1 files changed, 20 insertions, 0 deletions
diff --git a/clang/lib/Format/UsingDeclarationsSorter.cpp b/clang/lib/Format/UsingDeclarationsSorter.cpp
index 2c124ec78b1..ef0c7a7d5a4 100644
--- a/clang/lib/Format/UsingDeclarationsSorter.cpp
+++ b/clang/lib/Format/UsingDeclarationsSorter.cpp
@@ -130,7 +130,27 @@ void endUsingDeclarationBlock(
       UsingDeclarations->begin(), UsingDeclarations->end());
   std::stable_sort(SortedUsingDeclarations.begin(),
                    SortedUsingDeclarations.end());
+  SortedUsingDeclarations.erase(
+      std::unique(SortedUsingDeclarations.begin(),
+                  SortedUsingDeclarations.end(),
+                  [](const UsingDeclaration &a, const UsingDeclaration &b) {
+                    return a.Label == b.Label;
+                  }),
+      SortedUsingDeclarations.end());
   for (size_t I = 0, E = UsingDeclarations->size(); I < E; ++I) {
+    if (I >= SortedUsingDeclarations.size()) {
+      // This using declaration has been deduplicated, delete it.
+      auto Begin =
+          (*UsingDeclarations)[I].Line->First->WhitespaceRange.getBegin();
+      auto End = (*UsingDeclarations)[I].Line->Last->Tok.getEndLoc();
+      auto Range = CharSourceRange::getCharRange(Begin, End);
+      auto Err = Fixes->add(tooling::Replacement(SourceMgr, Range, ""));
+      if (Err) {
+        llvm::errs() << "Error while sorting using declarations: "
+                     << llvm::toString(std::move(Err)) << "\n";
+      }
+      continue;
+    }
     if ((*UsingDeclarations)[I].Line == SortedUsingDeclarations[I].Line)
       continue;
     auto Begin = (*UsingDeclarations)[I].Line->First->Tok.getLocation();