Specialize OwningOpRef::operator-> to work with pointers like Operation*

[mehdi_amini]

Summary

This just simplifies user code.

[rriddle]

Constexpr if?

[mehdi_amini]

Obviously! :)

mlir/include/mlir/IR/OwningOpRef.h

if (op)
       op->erase();
     op = other.release();
     return *this;
   }
 
   /// Allow accessing the internal op.
   OpTy get() const { return op; }
   OpTy operator*() const { return op; }
-  OpTy *operator->() { return &op; }
+  auto operator->() {
+    // Specialize for the case where OpTy is a pointer, to allow using
+    // OwningOpRef<Operation*>.
+    if constexpr (std::is_pointer<OpTy>::value)
+      return op;
+    else
+      return &op;
+  }
   explicit operator bool() const { return op; }
 
   /// Downcast to generic operation.
   operator OwningOpRef<Operation *>() && { return release().getOperation(); }
 
   /// Release the referenced op.
   OpTy release() {
     OpTy released(nullptr);

mlir/lib/Tools/mlir-lsp-server/MLIRServer.cpp

lsp::MLIRServer::convertFromBytecode(const URIForFile &uri) {
   }
 
   // Print the module to a buffer.
   lsp::MLIRConvertBytecodeResult result;
   {
     // Extract the top-level op so that aliases get printed.
     // FIXME: We should be able to enable aliases without having to do this!
     OwningOpRef<Operation *> topOp = &parsedBlock.front();
-    (*topOp)->remove();
+    topOp->remove();
 
     AsmState state(*topOp, OpPrintingFlags().enableDebugInfo().assumeVerified(),
                    /*locationMap=*/nullptr, &fallbackResourceMap);
 
     llvm::raw_string_ostream os(result.output);
-    (*topOp)->print(os, state);
+    topOp->print(os, state);
   }
   return std::move(result);
 }
 
 llvm::Expected<lsp::MLIRConvertBytecodeResult>
 lsp::MLIRServer::convertToBytecode(const URIForFile &uri) {
   auto fileIt = impl->files.find(uri.file());
   if (fileIt == impl->files.end()) {
     return llvm::make_error<lsp::LSPError>(
         "language server does not contain an entry for this source file",
         lsp::ErrorCode::RequestFailed);
   }
   return fileIt->second->convertToBytecode();
 }