Fixup c10 headers with clang-tidy (#91407)

Clang-tidy was not applied properly to headers in c10 as documented #91406. These are the easy automated fixes that came out of applying clang-tidy to the c10 part of the code base. cc @ezyang
Pull Request resolved: https://github.com/pytorch/pytorch/pull/91407
Approved by: https://github.com/ezyang

c10/core/Allocator.h

@@ -226,7 +226,7 @@ struct AllocatorRegisterer {
 // per device
 struct C10_API MemoryReportingInfoBase : public c10::DebugInfoBase {
   MemoryReportingInfoBase();
-  virtual ~MemoryReportingInfoBase() {}
+  ~MemoryReportingInfoBase() override = default;
 
   /**
    * alloc_size corresponds to the size of the ptr.

c10/core/DispatchKeySet.h

@@ -14,12 +14,12 @@ struct FunctionalityOffsetAndMask {
   FunctionalityOffsetAndMask(uint16_t offset, uint16_t mask)
       : offset(offset), mask(mask) {}
   // This needs to big enough to cover the size of the operator table.
-  uint16_t offset;
+  uint16_t offset{};
   // See Note [No More Than 16 Backends]
   // This mask needs to be big enough to mask all of the backend bits.
   // We probably don't ever want to have more than 16 backend bits, so uint16_t
   // should be enough.
-  uint16_t mask;
+  uint16_t mask{};
 };
 static_assert(
     c10::num_runtime_entries < 65536,

c10/core/InferenceMode.h

@@ -66,7 +66,7 @@ struct TORCH_API InferenceMode {
     DispatchKeySet excluded = enabled
         ? (prev_keyset.excluded_ | c10::autograd_dispatch_keyset)
         : (prev_keyset.excluded_ - c10::autograd_dispatch_keyset);
-    c10::impl::PODLocalDispatchKeySet cur_keyset;
+    c10::impl::PODLocalDispatchKeySet cur_keyset{};
     cur_keyset.set_included(included);
     cur_keyset.set_excluded(excluded);
     c10::impl::_force_tls_local_dispatch_key_set(cur_keyset);

c10/core/Scalar.h

@@ -292,7 +292,7 @@ class C10_API Scalar {
   Tag tag;
 
   union v_t {
-    double d;
+    double d{};
     int64_t i;
     c10::complex<double> z;
     c10::intrusive_ptr_target* p;

c10/core/SymIntArrayRef.h

@@ -19,7 +19,7 @@ inline at::IntArrayRef asIntArrayRefUnchecked(c10::SymIntArrayRef ar) {
 
 inline c10::optional<at::IntArrayRef> asIntArrayRefSlowOpt(
     c10::SymIntArrayRef ar) {
-  for (c10::SymInt sci : ar) {
+  for (const c10::SymInt& sci : ar) {
     if (sci.is_symbolic()) {
       return c10::nullopt;
     }
@@ -32,7 +32,7 @@ inline at::IntArrayRef asIntArrayRefSlow(
     c10::SymIntArrayRef ar,
     const char* file,
     int64_t line) {
-  for (c10::SymInt sci : ar) {
+  for (const c10::SymInt& sci : ar) {
     TORCH_CHECK(
         !sci.is_symbolic(),
         file,

c10/core/TensorOptions.h

@@ -582,7 +582,7 @@ inline TensorOptions layout(Layout layout) {
 /// Convenience function that returns a `TensorOptions` object with the `device`
 /// set to the given one.
 inline TensorOptions device(Device device) {
-  return TensorOptions().device(std::move(device));
+  return TensorOptions().device(device);
 }
 
 /// Convenience function that returns a `TensorOptions` object with the

c10/util/Array.h

@@ -76,8 +76,8 @@ struct __array_traits<_Tp, 0> final {
   }
 };
 
-[[noreturn]] inline void __throw_out_of_range(std::string msg) {
+[[noreturn]] inline void __throw_out_of_range(const std::string& msg) {
-  throw std::out_of_range(std::move(msg));
+  throw std::out_of_range(msg);
 }
 } // namespace detail
 

c10/util/BFloat16-inl.h

@@ -11,14 +11,16 @@ C10_CLANG_DIAGNOSTIC_IGNORE("-Wimplicit-int-float-conversion")
 namespace c10 {
 
