
     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 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; }
diff --git a/clang/include/clang/CrossTU/CrossTranslationUnit.h b/clang/include/clang/CrossTU/CrossTranslationUnit.h
index d64329cdff3..3e3d2ba70b3 100644
--- a/clang/include/clang/CrossTU/CrossTranslationUnit.h
+++ b/clang/include/clang/CrossTU/CrossTranslationUnit.h
@@ -153,8 +153,10 @@ public:
   ///        was passed to the constructor.
   ///
   /// \return Returns the resulting definition or an error.
-  llvm::Expected<const FunctionDecl *> importDefinition(const FunctionDecl *FD);
-  llvm::Expected<const VarDecl *> importDefinition(const VarDecl *VD);
+  llvm::Expected<const FunctionDecl *> importDefinition(const FunctionDecl *FD,
+                                                        ASTUnit *Unit);
+  llvm::Expected<const VarDecl *> importDefinition(const VarDecl *VD,
+                                                   ASTUnit *Unit);
 
   /// Get a name to identify a named decl.
   static std::string getLookupName(const NamedDecl *ND);
@@ -162,9 +164,23 @@ public:
   /// Emit diagnostics for the user for potential configuration errors.
   void emitCrossTUDiagnostics(const IndexError &IE);
 
+  /// Determine the original source location in the original TU for an
+  /// imported source location.
+  /// \p ToLoc Source location in the imported-to AST.
+  /// \return Source location in the imported-from AST and the corresponding
+  /// ASTUnit object (the AST was loaded from a file using an internal ASTUnit
+  /// object that is returned here).
+  /// If any error happens (ToLoc is a non-imported source location) empty is
+  /// returned.
+  llvm::Optional<std::pair<SourceLocation /*FromLoc*/, ASTUnit *>>
+  getImportedFromSourceLocation(const clang::SourceLocation &ToLoc) const;
+
 private:
+  using ImportedFileIDMap =
+      llvm::DenseMap<FileID, std::pair<FileID, ASTUnit *>>;
+
   void lazyInitImporterSharedSt(TranslationUnitDecl *ToTU);
-  ASTImporter &getOrCreateASTImporter(ASTContext &From);
+  ASTImporter &getOrCreateASTImporter(ASTUnit *Unit);
   template <typename T>
   llvm::Expected<const T *> getCrossTUDefinitionImpl(const T *D,
                                                      StringRef CrossTUDir,
@@ -174,7 +190,7 @@ private:
   const T *findDefInDeclContext(const DeclContext *DC,
                                 StringRef LookupName);
   template <typename T>
-  llvm::Expected<const T *> importDefinitionImpl(const T *D);
+  llvm::Expected<const T *> importDefinitionImpl(const T *D, ASTUnit *Unit);
 
   llvm::StringMap<std::unique_ptr<clang::ASTUnit>> FileASTUnitMap;
   llvm::StringMap<clang::ASTUnit *> NameASTUnitMap;
@@ -184,6 +200,15 @@ private:
   CompilerInstance &CI;
   ASTContext &Context;
   std::shared_ptr<ASTImporterSharedState> ImporterSharedSt;
+  /// Map of imported FileID's (in "To" context) to FileID in "From" context
+  /// and the ASTUnit for the From context.
+  /// This map is used by getImportedFromSourceLocation to lookup a FileID and
+  /// its Preprocessor when knowing only the FileID in the 'To' context. The
+  /// FileID could be imported by any of multiple 'From' ASTImporter objects.
+  /// we do not want to loop over all ASTImporter's to find the one that
+  /// imported the FileID.
+  ImportedFileIDMap ImportedFileIDs;
+
   /// \p CTULoadTreshold should serve as an upper limit to the number of TUs
   /// imported in order to reduce the memory footprint of CTU analysis.
   const unsigned CTULoadThreshold;
diff --git a/clang/lib/AST/ASTImporter.cpp b/clang/lib/AST/ASTImporter.cpp
index 9d5dd84161d..66875f36c55 100644
--- a/clang/lib/AST/ASTImporter.cpp
+++ b/clang/lib/AST/ASTImporter.cpp
@@ -8421,6 +8421,10 @@ Expected<FileID> ASTImporter::Import(FileID FromID, bool IsBuiltin) {
   assert(ToID.isValid() && "Unexpected invalid fileID was created.");
 
