Apply clang-tidy modernize-concat-nested-namespaces

Summary: Apply [modernize-concat-nested-namespaces](https://clang.llvm.org/extra/clang-tidy/checks/modernize/concat-nested-namespaces.html)(C++17) check to `thrift/lib/cpp2`.

Reviewed By: rmakheja

Differential Revision: D64049325

fbshipit-source-id: 042570700b75602634a2c71e834a55c0e9847860

third-party/thrift/src/thrift/lib/cpp2/BadFieldAccess.h

@@ -18,8 +18,7 @@
 
 #include <stdexcept>
 
-namespace apache {
-namespace thrift {
+namespace apache::thrift {
 
 // Base exception type for field access errors
 class bad_field_access : public std::runtime_error {
@@ -43,5 +42,4 @@ class bad_union_field_access : public bad_field_access {
       : bad_field_access("accessing unset or mismatched type union value") {}
 };
 
-} // namespace thrift
-} // namespace apache
+} // namespace apache::thrift

third-party/thrift/src/thrift/lib/cpp2/TypeClass.h

@@ -16,8 +16,7 @@
 
 #pragma once
 
-namespace apache {
-namespace thrift {
+namespace apache::thrift {
 
 /**
  * The type class of a type as declared in a .thrift file.
@@ -101,5 +100,4 @@ namespace detail {
 template <typename TypeClass, typename Indirection>
 struct indirection_tag;
 } // namespace detail
-} // namespace thrift
-} // namespace apache
+} // namespace apache::thrift

third-party/thrift/src/thrift/lib/cpp2/debug_thrift_data_difference/detail/debug-inl-pre.h

@@ -18,13 +18,9 @@
 
 #include <string>
 
-namespace facebook {
-namespace thrift {
-namespace detail {
+namespace facebook::thrift::detail {
 
 template <typename Tag, typename T, typename Callback>
 bool debug_thrift_data_difference(std::string&, T const&, T const&, Callback&&);
 
-} // namespace detail
-} // namespace thrift
-} // namespace facebook
+} // namespace facebook::thrift::detail

third-party/thrift/src/thrift/lib/cpp2/debug_thrift_data_difference/detail/pretty_print-inl-pre.h

@@ -16,13 +16,9 @@
 
 #pragma once
 
-namespace facebook {
-namespace thrift {
-namespace detail {
+namespace facebook::thrift::detail {
 
 template <typename>
 struct pretty_print_impl;
 
-} // namespace detail
-} // namespace thrift
-} // namespace facebook
+} // namespace facebook::thrift::detail

third-party/thrift/src/thrift/lib/cpp2/folly_dynamic/internal/folly_dynamic-inl-pre.h

@@ -16,13 +16,9 @@
 
 #pragma once
 
-namespace facebook {
-namespace thrift {
-namespace detail {
+namespace facebook::thrift::detail {
 
 template <typename, typename = void>
 struct dynamic_converter_impl;
 
-} // namespace detail
-} // namespace thrift
-} // namespace facebook
+} // namespace facebook::thrift::detail

third-party/thrift/src/thrift/lib/cpp2/frozen/Traits.h

@@ -17,8 +17,7 @@
 #pragma once
 #include <type_traits>
 
-namespace apache {
-namespace thrift {
+namespace apache::thrift {
 
 template <class>
 struct IsString : std::false_type {};
@@ -40,8 +39,7 @@ template <class>
 struct IsExcluded : std::false_type {};
 } // namespace frozen
 
-} // namespace thrift
-} // namespace apache
+} // namespace apache::thrift
 
 #define THRIFT_DECLARE_TRAIT(Trait, ...)         \
   namespace apache {                             \

third-party/thrift/src/thrift/lib/cpp2/protocol/detail/ReservedId.h

@@ -18,9 +18,7 @@
 
 #include <cstdint>
 
-namespace apache {
-namespace thrift {
-namespace detail {
+namespace apache::thrift::detail {
 enum class ReservedId : int16_t {
   kOffset = -32768, // Lazy deserialization
   kIndex = -32767, // Lazy deserialization
@@ -30,6 +28,4 @@ enum class ReservedId : int16_t {
   kInjectMetadataFieldsLastId = -2000, // @internal.InjectMetadataFields
   kInjectMetadataFieldsStartId = -1000, // @internal.InjectMetadataFields
 };
-} // namespace detail
-} // namespace thrift
-} // namespace apache
+} // namespace apache::thrift::detail

third-party/thrift/src/thrift/lib/cpp2/reflection/indenter.h

@@ -23,8 +23,7 @@
 #include <utility>
 #include <vector>
 
-namespace apache {
-namespace thrift {
+namespace apache::thrift {
 
 /**
  * Wraps a stream and provides facilities for automatically indenting output.
@@ -154,7 +153,6 @@ indenter<std::remove_reference_t<OutputStream>> make_indenter(
   return {out, std::forward<Indentation>(indentation), std::move(margin)};
 }
 
