Restore diagnostic handler after CodeGenAction::ExecuteAction

[mantognini]

Summary

Fix dangling pointer to local variable and address some typos.

[mantognini]

llvm/include/llvm/IR/LLVMContext.h

196

Had to run clang-format. The change is replacing "third" with "second".

[xur]

This looks fine to me. Thanks for fixing.

clang/lib/CodeGen/CodeGenAction.cpp

if (TheModule->getTargetTriple() != TargetOpts.Triple) {
     TheModule->setTargetTriple(TargetOpts.Triple);
   }
 
   EmbedBitcode(TheModule.get(), CodeGenOpts, *MainFile);
 
   LLVMContext &Ctx = TheModule->getContext();
   Ctx.setInlineAsmDiagnosticHandler(BitcodeInlineAsmDiagHandler, &Diagnostics);
 
+  // Restore any diagnostic handler previously set before returning from this
+  // function.
+  struct RAII {
+    LLVMContext &Ctx;
+    std::unique_ptr<DiagnosticHandler> PrevHandler = Ctx.getDiagnosticHandler();
+    ~RAII() { Ctx.setDiagnosticHandler(std::move(PrevHandler)); }
+  } _{Ctx};
+
   // Set clang diagnostic handler. To do this we need to create a fake
   // BackendConsumer.
   BackendConsumer Result(BA, CI.getDiagnostics(), CI.getHeaderSearchOpts(),
                          CI.getPreprocessorOpts(), CI.getCodeGenOpts(),
                          CI.getTargetOpts(), CI.getLangOpts(),
                          std::move(LinkModules), *VMContext, nullptr);
   // PR44896: Force DiscardValueNames as false. DiscardValueNames cannot be
   // true here because the valued names are needed for reading textual IR.

llvm/include/llvm/IR/LLVMContext.h

#undef LLVM_FIXED_MD_KIND
   /// true if the handler only expects enabled diagnostics.
   ///
   /// LLVMContext doesn't take ownership or interpret either of these
   /// pointers.
   void setDiagnosticHandlerCallBack(
       DiagnosticHandler::DiagnosticHandlerTy DiagHandler,
       void *DiagContext = nullptr, bool RespectFilters = false);
 
-  /// setDiagnosticHandler - This method sets unique_ptr to object of DiagnosticHandler
-  /// to provide custom diagnostic handling. The first argument is unique_ptr of object
-  /// of type DiagnosticHandler or a derived of that.   The third argument should be
-  /// set to true if the handler only expects enabled diagnostics.
+  /// setDiagnosticHandler - This method sets unique_ptr to object of
+  /// DiagnosticHandler to provide custom diagnostic handling. The first
+  /// argument is unique_ptr of object of type DiagnosticHandler or a derived
+  /// of that. The second argument should be set to true if the handler only
+  /// expects enabled diagnostics.
   ///
   /// Ownership of this pointer is moved to LLVMContextImpl.
   void setDiagnosticHandler(std::unique_ptr<DiagnosticHandler> &&DH,
                             bool RespectFilters = false);
 
   /// getDiagnosticHandlerCallBack - Return the diagnostic handler call back set by
   /// setDiagnosticHandlerCallBack.
   DiagnosticHandler::DiagnosticHandlerTy getDiagnosticHandlerCallBack() const;
 
   /// getDiagnosticContext - Return the diagnostic context set by
   /// setDiagnosticContext.
   void *getDiagnosticContext() const;
 
   /// getDiagHandlerPtr - Returns const raw pointer of DiagnosticHandler set by
   /// setDiagnosticHandler.
   const DiagnosticHandler *getDiagHandlerPtr() const;
 
-  /// getDiagnosticHandler - transfers owenership of DiagnosticHandler unique_ptr
+  /// getDiagnosticHandler - transfers ownership of DiagnosticHandler unique_ptr
   /// to caller.
   std::unique_ptr<DiagnosticHandler> getDiagnosticHandler();
 
   /// Return if a code hotness metric should be included in optimization
   /// diagnostics.
   bool getDiagnosticsHotnessRequested() const;
   /// Set if a code hotness metric should be included in optimization
   /// diagnostics.