chore: Enable clang-tidy modernize-use-nodiscard check (#7015)

Signed-off-by: Pratik Mankawde <3397372+pratikmankawde@users.noreply.github.com>
Co-authored-by: Ed Hennis <ed@ripple.com>

.clang-tidy

@@ -73,7 +73,7 @@ Checks: "-*,
   bugprone-unhandled-self-assignment,
   bugprone-unique-ptr-array-mismatch,
   bugprone-unsafe-functions,
-  bugprone-use-after-move, # has issues
+  bugprone-use-after-move,
   bugprone-unused-raii,
   bugprone-unused-return-value,
   bugprone-unused-local-non-trivial-variable,
@@ -106,6 +106,7 @@ Checks: "-*,
   modernize-use-emplace,
   modernize-use-equals-default,
   modernize-use-equals-delete,
+  modernize-use-nodiscard,
   modernize-use-override,
   modernize-use-ranges,
   modernize-use-starts-ends-with,

cmake/XrplCompiler.cmake

@@ -118,7 +118,7 @@ if(MSVC)
             NOMINMAX
             # TODO: Resolve these warnings, don't just silence them
             _SILENCE_ALL_CXX17_DEPRECATION_WARNINGS
-            $<$<AND:$<COMPILE_LANGUAGE:CXX>,$<CONFIG:Debug>,$<NOT:$<BOOL:${is_ci}>>>:_CRTDBG_MAP_ALLOC>
+            $<$<AND:$<COMPILE_LANGUAGE:CXX>,$<CONFIG:Debug>>:_CRTDBG_MAP_ALLOC>
     )
     target_link_libraries(common INTERFACE -errorreport:none -machine:X64)
 else()

include/xrpl/basics/BasicConfig.h

@@ -36,7 +36,7 @@ public:
     explicit Section(std::string name = "");
 
     /** Returns the name of this section. */
-    std::string const&
+    [[nodiscard]] std::string const&
     name() const
     {
         return name_;
@@ -45,7 +45,7 @@ public:
     /** Returns all the lines in the section.
         This includes everything.
     */
-    std::vector<std::string> const&
+    [[nodiscard]] std::vector<std::string> const&
     lines() const
     {
         return lines_;
@@ -54,7 +54,7 @@ public:
     /** Returns all the values in the section.
         Values are non-empty lines which are not key/value pairs.
     */
-    std::vector<std::string> const&
+    [[nodiscard]] std::vector<std::string> const&
     values() const
     {
         return values_;
@@ -82,7 +82,7 @@ public:
      * @return The retrieved value. A section with an empty legacy value returns
                an empty string.
      */
-    std::string
+    [[nodiscard]] std::string
     legacy() const
     {
         if (lines_.empty())
@@ -117,11 +117,11 @@ public:
     }
 
     /** Returns `true` if a key with the given name exists. */
-    bool
+    [[nodiscard]] bool
     exists(std::string const& name) const;
 
     template <class T = std::string>
-    std::optional<T>
+    [[nodiscard]] std::optional<T>
     get(std::string const& name) const
     {
         auto const iter = lookup_.find(name);
@@ -132,7 +132,7 @@ public:
 
     /// Returns a value if present, else another value.
     template <class T>
-    T
+    [[nodiscard]] T
     value_or(std::string const& name, T const& other) const
     {
         auto const v = get<T>(name);
@@ -141,7 +141,7 @@ public:
 
     // indicates if trailing comments were seen
     // during the appending of any lines/values
-    bool
+    [[nodiscard]] bool
     had_trailing_comments() const
     {
         return had_trailing_comments_;
@@ -151,42 +151,42 @@ public:
     operator<<(std::ostream&, Section const& section);
 
     // Returns `true` if there are no key/value pairs.
-    bool
+    [[nodiscard]] bool
     empty() const
     {
         return lookup_.empty();
     }
 
     // Returns the number of key/value pairs.
-    std::size_t
+    [[nodiscard]] std::size_t
     size() const
     {
         return lookup_.size();
     }
 
     // For iteration of key/value pairs.
-    const_iterator
+    [[nodiscard]] const_iterator
     begin() const
     {
         return lookup_.cbegin();
     }
 
     // For iteration of key/value pairs.
-    const_iterator
+    [[nodiscard]] const_iterator
     cbegin() const
     {
         return lookup_.cbegin();
     }
 
