[ASTReader] Add a DeserializationListener callback for IMPORTED_MODULES

Summary:
Add a callback from ASTReader to DeserializationListener when the former
reads an IMPORTED_MODULES block. This supports Swift in using PCH for
bridging headers.

Reviewers: doug.gregor, manmanren, bruno

Reviewed By: manmanren

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D28779

llvm-svn: 292436

2 files changed, 8 insertions, 1 deletions

diff --git a/clang/include/clang/Serialization/ASTDeserializationListener.h b/clang/include/clang/Serialization/ASTDeserializationListener.h
index 4b10c39d8fb..c26f3e0b425 100644
--- a/clang/include/clang/Serialization/ASTDeserializationListener.h
+++ b/clang/include/clang/Serialization/ASTDeserializationListener.h
@@ -26,6 +26,7 @@ class QualType;
 class MacroDefinitionRecord;
 class MacroInfo;
 class Module;
+class SourceLocation;
 
 class ASTDeserializationListener {
 public:
@@ -52,6 +53,9 @@ public:
                                    MacroDefinitionRecord *MD) {}
   /// \brief A module definition was read from the AST file.
   virtual void ModuleRead(serialization::SubmoduleID ID, Module *Mod) {}
+  /// \brief A module import was read from the AST file.
+  virtual void ModuleImportRead(serialization::SubmoduleID ID,
+                                SourceLocation ImportLoc) {}
 };
 }
 
diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index cc78339aa7a..a4da0d2ebe2 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -3251,8 +3251,11 @@ ASTReader::ReadASTBlock(ModuleFile &F, unsigned ClientLoadCapabilities) {
         for (unsigned I = 0, N = Record.size(); I != N; /**/) {
           unsigned GlobalID = getGlobalSubmoduleID(F, Record[I++]);
           SourceLocation Loc = ReadSourceLocation(F, Record, I);
-          if (GlobalID)
+          if (GlobalID) {
             ImportedModules.push_back(ImportedSubmodule(GlobalID, Loc));
+            if (DeserializationListener)
+              DeserializationListener->ModuleImportRead(GlobalID, Loc);
+          }
         }
       }
       break;