Apply Clang-Tidy readability-container-size-empty (pytorch#93236)

Not only is this change usually shorter and more readable, it also can yield better performance. size() is not always a constant time operation (such as on LinkedLists), but empty() always is.

Pull Request resolved: pytorch#93236
Approved by: https://github.com/malfet

.clang-tidy

@@ -39,6 +39,7 @@ modernize-*,
 performance-*,
 -performance-noexcept-move-constructor,
 -performance-unnecessary-value-param,
+readability-container-size-empty,
 '
 HeaderFilterRegex: '^(c10/(?!test)|torch/csrc/(?!deploy/interpreter/cpython)).*$'
 AnalyzeTemporaryDtors: false

aten/src/ATen/CPUApplyUtils.h

@@ -106,7 +106,7 @@ struct strided_tensor_iter {
 };
 
 inline bool _all_equal_numel(at::ArrayRef<Tensor> tensors) {
-  if (tensors.size() == 0)
+  if (tensors.empty())
     return true;
   int64_t all_numel = tensors[0].numel();
   for (const auto i : c10::irange(1, tensors.size())) {

aten/src/ATen/FunctionalStorageImpl.cpp

@@ -43,9 +43,10 @@ ViewMeta ViewMeta::to_out_idx(int64_t out_idx) {
 const Tensor apply_update(const FunctionalStorageImpl::Update& update, const Tensor& base) {
   at::Tensor t = update.new_val;
   TORCH_INTERNAL_ASSERT(!at::functionalization::impl::isFunctionalTensor(t));
-  if (update.view_metas.size() == 0) return t;
+  if (update.view_metas.empty()) return t;
 
   std::vector<at::Tensor> tmp_values({base});
+  tmp_values.reserve(update.view_metas.size());
   for (size_t i = 0; i < update.view_metas.size() - 1; ++i) {
     at::Tensor next_view = update.view_metas[i].forward_fn(tmp_values.back(), update.view_metas[i].out_index);
     // NB: We only actually need tmp_values for ops like select/slice/diagonal/squeeze/as_strided
@@ -113,7 +114,7 @@ bool FunctionalStorageImpl::apply_updates() {
   // It adds the Functionalize key into TLS before redispatching to the functionalization kernels,
   // which means that we need to explicitly exclude it here before doing any other work underneath the pass.
   at::AutoDispatchSkipFunctionalize guard;
-  bool any_updates = updates_.size() > 0;
+  bool any_updates = !updates_.empty();
   for (auto& update_data: updates_) {
     base_ = apply_update(update_data, base_);
   }

aten/src/ATen/FunctionalTensorWrapper.cpp

@@ -132,7 +132,7 @@ FunctionalTensorWrapper::FunctionalTensorWrapper(const Tensor& view_value, const
 {
   set_constructor_metadata();
   // Copy the original tensor's ViewMeta vector and push the current one.
-  if (base->view_metas_.size() > 0) {
+  if (!base->view_metas_.empty()) {
       view_metas_ = base->view_metas_;  // copy
   }
   view_metas_.push_back(meta);
@@ -238,7 +238,7 @@ void FunctionalTensorWrapper::maybe_replace_storage(const Tensor& other) {
   //
   // Given all of the above, for now we're just banning the above usage.
   TORCH_CHECK(storage().use_count() == 1, "Attempted to resize a view tensor to a larger size. This is not allowed in the functionalization pass");
-  TORCH_CHECK(view_metas_.size() == 0, "Attempted to resize a view tensor to a larger size. This is not allowed in the functionalization pass");
+  TORCH_CHECK(view_metas_.empty(), "Attempted to resize a view tensor to a larger size. This is not allowed in the functionalization pass");
   // If this tensor is not a view (and has no outstanding views taken out on it),
   // Then it's safe to throw out the old storage and replace it with the new, larger one.
   storage_ = c10::Storage(c10::make_intrusive<functionalization::FunctionalStorageImpl>(other));
@@ -508,7 +508,7 @@ bool isFunctionalTensor(const c10::optional<Tensor>& t) {
 }
 
 bool isFunctionalTensor(const c10::List<c10::optional<Tensor>>& t_list) {
-  if (t_list.size() == 0) return false;
+  if (t_list.empty()) return false;
   auto functional_count = 0;
   for (const auto i : c10::irange(t_list.size())) {
     if (!t_list[i].has_value() || !t_list[i]->defined()) continue;

aten/src/ATen/LegacyBatchedFallback.cpp

@@ -156,7 +156,7 @@ void batchedTensorInplaceForLoopFallback(const c10::OperatorHandle& op, torch::j
     batched_tensor_inputs.push_back(tensor);
     batched_tensor_inputs_position.push_back(idx);
   }
-  TORCH_INTERNAL_ASSERT(batched_tensor_inputs.size() > 0);
+  TORCH_INTERNAL_ASSERT(!batched_tensor_inputs.empty());
 