     // For iteration of key/value pairs.
-    const_iterator
+    [[nodiscard]] const_iterator
     end() const
     {
         return lookup_.cend();
     }
 
     // For iteration of key/value pairs.
-    const_iterator
+    [[nodiscard]] const_iterator
     cend() const
     {
         return lookup_.cend();
@@ -206,7 +206,7 @@ private:
 
 public:
     /** Returns `true` if a section with the given name exists. */
-    bool
+    [[nodiscard]] bool
     exists(std::string const& name) const;
 
     /** Returns the section with the given name.
@@ -216,7 +216,7 @@ public:
     Section&
     section(std::string const& name);
 
-    Section const&
+    [[nodiscard]] Section const&
     section(std::string const& name) const;
 
     Section const&
@@ -264,7 +264,7 @@ public:
      *         legacy value.
      *  @return Contents of the legacy value.
      */
-    std::string
+    [[nodiscard]] std::string
     legacy(std::string const& sectionName) const;
 
     friend std::ostream&
@@ -272,7 +272,7 @@ public:
 
     // indicates if trailing comments were seen
     // in any loaded Sections
-    bool
+    [[nodiscard]] bool
     had_trailing_comments() const
     {
         return std::ranges::any_of(map_, [](auto s) { return s.second.had_trailing_comments(); });

include/xrpl/basics/Buffer.h

@@ -101,13 +101,13 @@ public:
     }
 
     /** Returns the number of bytes in the buffer. */
-    std::size_t
+    [[nodiscard]] std::size_t
     size() const noexcept
     {
         return size_;
     }
 
-    bool
+    [[nodiscard]] bool
     empty() const noexcept
     {
         return 0 == size_;
@@ -125,7 +125,7 @@ public:
               to a single byte, to facilitate pointer arithmetic.
     */
     /** @{ */
-    std::uint8_t const*
+    [[nodiscard]] std::uint8_t const*
     data() const noexcept
     {
         return p_.get();
@@ -169,25 +169,25 @@ public:
         return alloc(n);
     }
 
-    const_iterator
+    [[nodiscard]] const_iterator
     begin() const noexcept
     {
         return p_.get();
     }
 
-    const_iterator
+    [[nodiscard]] const_iterator
     cbegin() const noexcept
     {
         return p_.get();
     }
 
-    const_iterator
+    [[nodiscard]] const_iterator
     end() const noexcept
     {
         return p_.get() + size_;
     }
 
-    const_iterator
+    [[nodiscard]] const_iterator
     cend() const noexcept
     {
         return p_.get() + size_;

include/xrpl/basics/CountedObject.h

@@ -19,7 +19,7 @@ public:
     using Entry = std::pair<std::string, int>;
     using List = std::vector<Entry>;
 
-    List
+    [[nodiscard]] List
     getCounts(int minimumThreshold) const;
 
 public:
@@ -59,19 +59,19 @@ public:
             return --count_;
         }
 
-        int
+        [[nodiscard]] int
         getCount() const noexcept
         {
             return count_.load();
         }
 
-        Counter*
+        [[nodiscard]] Counter*
         getNext() const noexcept
         {
             return next_;
         }
 
-        std::string const&
+        [[nodiscard]] std::string const&
         getName() const noexcept
         {
             return name_;

include/xrpl/basics/Expected.h

@@ -73,7 +73,7 @@ public:
     {
     }
 
-    constexpr E const&
+    [[nodiscard]] constexpr E const&
     value() const&
     {
         return val_;
@@ -91,7 +91,7 @@ public:
         return std::move(val_);
     }
 
-    constexpr E const&&
+    [[nodiscard]] constexpr E const&&
     value() const&&
     {
         return std::move(val_);
@@ -125,13 +125,13 @@ public:
     {
     }
 
-    constexpr bool
+    [[nodiscard]] constexpr bool
     has_value() const
     {
         return Base::has_value();
     }
 
-    constexpr T const&
+    [[nodiscard]] constexpr T const&
     value() const
     {
         return Base::value();
@@ -143,7 +143,7 @@ public:
         return Base::value();
     }
 
-    constexpr E const&
+    [[nodiscard]] constexpr E const&
     error() const
     {
         return Base::error();
@@ -210,7 +210,7 @@ public:
     {
     }
 
-    constexpr E const&
+    [[nodiscard]] constexpr E const&
     error() const
     {
         return Base::error();

include/xrpl/basics/IntrusivePointer.h

@@ -159,11 +159,11 @@ public:
     reset();
 