-} // namespace thrift
-} // namespace apache
+} // namespace apache::thrift
 
 #endif // THRIFT_FATAL_INDENTER_H_

third-party/thrift/src/thrift/lib/cpp2/reflection/internal/legacy_reflection-inl-pre.h

@@ -15,11 +15,3 @@
  */
 
 #pragma once
-
-namespace apache {
-namespace thrift {
-
-namespace legacy_reflection_detail {}
-
-} // namespace thrift
-} // namespace apache

third-party/thrift/src/thrift/lib/cpp2/test/util/FakeClock.h

@@ -18,8 +18,7 @@
 
 #include <chrono>
 
-namespace apache {
-namespace thrift {
+namespace apache::thrift {
 
 class FakeClock {
  public:
@@ -42,5 +41,4 @@ class FakeClock {
   static time_point now_us_;
 };
 
-} // namespace thrift
-} // namespace apache
+} // namespace apache::thrift

third-party/thrift/src/thrift/lib/cpp2/transport/rocket/framing/FrameType.h

@@ -18,9 +18,7 @@
 
 #include <cstdint>
 
-namespace apache {
-namespace thrift {
-namespace rocket {
+namespace apache::thrift::rocket {
 
 // Commented-out values are not currently used/needed in Thrift, but may be
 // in the future.
@@ -51,6 +49,4 @@ enum class ExtFrameType : uint32_t {
   // CUSTOM_ALLOC = 0xFB3,
 };
 
-} // namespace rocket
-} // namespace thrift
-} // namespace apache
+} // namespace apache::thrift::rocket

third-party/thrift/src/thrift/lib/cpp2/transport/rocket/server/RocketServerHandler.h

@@ -17,8 +17,7 @@
 #pragma once
 #include <cstdint>
 
-namespace apache {
-namespace thrift {
+namespace apache::thrift {
 
 class Cpp2ConnContext;
 
@@ -72,5 +71,4 @@ class RocketServerHandler {
 };
 
 } // namespace rocket
-} // namespace thrift
-} // namespace apache
+} // namespace apache::thrift

third-party/thrift/src/thrift/lib/cpp2/type/Tag.h

@@ -27,9 +27,7 @@
 
 #include <cstdint>
 
-namespace apache {
-namespace thrift {
-namespace type {
+namespace apache::thrift::type {
 
 enum class FieldId : ::std::int16_t;
 
@@ -111,6 +109,4 @@ struct fields;
 template <typename Tag, typename Context>
 struct field : Tag {};
 
-} // namespace type
-} // namespace thrift
-} // namespace apache
+} // namespace apache::thrift::type

third-party/thrift/src/thrift/lib/cpp2/type/UniversalHashAlgorithm.h

@@ -18,15 +18,11 @@
 
 #include <cstdint>
 
-namespace apache {
-namespace thrift {
-namespace type {
+namespace apache::thrift::type {
 enum class UniversalHashAlgorithm {
   Sha2_256 = 2,
 };
 
 constexpr const int8_t kMinHashBytes = 8;
 constexpr const int8_t kDefaultHashBytes = 16;
-} // namespace type
-} // namespace thrift
-} // namespace apache
+} // namespace apache::thrift::type

third-party/thrift/src/thrift/lib/cpp2/util/Ewma.h

@@ -19,8 +19,7 @@
 #include <chrono>
 #include <cmath>
 
-namespace apache {
-namespace thrift {
+namespace apache::thrift {
 
 /**
  * Compute the EWMA (Exponential Weighted Moving Average) of a
@@ -77,5 +76,4 @@ class Ewma {
   std::chrono::time_point<Clock> timestamp_;
 };
 
-} // namespace thrift
-} // namespace apache
+} // namespace apache::thrift