   // MultiBatchVmapTransform the BatchedTensor arguments. This returns
   // VmapPhysicalViews that contain all of the batch dimensions.
@@ -290,7 +290,7 @@ void batchedTensorForLoopFallback(const c10::OperatorHandle& op, torch::jit::Sta
     batched_tensor_inputs.push_back(tensor);
     batched_tensor_inputs_position.push_back(idx);
   }
-  TORCH_INTERNAL_ASSERT(batched_tensor_inputs.size() > 0);
+  TORCH_INTERNAL_ASSERT(!batched_tensor_inputs.empty());
 
   // MultiBatchVmapTransform the BatchedTensor arguments. This returns
   // VmapPhysicalViews that contain all of the batch dimensions.

aten/src/ATen/LegacyBatchingRegistrations.cpp

@@ -69,7 +69,7 @@ Tensor sum_batching_rule(const Tensor& self, OptionalIntArrayRef opt_dims, bool
     // >>> x = torch.randn(B0)  # the per-examples are all scalars
     // >>> vmap(partial(torch.sum, dim=0), x)
     // then we replicate the behavior of sum(scalar_tensor, dim=0).
-    if (/*logical*/self.dim() == 0 && (dims.size() == 0 || (dims.size() == 1 && is_allowed_dim_on_scalar_tensor(dims[0])))) {
+    if (/*logical*/self.dim() == 0 && (dims.empty() || (dims.size() == 1 && is_allowed_dim_on_scalar_tensor(dims[0])))) {
       return self.clone();
     }
   }
@@ -477,7 +477,7 @@ Tensor view_batching_rule(const Tensor& self, IntArrayRef size) {
 Tensor view_as_complex_batching_rule(const Tensor& self) {
   // guard against the user passing in a batch of scalar tensors with batch
   // size equal to 2.
-  TORCH_CHECK(self.sizes().size() != 0, "Input tensor must have one or more dimensions");
+  TORCH_CHECK(!self.sizes().empty(), "Input tensor must have one or more dimensions");
   auto self_physical = MultiBatchVmapTransform::logicalToPhysical(self);
   auto result = at::view_as_complex(self_physical.tensor());
   return self_physical.getPhysicalToLogicalMap().apply(result);
@@ -931,7 +931,7 @@ Tensor cat_batching_rule(const ITensorListRef& tensors, int64_t dim) {
   auto physical_tensors = fmap(
       physical_views, [](const VmapPhysicalView& view) -> Tensor { return view.tensor(); });
   TORCH_INTERNAL_ASSERT(
-      tensors.size() > 0, "The dispatcher should not have dispatched here otherwise.");
+      !tensors.empty(), "The dispatcher should not have dispatched here otherwise.");
   auto result = at::cat(physical_tensors, physical_views[0].getPhysicalDim(dim));
   return physical_views[0].getPhysicalToLogicalMap().apply(result);
 }
@@ -941,7 +941,7 @@ Tensor stack_batching_rule(TensorList tensors, int64_t dim) {
   auto physical_tensors = fmap(
       physical_views, [](const VmapPhysicalView& view) -> Tensor { return view.tensor(); });
   TORCH_INTERNAL_ASSERT(
-      tensors.size() > 0, "The dispatcher should not have dispatched here otherwise.");
+      !tensors.empty(), "The dispatcher should not have dispatched here otherwise.");
   // NB: stack wraps the dimensionality to (logical dim + 1), so we have to
   // manually handle that here.
   auto dim_physical =

aten/src/ATen/LegacyVmapTransforms.cpp

@@ -239,7 +239,7 @@ MultiBatchVmapTransform::logicalToPhysical(ITensorListRef logical_tensors) {
 
 static std::pair<std::bitset<kVmapNumLevels>,int64_t>
 getLevelsAndLargestLogicalDim(TensorList logical_tensors) {
-  TORCH_INTERNAL_ASSERT(logical_tensors.size() > 0);
+  TORCH_INTERNAL_ASSERT(!logical_tensors.empty());
   std::bitset<kVmapNumLevels> levels;
   int64_t largest_logical_dim = -1;
   for (const auto& tensor : logical_tensors) {

