diff --git a/flang/include/flang/Evaluate/tools.h b/flang/include/flang/Evaluate/tools.h
--- a/flang/include/flang/Evaluate/tools.h
+++ b/flang/include/flang/Evaluate/tools.h
@@ -583,8 +583,10 @@
 template <TypeCategory TOCAT, typename VALUE>
 common::IfNoLvalue<Expr<SomeKind<TOCAT>>, VALUE> ConvertToKind(
     int kind, VALUE &&x) {
-  return *common::SearchTypes(
-      ConvertToKindHelper<TOCAT, VALUE>{kind, std::move(x)});
+  auto result{common::SearchTypes(
+      ConvertToKindHelper<TOCAT, VALUE>{kind, std::move(x)})};
+  CHECK(result.has_value());
+  return *result;
 }
 
 // Given a type category CAT, SameKindExprs<CAT, N> is a variant that
diff --git a/flang/lib/Lower/Bridge.cpp b/flang/lib/Lower/Bridge.cpp
--- a/flang/lib/Lower/Bridge.cpp
+++ b/flang/lib/Lower/Bridge.cpp
@@ -2769,11 +2769,13 @@
               } else {
                 llvm_unreachable("unknown category");
               }
-              if (lhsIsWholeAllocatable)
+              if (lhsIsWholeAllocatable) {
+                assert(lhsRealloc.has_value());
                 fir::factory::finalizeRealloc(*builder, loc, *lhsMutableBox,
                                               /*lbounds=*/std::nullopt,
                                               /*takeLboundsIfRealloc=*/false,
                                               *lhsRealloc);
+              }
             },
 
             // [2] User defined assignment. If the context is a scalar
diff --git a/flang/lib/Lower/ConvertCall.cpp b/flang/lib/Lower/ConvertCall.cpp
--- a/flang/lib/Lower/ConvertCall.cpp
+++ b/flang/lib/Lower/ConvertCall.cpp
@@ -366,10 +366,12 @@
     callNumResults = call.getNumResults();
   }
 
-  if (caller.mustSaveResult())
+  if (caller.mustSaveResult()) {
+    assert(allocatedResult.has_value());
     builder.create<fir::SaveResultOp>(loc, callResult,
                                       fir::getBase(*allocatedResult),
                                       arrayResultShape, resultLengths);
+  }
 
   if (allocatedResult) {
     allocatedResult->match(
diff --git a/flang/lib/Lower/ConvertExpr.cpp b/flang/lib/Lower/ConvertExpr.cpp
--- a/flang/lib/Lower/ConvertExpr.cpp
+++ b/flang/lib/Lower/ConvertExpr.cpp
@@ -3723,8 +3723,10 @@
       mlir::Value oldInnerArg = modifyOp.getSequence();
       std::size_t offset = explicitSpace->argPosition(oldInnerArg);
       explicitSpace->setInnerArg(offset, fir::getBase(lexv));
-      fir::ExtendedValue exv = arrayModifyToExv(
-          builder, loc, *explicitSpace->getLhsLoad(0), modifyOp.getResult(0));
+      auto lhsLoad = explicitSpace->getLhsLoad(0);
+      assert(lhsLoad.has_value());
+      fir::ExtendedValue exv =
+          arrayModifyToExv(builder, loc, *lhsLoad, modifyOp.getResult(0));
       genScalarUserDefinedAssignmentCall(builder, loc, userAssignment, exv,
                                          elementalExv);
     } else {
@@ -3899,6 +3901,7 @@
     }
     mlir::Value val = builder.createConvert(loc, eleTy, origVal);
     if (isBoundsSpec()) {
+      assert(lbounds.has_value());
       auto lbs = *lbounds;
       if (lbs.size() > 0) {
         // Rebox the value with user-specified shift.
@@ -3908,9 +3911,11 @@
                                            mlir::Value{});
       }
     } else if (isBoundsRemap()) {
+      assert(lbounds.has_value());
       auto lbs = *lbounds;
       if (lbs.size() > 0) {
         // Rebox the value with user-specified shift and shape.
+        assert(ubounds.has_value());
         auto shapeShiftArgs = flatZip(lbs, *ubounds);
         auto shapeTy = fir::ShapeShiftType::get(eleTy.getContext(), lbs.size());
         mlir::Value shapeShift =
@@ -6298,6 +6303,7 @@
         charLen = builder.createTemporary(loc, builder.getI64Type());
         mlir::Value castLen =
             builder.createConvert(loc, builder.getI64Type(), fir::getLen(exv));
+        assert(charLen.has_value());
         builder.create<fir::StoreOp>(loc, castLen, *charLen);
       }
     }
@@ -6312,6 +6318,7 @@
 
     // Convert to extended value.
     if (fir::isa_char(seqTy.getEleTy())) {
+      assert(charLen.has_value());
       auto len = builder.create<fir::LoadOp>(loc, *charLen);
       return {fir::CharArrayBoxValue{mem, len, extents}, /*needCopy=*/false};
     }
diff --git a/flang/lib/Lower/ConvertExprToHLFIR.cpp b/flang/lib/Lower/ConvertExprToHLFIR.cpp
--- a/flang/lib/Lower/ConvertExprToHLFIR.cpp
+++ b/flang/lib/Lower/ConvertExprToHLFIR.cpp
@@ -820,8 +820,10 @@
   gen(const Fortran::evaluate::FunctionRef<T> &expr) {
     mlir::Type resType =
         Fortran::lower::TypeBuilder<T>::genType(getConverter(), expr);
-    return *Fortran::lower::convertCallToHLFIR(
+    auto result = Fortran::lower::convertCallToHLFIR(
         getLoc(), getConverter(), expr, resType, getSymMap(), getStmtCtx());
+    assert(result.has_value());
+    return *result;
   }
 
   template <typename T>
diff --git a/flang/lib/Lower/CustomIntrinsicCall.cpp b/flang/lib/Lower/CustomIntrinsicCall.cpp
--- a/flang/lib/Lower/CustomIntrinsicCall.cpp
+++ b/flang/lib/Lower/CustomIntrinsicCall.cpp
@@ -179,8 +179,10 @@
   llvm::SmallVector<fir::ExtendedValue> args;
   args.push_back(getOperand(0));
   args.push_back(getOperand(1));
+  auto iPC = isPresentCheck(2);
+  assert(iPC.has_value());
   args.push_back(builder
-                     .genIfOp(loc, {resultType}, *isPresentCheck(2),
+                     .genIfOp(loc, {resultType}, *iPC,
                               /*withElseRegion=*/true)
                      .genThen([&]() {
                        fir::ExtendedValue sizeExv = getOperand(2);