Index: include/clang/StaticAnalyzer/Core/BugReporter/BugReporter.h
===================================================================
--- include/clang/StaticAnalyzer/Core/BugReporter/BugReporter.h
+++ include/clang/StaticAnalyzer/Core/BugReporter/BugReporter.h
@@ -95,7 +95,7 @@
   friend class BugReportEquivClass;
   friend class BugReporter;
 
-  BugType& BT;
+  const BugType& BT;
   const Decl *DeclWithIssue = nullptr;
   std::string ShortDescription;
   std::string Description;
@@ -164,15 +164,15 @@
   void popInterestingSymbolsAndRegions();
 
 public:
-  BugReport(BugType& bt, StringRef desc, const ExplodedNode *errornode)
+  BugReport(const BugType& bt, StringRef desc, const ExplodedNode *errornode)
       : BT(bt), Description(desc), ErrorNode(errornode) {}
 
-  BugReport(BugType& bt, StringRef shortDesc, StringRef desc,
+  BugReport(const BugType& bt, StringRef shortDesc, StringRef desc,
             const ExplodedNode *errornode)
       : BT(bt), ShortDescription(shortDesc), Description(desc),
         ErrorNode(errornode) {}
 
-  BugReport(BugType &bt, StringRef desc, PathDiagnosticLocation l)
+  BugReport(const BugType &bt, StringRef desc, PathDiagnosticLocation l)
       : BT(bt), Description(desc), Location(l) {}
 
   /// Create a BugReport with a custom uniqueing location.
@@ -190,7 +190,7 @@
   virtual ~BugReport();
 
   const BugType& getBugType() const { return BT; }
-  BugType& getBugType() { return BT; }
+  //BugType& getBugType() { return BT; }
 
   /// True when the report has an execution path associated with it.
   ///
@@ -481,7 +481,7 @@
     return {};
   }
 
-  void Register(BugType *BT);
+  void Register(const BugType *BT);
 
   /// Add the given report to the set of reports tracked by BugReporter.
   ///
Index: lib/StaticAnalyzer/Checkers/RetainCountChecker/RetainCountDiagnostics.h
===================================================================
--- lib/StaticAnalyzer/Checkers/RetainCountChecker/RetainCountDiagnostics.h
+++ lib/StaticAnalyzer/Checkers/RetainCountChecker/RetainCountDiagnostics.h
@@ -51,7 +51,7 @@
               StringRef endText);
 
   llvm::iterator_range<ranges_iterator> getRanges() override {
-    const RefCountBug& BugTy = static_cast<RefCountBug&>(getBugType());
+    const RefCountBug& BugTy = static_cast<const RefCountBug&>(getBugType());
     if (!BugTy.isLeak())
       return BugReport::getRanges();
     return llvm::make_range(ranges_iterator(), ranges_iterator());
Index: lib/StaticAnalyzer/Core/BugReporter.cpp
===================================================================
--- lib/StaticAnalyzer/Core/BugReporter.cpp
+++ lib/StaticAnalyzer/Core/BugReporter.cpp
@@ -1247,7 +1247,7 @@
 
 static std::unique_ptr<PathDiagnostic>
 generateEmptyDiagnosticForReport(BugReport *R, SourceManager &SM) {
-  BugType &BT = R->getBugType();
+  const BugType &BT = R->getBugType();
   return llvm::make_unique<PathDiagnostic>(
       R->getBugType().getCheckName(), R->getDeclWithIssue(),
       R->getBugType().getName(), R->getDescription(),
@@ -2684,7 +2684,7 @@
   return Out;
 }
 
-void BugReporter::Register(BugType *BT) {
+void BugReporter::Register(const BugType *BT) {
   BugTypes = F.add(BugTypes, BT);
 }
 
@@ -2718,7 +2718,7 @@
   R->Profile(ID);
 
   // Lookup the equivance class.  If there isn't one, create it.
-  BugType& BT = R->getBugType();
+  const BugType& BT = R->getBugType();
   Register(&BT);
   void *InsertPos;
   BugReportEquivClass* EQ = EQClasses.FindNodeOrInsertPos(ID, InsertPos);
@@ -2836,7 +2836,7 @@
                              SmallVectorImpl<BugReport*> &bugReports) {
   BugReportEquivClass::iterator I = EQ.begin(), E = EQ.end();
   assert(I != E);
-  BugType& BT = I->getBugType();
+  const BugType& BT = I->getBugType();
 
   // If we don't need to suppress any of the nodes because they are
   // post-dominated by a sink, simply add all the nodes in the equivalence class