aten/src/ATen/NamedTensorUtils.cpp

@@ -207,7 +207,7 @@ void propagate_names_for_reduction(const Tensor& result, const Tensor& src, IntA
     return;
   }
   // This actually means "full reduction"
-  if (reduced_dims.size() == 0) {
+  if (reduced_dims.empty()) {
     return;
   }
   propagate_names_except(result, src, reduced_dims);
@@ -303,7 +303,7 @@ static int64_t num_batch_dims(DimnameList names) {
 static std::vector<Dimname> compute_matmul_outnames(
     DimnameList self_names,
     DimnameList other_names) {
-  TORCH_CHECK(self_names.size() >= 1 && other_names.size() >= 1,
+  TORCH_CHECK(!self_names.empty() && !other_names.empty(),
       "both arguments to matmul need to be at least 1D, but they are ",
       self_names.size(), "D and ", other_names.size(), "D");
 
@@ -430,7 +430,7 @@ std::vector<Dimname> compute_cat_outnames(const MaterializedITensorListRef& tens
   std::vector<Dimname> result;
   for (const Tensor& tensor : tensors) {
     const auto tensor_names = tensor.names();
-    TORCH_CHECK(tensor_names.size() > 0, "zero-dimensional tensor cannot be concatenated");
+    TORCH_CHECK(!tensor_names.empty(), "zero-dimensional tensor cannot be concatenated");
     TORCH_CHECK(result.empty() || tensor_names.size() == result.size(),
         "Tensors must have same number of dimensions: got ", result.size(),
         " and ", tensor_names.size());

aten/src/ATen/PythonTorchFunctionTLS.cpp

@@ -11,7 +11,7 @@ void PythonTorchFunctionTLS::push_onto_stack(std::shared_ptr<SafePyObject> mode)
 }
 
 const std::shared_ptr<SafePyObject> PythonTorchFunctionTLS::pop_stack() {
-  TORCH_CHECK(pythonTorchFunctionState.stack_.size() > 0, "trying to pop from empty mode stack");
+  TORCH_CHECK(!pythonTorchFunctionState.stack_.empty(), "trying to pop from empty mode stack");
   auto out = pythonTorchFunctionState.stack_.back();
   pythonTorchFunctionState.stack_.pop_back();
   return out;

aten/src/ATen/SavedTensorHooks.cpp

@@ -26,7 +26,7 @@ bool SavedTensorDefaultHooks::is_enabled() {
 
 void SavedTensorDefaultHooks::disable(const std::string& message) {
   tls.disabled_error_message = message;
-  if (tls.stack.size() > 0) {
+  if (!tls.stack.empty()) {
     assertSavedTensorHooksNotDisabled();
   }
 }

aten/src/ATen/TensorIndexing.cpp

@@ -65,7 +65,7 @@ static inline void set_item(const Tensor& self, ArrayRef<TensorIndex> indices, c
 } // namespace indexing
 
 Tensor Tensor::index(ArrayRef<at::indexing::TensorIndex> indices) const {
-  TORCH_CHECK(indices.size() > 0, "Passing an empty index list to Tensor::index() is not valid syntax");
+  TORCH_CHECK(!indices.empty(), "Passing an empty index list to Tensor::index() is not valid syntax");
   OptionalDeviceGuard device_guard(device_of(*this));
   return at::indexing::get_item(*this, indices);
 }
@@ -74,13 +74,13 @@ Tensor Tensor::index(std::initializer_list<at::indexing::TensorIndex> indices) c
 }
 
 Tensor & Tensor::index_put_(ArrayRef<at::indexing::TensorIndex> indices, Tensor const & rhs) {
-  TORCH_CHECK(indices.size() > 0, "Passing an empty index list to Tensor::index_put_() is not valid syntax");
+  TORCH_CHECK(!indices.empty(), "Passing an empty index list to Tensor::index_put_() is not valid syntax");
   OptionalDeviceGuard device_guard(device_of(*this));
   at::indexing::set_item(*this, indices, rhs);
   return *this;
 }
 Tensor & Tensor::index_put_(ArrayRef<at::indexing::TensorIndex> indices, const Scalar& v) {
-  TORCH_CHECK(indices.size() > 0, "Passing an empty index list to Tensor::index_put_() is not valid syntax");
+  TORCH_CHECK(!indices.empty(), "Passing an empty index list to Tensor::index_put_() is not valid syntax");
   OptionalDeviceGuard device_guard(device_of(*this));
   at::indexing::set_item(*this, indices, v);
   return *this;

aten/src/ATen/TensorIndexing.h

@@ -237,7 +237,7 @@ static inline Tensor applySelect(
   // See NOTE [nested tensor size for indexing]
   if (self_sizes.has_value()) {
     TORCH_CHECK_INDEX(
-        !(index == 0 && dim == 0 && self_sizes->size() == 0),
+        !(index == 0 && dim == 0 && self_sizes->empty()),
         "invalid index of a 0-dim tensor. ",
         "Use `tensor.item()` in Python or `tensor.item<T>()` in C++ to convert a 0-dim tensor to a number");
 

aten/src/ATen/TensorIterator.cpp

@@ -163,7 +163,7 @@ TensorIteratorConfig& TensorIteratorConfig::declare_static_shape(IntArrayRef sha
 
