2 files changed, 11 insertions, 2 deletions
diff --git a/llvm/include/llvm/ProfileData/Coverage/CoverageMappingWriter.h b/llvm/include/llvm/ProfileData/Coverage/CoverageMappingWriter.h
index 5f88cacdfcb..6fcd8a09a49 100644
--- a/llvm/include/llvm/ProfileData/Coverage/CoverageMappingWriter.h
+++ b/llvm/include/llvm/ProfileData/Coverage/CoverageMappingWriter.h
@@ -30,8 +30,7 @@ class CoverageFilenamesSectionWriter {
   ArrayRef<StringRef> Filenames;
 
 public:
-  CoverageFilenamesSectionWriter(ArrayRef<StringRef> Filenames)
-      : Filenames(Filenames) {}
+  CoverageFilenamesSectionWriter(ArrayRef<StringRef> Filenames);
 
   /// Write encoded filenames to the given output stream.
   void write(raw_ostream &OS);
diff --git a/llvm/lib/ProfileData/Coverage/CoverageMappingWriter.cpp b/llvm/lib/ProfileData/Coverage/CoverageMappingWriter.cpp
index 432b20f217c..d75854a60d1 100644
--- a/llvm/lib/ProfileData/Coverage/CoverageMappingWriter.cpp
+++ b/llvm/lib/ProfileData/Coverage/CoverageMappingWriter.cpp
@@ -24,6 +24,16 @@
 using namespace llvm;
 using namespace coverage;
 
+CoverageFilenamesSectionWriter::CoverageFilenamesSectionWriter(
+    ArrayRef<StringRef> Filenames)
+    : Filenames(Filenames) {
+#ifndef NDEBUG
+  StringSet<> NameSet;
+  for (StringRef Name : Filenames)
+    assert(NameSet.insert(Name).second && "Duplicate filename");
+#endif
+}
+
 void CoverageFilenamesSectionWriter::write(raw_ostream &OS) {
   encodeULEB128(Filenames.size(), OS);
   for (const auto &Filename : Filenames) {