 /// Constructors
-inline C10_HOST_DEVICE BFloat16::BFloat16(float value) {
+inline C10_HOST_DEVICE BFloat16::BFloat16(float value)
+    :
 #if defined(CUDA_VERSION) && CUDA_VERSION >= 11000 && \
     defined(__CUDA_ARCH__) && __CUDA_ARCH__ >= 800
-  x = __bfloat16_as_ushort(__float2bfloat16(value));
+      x(__bfloat16_as_ushort(__float2bfloat16(value)))
 #else
-  // RNE by default
+      // RNE by default
-  x = detail::round_to_nearest_even(value);
+      x(detail::round_to_nearest_even(value))
 #endif
+{
 }
 
 /// Implicit conversions

c10/util/Half-inl.h

@@ -27,14 +27,16 @@ namespace c10 {
 
 /// Constructors
 
-inline C10_HOST_DEVICE Half::Half(float value) {
+inline C10_HOST_DEVICE Half::Half(float value)
+    :
 #if defined(__CUDA_ARCH__) || defined(__HIP_DEVICE_COMPILE__)
-  x = __half_as_short(__float2half(value));
+      x(__half_as_short(__float2half(value)))
 #elif defined(__SYCL_DEVICE_ONLY__)
-  x = sycl::bit_cast<uint16_t>(sycl::half(value));
+      x(sycl::bit_cast<uint16_t>(sycl::half(value)))
 #else
-  x = detail::fp16_ieee_from_fp32_value(value);
+      x(detail::fp16_ieee_from_fp32_value(value))
 #endif
+{
 }
 
 /// Implicit conversions

c10/util/Optional.h

@@ -172,7 +172,7 @@ class bad_optional_access : public std::logic_error {
 
 template <class T>
 union storage_t {
-  unsigned char dummy_;
+  unsigned char dummy_{};
   T value_;
 
 #if __cplusplus >= 202002L

c10/util/SmallVector.h

@@ -451,7 +451,7 @@ class SmallVectorTemplateBase : public SmallVectorTemplateCommon<T> {
 
   void growAndAssign(size_t NumElts, const T& Elt) {
     // Grow manually in case Elt is an internal reference.
-    size_t NewCapacity;
+    size_t NewCapacity = 0;
     T* NewElts = mallocForGrow(NumElts, NewCapacity);
     std::uninitialized_fill_n(NewElts, NumElts, Elt);
     this->destroy_range(this->begin(), this->end());
@@ -462,7 +462,7 @@ class SmallVectorTemplateBase : public SmallVectorTemplateCommon<T> {
   template <typename... ArgTypes>
   T& growAndEmplaceBack(ArgTypes&&... Args) {
     // Grow manually in case one of Args is an internal reference.
-    size_t NewCapacity;
+    size_t NewCapacity = 0;
     T* NewElts = mallocForGrow(0, NewCapacity);
     ::new ((void*)(NewElts + this->size())) T(std::forward<ArgTypes>(Args)...);
     moveElementsForGrow(NewElts);
@@ -493,7 +493,7 @@ class SmallVectorTemplateBase : public SmallVectorTemplateCommon<T> {
 // Define this out-of-line to dissuade the C++ compiler from inlining it.
 template <typename T, bool TriviallyCopyable>
 void SmallVectorTemplateBase<T, TriviallyCopyable>::grow(size_t MinSize) {
-  size_t NewCapacity;
+  size_t NewCapacity = 0;
   T* NewElts = mallocForGrow(MinSize, NewCapacity);
   moveElementsForGrow(NewElts);
   takeAllocationForGrow(NewElts, NewCapacity);

c10/util/string_view.h

@@ -668,7 +668,7 @@ class basic_string_view final {
   };
 
   const_pointer begin_;
-  size_type size_;
+  size_type size_{};
 };
 
 template <class CharT>