 TensorIteratorConfig& TensorIteratorConfig::declare_static_shape(IntArrayRef shape, IntArrayRef squash_dims) {
   declare_static_shape(shape);
-  if (!static_shape_->size()) return *this;
+  if (static_shape_->empty()) return *this;
   for (const auto& squash_dim : squash_dims) {
     TORCH_CHECK(squash_dim >= 0 && squash_dim < static_cast<int64_t>(static_shape_->size()),
                 "squash_dim ", squash_dim, " must be in [0, ", static_shape_->size(), ").");
@@ -715,7 +715,7 @@ void TensorIteratorBase::permute_dimensions(IntArrayRef perm) {
   // Update shape and strides
   shape_ = reorder(shape_);
   for (auto& op : operands_) {
-    if (op.stride_bytes.size() > 0) {
+    if (!op.stride_bytes.empty()) {
       op.stride_bytes = reorder(op.stride_bytes);
     }
   }
@@ -1225,7 +1225,7 @@ void TensorIteratorBase::compute_shape(const TensorIteratorConfig& config) {
       "TensorIterator does not support symbolic shapes; please implement this operator in torch/_refs "
       "using the elementwise or reduction helpers (look at backtrace to find out what operator this is)");
     auto shape = op.tensor_base().sizes();
-    if (shape.size() == 0) {
+    if (shape.empty()) {
       has_scalars = true;
     } else {
       has_tensors = true;
@@ -1724,7 +1724,7 @@ void DimCounter::increment(const std::array<int64_t, 2>& step) {
 std::array<int64_t, 2> DimCounter::max_2d_step() const {
   int64_t step0 = std::min(shape[0] - values[0], range.end - offset);
   int64_t step1 = 1;
-  if (step0 == shape[0] && shape.size() >= 1) {
+  if (step0 == shape[0] && !shape.empty()) {
     step1 = std::min(shape[1] - values[1], (range.end - offset) / shape[0]);
   }
   return {step0, step1};

aten/src/ATen/WrapDimUtils.h

@@ -19,7 +19,7 @@ inline int64_t maybe_wrap_dim(int64_t dim, TensorImpl* tensor) {
 }
 
 inline int64_t maybe_wrap_dim(int64_t dim, TensorList tensors) {
-  if (tensors.size() == 0) {
+  if (tensors.empty()) {
     // can't wrap empty TensorList; rely on underlying implementation to throw
     // error if necessary.
     return dim;
@@ -30,7 +30,7 @@ inline int64_t maybe_wrap_dim(int64_t dim, TensorList tensors) {
 inline int64_t maybe_wrap_dim(
     int64_t dim,
     const std::vector<std::vector<int64_t>>& tensor_sizes) {
-  if (tensor_sizes.size() == 0) {
+  if (tensor_sizes.empty()) {
     // can't wrap empty list; rely on underlying implementation to throw error
     // if necessary
     return dim;

aten/src/ATen/code_template.h

@@ -192,14 +192,14 @@ struct CodeTemplate {
       const string_list& strings,
       bool comma_before,
       bool comma_after) const {
-    if (comma_before && strings.size() > 0)
+    if (comma_before && !strings.empty())
       out << ", ";
     for (const auto i : c10::irange(strings.size())) {
       if (i > 0)
         out << ", ";
       out << strings[i];
     }
-    if (comma_after && strings.size() > 0)
+    if (comma_after && !strings.empty())
       out << ", ";
   }
   // These indentation functions follow the convention that they never emit

aten/src/ATen/core/boxing/impl/boxing.h

@@ -234,7 +234,7 @@ struct BoxedKernelWrapper<
       [&] {
         // op returns void, boxed kernel has pushed nothing onto stack.
         TORCH_INTERNAL_ASSERT_DEBUG_ONLY(
-          stack.size() == 0,
+          stack.empty(),
           "Boxed kernel was expected to return no values on the stack, ",
           "but instead returned ", stack.size(), " values."
         );

