Fix some compiler warnings

lib/Dialect/Arc/Transforms/ArcCanonicalizer.cpp

@@ -49,7 +49,8 @@ public:
   /// Return the users of the provided symbol operation.
   ArrayRef<Operation *> getUsers(Operation *symbol) const {
     auto it = userMap.find(symbol);
-    return it != userMap.end() ? it->second.getArrayRef() : std::nullopt;
+    return it != userMap.end() ? it->second.getArrayRef()
+                               : ArrayRef<Operation *>();
   }
 
   /// Return true if the given symbol has no uses.

lib/Dialect/FSM/FSMOps.cpp

@@ -46,7 +46,7 @@ void MachineOp::build(OpBuilder &builder, OperationState &state, StringRef name,
   assert(type.getNumInputs() == argAttrs.size());
   call_interface_impl::addArgAndResultAttrs(
       builder, state, argAttrs,
-      /*resultAttrs=*/std::nullopt, MachineOp::getArgAttrsAttrName(state.name),
+      /*resultAttrs=*/{}, MachineOp::getArgAttrsAttrName(state.name),
       MachineOp::getResAttrsAttrName(state.name));
 }
 

lib/Dialect/Handshake/Transforms/LowerExtmemToHW.cpp

@@ -420,10 +420,13 @@ HandshakeLowerExtmemToHWPass::lowerExtmemToHW(handshake::FuncOp func) {
     llvm::SmallVector<Value> newReturnOperands = oldReturnOp.getOperands();
     unsigned addedInPorts = 0;
     auto memName = func.getArgName(i);
-    auto addArgRes = [&](unsigned id, NamedType &argType, NamedType &resType) {
+    auto addArgRes = [&](unsigned id, NamedType &argType,
+                         NamedType &resType) -> FailureOr<Value> {
       // Function argument
       unsigned newArgIdx = i + addedInPorts;
-      func.insertArgument(newArgIdx, argType.second, {}, arg.getLoc());
+      if (failed(
+              func.insertArgument(newArgIdx, argType.second, {}, arg.getLoc())))
+        return failure();
       insertInStringArrayAttr(func, "argNames",
                               memName.str() + "_" + argType.first.str(),
                               newArgIdx);
@@ -431,7 +434,8 @@ HandshakeLowerExtmemToHWPass::lowerExtmemToHW(handshake::FuncOp func) {
       ++addedInPorts;
 
       // Function result.
-      func.insertResult(func.getNumResults(), resType.second, {});
+      if (failed(func.insertResult(func.getNumResults(), resType.second, {})))
+        return failure();
       appendToStringArrayAttr(func, "resNames",
                               memName.str() + "_" + resType.first.str());
       return newInPort;
@@ -442,8 +446,10 @@ HandshakeLowerExtmemToHWPass::lowerExtmemToHW(handshake::FuncOp func) {
     for (auto loadPort : extmemOp.getLoadPorts()) {
       auto newInPort = addArgRes(loadPort.index, memIOTypes.inputTypes[portIdx],
                                  memIOTypes.outputTypes[portIdx]);
+      if (failed(newInPort))
+        return failure();
       newReturnOperands.push_back(
-          plumbLoadPort(loc, b, loadPort, newInPort, memrefType));
+          plumbLoadPort(loc, b, loadPort, *newInPort, memrefType));
       ++portIdx;
     }
 
@@ -452,8 +458,10 @@ HandshakeLowerExtmemToHWPass::lowerExtmemToHW(handshake::FuncOp func) {
       auto newInPort =
           addArgRes(storePort.index, memIOTypes.inputTypes[portIdx],
                     memIOTypes.outputTypes[portIdx]);
+      if (failed(newInPort))
+        return failure();
       newReturnOperands.push_back(
-          plumbStorePort(loc, b, storePort, newInPort,
+          plumbStorePort(loc, b, storePort, *newInPort,
                          memIOTypes.outputTypes[portIdx].second, memrefType));
       ++portIdx;
     }
@@ -470,7 +478,8 @@ HandshakeLowerExtmemToHWPass::lowerExtmemToHW(handshake::FuncOp func) {
 
     // Erase the original memref argument of the top-level i/o now that it's
     // use has been removed.
-    func.eraseArgument(i + addedInPorts);
+    if (failed(func.eraseArgument(i + addedInPorts)))
+      return failure();
     eraseFromArrayAttr(func, "argNames", i + addedInPorts);
 
     argReplacements[i] = memIOTypes;

lib/Reduce/Tester.cpp

@@ -48,7 +48,7 @@ bool Tester::isInteresting(StringRef testCase) const {
   // Run the tester.
   std::string errMsg;
   int result = llvm::sys::ExecuteAndWait(
-      testScript, testerArgs, /*Env=*/std::nullopt, /*Redirects=*/std::nullopt,
+      testScript, testerArgs, /*Env=*/std::nullopt, /*Redirects=*/{},
       /*SecondsToWait=*/0, /*MemoryLimit=*/0, &errMsg);
   if (result < 0)
     llvm::report_fatal_error(