   ImportedFileIDs[FromID] = ToID;
+
+  if (FileIDImportHandler)
+    FileIDImportHandler(ToID, FromID);
+
   return ToID;
 }
 
diff --git a/clang/lib/CrossTU/CrossTranslationUnit.cpp b/clang/lib/CrossTU/CrossTranslationUnit.cpp
index 977fd4b8dd3..02fdcbd5815 100644
--- a/clang/lib/CrossTU/CrossTranslationUnit.cpp
+++ b/clang/lib/CrossTU/CrossTranslationUnit.cpp
@@ -295,7 +295,7 @@ llvm::Expected<const T *> CrossTranslationUnitContext::getCrossTUDefinitionImpl(
 
   TranslationUnitDecl *TU = Unit->getASTContext().getTranslationUnitDecl();
   if (const T *ResultDecl = findDefInDeclContext<T>(TU, LookupName))
-    return importDefinition(ResultDecl);
+    return importDefinition(ResultDecl, Unit);
   return llvm::make_error<IndexError>(index_error_code::failed_import);
 }
 
@@ -411,10 +411,13 @@ llvm::Expected<ASTUnit *> CrossTranslationUnitContext::loadExternalAST(
 
 template <typename T>
 llvm::Expected<const T *>
-CrossTranslationUnitContext::importDefinitionImpl(const T *D) {
+CrossTranslationUnitContext::importDefinitionImpl(const T *D, ASTUnit *Unit) {
   assert(hasBodyOrInit(D) && "Decls to be imported should have body or init.");
 
-  ASTImporter &Importer = getOrCreateASTImporter(D->getASTContext());
+  assert(&D->getASTContext() == &Unit->getASTContext() &&
+         "ASTContext of Decl and the unit should match.");
+  ASTImporter &Importer = getOrCreateASTImporter(Unit);
+
   auto ToDeclOrError = Importer.Import(D);
   if (!ToDeclOrError) {
     handleAllErrors(ToDeclOrError.takeError(),
@@ -441,13 +444,15 @@ CrossTranslationUnitContext::importDefinitionImpl(const T *D) {
 }
 
 llvm::Expected<const FunctionDecl *>
-CrossTranslationUnitContext::importDefinition(const FunctionDecl *FD) {
-  return importDefinitionImpl(FD);
+CrossTranslationUnitContext::importDefinition(const FunctionDecl *FD,
+                                              ASTUnit *Unit) {
+  return importDefinitionImpl(FD, Unit);
 }
 
 llvm::Expected<const VarDecl *>
-CrossTranslationUnitContext::importDefinition(const VarDecl *VD) {
-  return importDefinitionImpl(VD);
+CrossTranslationUnitContext::importDefinition(const VarDecl *VD,
+                                              ASTUnit *Unit) {
+  return importDefinitionImpl(VD, Unit);
 }
 
 void CrossTranslationUnitContext::lazyInitImporterSharedSt(
@@ -457,7 +462,9 @@ void CrossTranslationUnitContext::lazyInitImporterSharedSt(
 }
 