aten/src/ATen/core/class_type.cpp

@@ -152,7 +152,7 @@ void checkForwardHookInputArguments(
   if (forward_args.size() == 1) {
     // check for empty forward case
     TORCH_CHECK(
-        input_tuple_types.size() == 0,
+        input_tuple_types.empty(),
         hook_id,
         "was expecting Tuple[()] as the input type. Received type: '",
         input_arg.type()->annotation_str(),
@@ -213,7 +213,7 @@ void ClassType::checkForwardPreHookSchema(
   // or the contained single type if the input was a tuple containing a single
   // type.
   TORCH_CHECK(
-            pre_hook_schema.returns().size() != 0,
+            !pre_hook_schema.returns().empty(),
             hook_id,
             "is missing a return annotation. Return annotations are required, please add one.\n",
             pre_hook_err_msg
@@ -254,7 +254,7 @@ void ClassType::checkForwardPreHookSchema(
   // check for edge case of Tuple[()] for when forward has no arguments
   if (forward_args.size() == 1) {
     TORCH_CHECK(
-        return_tuple_types.size() == 0,
+        return_tuple_types.empty(),
         wrong_type_returned_err_msg,
         " Was expecting either 'None' or 'Tuple[()]' since forward had ",
         "no arguments.\n",

aten/src/ATen/core/dispatch/OperatorEntry.cpp

@@ -145,7 +145,7 @@ OperatorEntry::AnnotatedKernelContainerIterator OperatorEntry::registerKernel(
 #ifdef C10_DISPATCHER_ONE_KERNEL_PER_DISPATCH_KEY
   if (k[0].kernel.isValid()) {
 #else
-  if (k.size() > 0) {
+  if (!k.empty()) {
 #endif
     // Suppress the warning for Meta key as we are overriding C++ meta functions with python meta functions
     // for some ops
@@ -221,12 +221,12 @@ bool OperatorEntry::hasKernelForDispatchKey(DispatchKey k) const {
   TORCH_INTERNAL_ASSERT(kernels_.find(DispatchKey::Undefined) == kernels_.end());
   auto it = kernels_.find(k);
   if (it == kernels_.end()) return false;
-  return it->second.size() > 0;
+  return !it->second.empty();
 }
 
 const KernelFunction& OperatorEntry::kernelForDispatchKey(DispatchKey k) const {
   auto it = kernels_.find(k);
-  TORCH_CHECK(it != kernels_.end() && it->second.size(), "no kernel for ", k, " on ", name_);
+  TORCH_CHECK(it != kernels_.end() && !it->second.empty(), "no kernel for ", k, " on ", name_);
   auto jt = it->second.begin();
   TORCH_INTERNAL_ASSERT(jt->kernel.isValid())
   return jt->kernel;
@@ -462,7 +462,7 @@ void OperatorEntry::checkInvariants() const {
   }
   TORCH_INTERNAL_ASSERT(kernels_.find(DispatchKey::Undefined) == kernels_.end(), dumpState());
   for (const auto& kv : kernels_) {
-    TORCH_INTERNAL_ASSERT(kv.second.size() > 0, dumpState());
+    TORCH_INTERNAL_ASSERT(!kv.second.empty(), dumpState());
   }
   for (auto k : DispatchKeySet(DispatchKeySet::FULL)) {
     auto expected_k = computeDispatchTableEntry(c10::Dispatcher::singleton(), k);

aten/src/ATen/core/dynamic_type.cpp

@@ -38,7 +38,7 @@ std::string DynamicType::str() const {
   std::string ret = "Dynamic<";
   ret += std::to_string(static_cast<DynamicTypeBits>(tag_));
   ret += ">";
-  if (tag_ != Tag::Class && arguments_.elems.size() > 0) {
+  if (tag_ != Tag::Class && !arguments_.elems.empty()) {
     ret += "[";
     for (const auto& arg : arguments_.elems) {
       if (arg.label) {

aten/src/ATen/core/function_schema.cpp

@@ -109,7 +109,7 @@ c10::optional<AliasTypeSet> FunctionSchema::mapTypeToAliasTypeSet(const TypePtr&
               (*maybe_inner_types).end());
         }
       }
-      if (mutable_types.size() == 0) {
+      if (mutable_types.empty()) {
         return c10::nullopt;
       }
       return mutable_types;
@@ -130,7 +130,7 @@ c10::optional<AliasTypeSet> FunctionSchema::mapTypeToAliasTypeSet(const TypePtr&
               (*maybe_inner_types).end());
         }
       }
-      if (mutable_types.size() == 0) {
+      if (mutable_types.empty()) {
         return c10::nullopt;
       }
       return {AliasTypeSet{TupleType::create(std::move(mutable_types))}};