Add testcase for C++ chained PCH and fix the bugs it uncovered in name lookup.

llvm-svn: 111882

2 files changed, 7 insertions, 15 deletions

diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index 8167a0f5faf..38b343ffe83 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -3192,9 +3192,10 @@ ASTReader::FindExternalVisibleDeclsByName(const DeclContext *DC,
 
   llvm::SmallVector<NamedDecl *, 64> Decls;
   // There might be visible decls in multiple parts of the chain, for the TU
-  // and namespaces.
+  // and namespaces. For any given name, the last available results replace
+  // all earlier ones. For this reason, we walk in reverse.
   DeclContextInfos &Infos = DeclContextOffsets[DC];
-  for (DeclContextInfos::iterator I = Infos.begin(), E = Infos.end();
+  for (DeclContextInfos::reverse_iterator I = Infos.rbegin(), E = Infos.rend();
        I != E; ++I) {
     if (!I->NameLookupTableData)
       continue;
@@ -3208,6 +3209,7 @@ ASTReader::FindExternalVisibleDeclsByName(const DeclContext *DC,
     ASTDeclContextNameLookupTrait::data_type Data = *Pos;
     for (; Data.first != Data.second; ++Data.first)
       Decls.push_back(cast<NamedDecl>(GetDecl(*Data.first)));
+    break;
   }
 
   ++NumVisibleDeclContextsRead;
diff --git a/clang/lib/Serialization/ASTWriter.cpp b/clang/lib/Serialization/ASTWriter.cpp
index dc9f4d409af..43bb7ad4c7a 100644
--- a/clang/lib/Serialization/ASTWriter.cpp
+++ b/clang/lib/Serialization/ASTWriter.cpp
@@ -2101,23 +2101,13 @@ void ASTWriter::WriteDeclContextVisibleUpdate(const DeclContext *DC) {
   ASTDeclContextNameLookupTrait Trait(*this);
 
   // Create the hash table.
-  llvm::SmallVector<NamedDecl *, 16> Decls;
   for (StoredDeclsMap::iterator D = Map->begin(), DEnd = Map->end();
        D != DEnd; ++D) {
     DeclarationName Name = D->first;
     DeclContext::lookup_result Result = D->second.getLookupResult();
-    // Need to filter these results to only include decls that are not from
-    // an existing PCH.
-    Decls.clear();
-    for (; Result.first != Result.second; ++Result.first) {
-      if ((*Result.first)->getPCHLevel() == 0)
-        Decls.push_back(*Result.first);
-    }
-    if (!Decls.empty()) {
-      Result.first = Decls.data();
-      Result.second = Result.first + Decls.size();
-      Generator.insert(Name, Result, Trait);
-    }
+    // For any name that appears in this table, the results are complete, i.e.
+    // they overwrite results from previous PCHs. Merging is always a mess.
+    Generator.insert(Name, Result, Trait);
   }
 
   // Create the on-disk hash table in a buffer.