 ASTImporter &
-CrossTranslationUnitContext::getOrCreateASTImporter(ASTContext &From) {
+CrossTranslationUnitContext::getOrCreateASTImporter(ASTUnit *Unit) {
+  ASTContext &From = Unit->getASTContext();
+
   auto I = ASTUnitImporterMap.find(From.getTranslationUnitDecl());
   if (I != ASTUnitImporterMap.end())
     return *I->second;
@@ -465,9 +472,32 @@ CrossTranslationUnitContext::getOrCreateASTImporter(ASTContext &From) {
   ASTImporter *NewImporter = new ASTImporter(
       Context, Context.getSourceManager().getFileManager(), From,
       From.getSourceManager().getFileManager(), false, ImporterSharedSt);
+  NewImporter->setFileIDImportHandler([this, Unit](FileID ToID, FileID FromID) {
+    assert(ImportedFileIDs.find(ToID) == ImportedFileIDs.end() &&
+           "FileID already imported, should not happen.");
+    ImportedFileIDs[ToID] = std::make_pair(FromID, Unit);
+  });
   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();
+  auto DecToLoc = SM.getDecomposedLoc(ToLoc);
+
+  auto I = ImportedFileIDs.find(DecToLoc.first);
+  if (I == ImportedFileIDs.end())
+    return {};
+
+  FileID FromID = I->second.first;
+  clang::ASTUnit *Unit = I->second.second;
+  SourceLocation FromLoc =
+      Unit->getSourceManager().getComposedLoc(FromID, DecToLoc.second);
+
+  return std::make_pair(FromLoc, Unit);
+}
+
 } // namespace cross_tu
 } // namespace clang
diff --git a/clang/unittests/CrossTU/CrossTranslationUnitTest.cpp b/clang/unittests/CrossTU/CrossTranslationUnitTest.cpp
index b3e7243ce1d..b4f22d5cb03 100644
--- a/clang/unittests/CrossTU/CrossTranslationUnitTest.cpp
+++ b/clang/unittests/CrossTU/CrossTranslationUnitTest.cpp
@@ -28,13 +28,18 @@ public:
       : CTU(CI), Success(Success) {}
 
   void HandleTranslationUnit(ASTContext &Ctx) {
+    auto FindFInTU = [](const TranslationUnitDecl *TU) {
+      const FunctionDecl *FD = nullptr;
+      for (const Decl *D : TU->decls()) {
+        FD = dyn_cast<FunctionDecl>(D);
+        if (FD && FD->getName() == "f")
+          break;
+      }
+      return FD;
+    };
+
     const TranslationUnitDecl *TU = Ctx.getTranslationUnitDecl();
-    const FunctionDecl *FD = nullptr;
-    for (const Decl *D : TU->decls()) {
-      FD = dyn_cast<FunctionDecl>(D);
-      if (FD && FD->getName() == "f")
-        break;
-    }
+    const FunctionDecl *FD = FindFInTU(TU);
     assert(FD && FD->getName() == "f");
     bool OrigFDHasBody = FD->hasBody();
 
@@ -78,6 +83,28 @@ public:
     if (NewFDorError) {
       const FunctionDecl *NewFD = *NewFDorError;
       *Success = NewFD && NewFD->hasBody() && !OrigFDHasBody;
+
+      if (NewFD) {
+        // Check GetImportedFromSourceLocation.
+        llvm::Optional<std::pair<SourceLocation, ASTUnit *>> SLocResult =
+            CTU.getImportedFromSourceLocation(NewFD->getLocation());
+        EXPECT_TRUE(SLocResult);
+        if (SLocResult) {
+          SourceLocation OrigSLoc = (*SLocResult).first;
+          ASTUnit *OrigUnit = (*SLocResult).second;
+          // OrigUnit is created internally by CTU (is not the
+          // ASTWithDefinition).
+          TranslationUnitDecl *OrigTU =
+              OrigUnit->getASTContext().getTranslationUnitDecl();
+          const FunctionDecl *FDWithDefinition = FindFInTU(OrigTU);
+          EXPECT_TRUE(FDWithDefinition);
+          if (FDWithDefinition) {
+            EXPECT_EQ(FDWithDefinition->getName(), "f");
+            EXPECT_TRUE(FDWithDefinition->isThisDeclarationADefinition());
+            EXPECT_EQ(OrigSLoc, FDWithDefinition->getLocation());
+          }
+        }
+      }
     }
   }