     /** Get the raw pointer */
-    T*
+    [[nodiscard]] T*
     get() const;
 
     /** Return the strong count */
-    std::size_t
+    [[nodiscard]] std::size_t
     use_count() const;
 
     template <class TT, class... Args>
@@ -181,7 +181,7 @@ public:
 
 private:
     /** Return the raw pointer held by this object. */
-    T*
+    [[nodiscard]] T*
     unsafeGetRawPtr() const;
 
     /** Exchange the current raw pointer held by this object with the given
@@ -260,7 +260,7 @@ public:
     lock() const;
 
     /** Return true if the strong count is zero. */
-    bool
+    [[nodiscard]] bool
     expired() const;
 
     /** Set the pointer to null and decrement the weak count.
@@ -339,7 +339,7 @@ public:
        don't lock the weak pointer. Use the `lock` method if that's what's
        needed)
      */
-    SharedIntrusive<T>
+    [[nodiscard]] SharedIntrusive<T>
     getStrong() const;
 
     /** Return true if this is a strong pointer and the strong pointer is
@@ -357,31 +357,31 @@ public:
     /** If this is a strong pointer, return the raw pointer. Otherwise
        return null.
      */
-    T*
+    [[nodiscard]] T*
     get() const;
 
     /** If this is a strong pointer, return the strong count. Otherwise
      * return 0
      */
-    std::size_t
+    [[nodiscard]] std::size_t
     use_count() const;
 
     /** Return true if there is a non-zero strong count. */
-    bool
+    [[nodiscard]] bool
     expired() const;
 
     /** If this is a strong pointer, return the strong pointer. Otherwise
         attempt to lock the weak pointer.
      */
-    SharedIntrusive<T>
+    [[nodiscard]] SharedIntrusive<T>
     lock() const;
 
     /** Return true is this represents a strong pointer. */
-    bool
+    [[nodiscard]] bool
     isStrong() const;
 
     /** Return true is this represents a weak pointer. */
-    bool
+    [[nodiscard]] bool
     isWeak() const;
 
     /** If this is a weak pointer, attempt to convert it to a strong
@@ -412,7 +412,7 @@ private:
 private:
     /** Return the raw pointer held by this object.
      */
-    T*
+    [[nodiscard]] T*
     unsafeGetRawPtr() const;
 
     enum class RefStrength { strong, weak };

include/xrpl/basics/IntrusiveRefCounts.h

@@ -207,7 +207,7 @@ private:
         RefCountPair(CountType s, CountType w) noexcept;
 
         /** Convert back to the packed integer form. */
-        FieldType
+        [[nodiscard]] FieldType
         combinedValue() const noexcept;
 
         static constexpr CountType maxStrongValue =

include/xrpl/basics/Log.h

@@ -76,7 +76,7 @@ private:
             @return `true` if a system file is associated and opened for
             writing.
         */
-        bool
+        [[nodiscard]] bool
         isOpen() const noexcept;
 
         /** Associate a system file with the log.

include/xrpl/basics/Mutex.hpp

@@ -44,7 +44,7 @@ public:
         return data_;
     }
 
-    ProtectedDataType const&
+    [[nodiscard]] ProtectedDataType const&
     get() const
     {
         return data_;

include/xrpl/basics/Number.h

@@ -252,9 +252,9 @@ public:
     // Assume unsigned values are... unsigned. i.e. positive
     explicit Number(internalrep mantissa, int exponent, normalized);
 
-    constexpr rep
+    [[nodiscard]] constexpr rep
     mantissa() const noexcept;
-    constexpr int
+    [[nodiscard]] constexpr int
     exponent() const noexcept;
 
     constexpr Number
@@ -339,7 +339,7 @@ public:
     }
 
     /** Return the sign of the amount */
-    constexpr int
+    [[nodiscard]] constexpr int
     signum() const noexcept
     {
         if (negative_)
@@ -347,7 +347,7 @@ public:
         return (mantissa_ != 0u) ? 1 : 0;
     }
 
-    Number
+    [[nodiscard]] Number
     truncate() const noexcept;
 
     friend constexpr bool
@@ -490,13 +490,13 @@ private:
         MantissaRange::rep const& minMantissa,
         MantissaRange::rep const& maxMantissa);
 
-    bool
+    [[nodiscard]] bool
     isnormal() const noexcept;
 
     // Copy the number, but modify the exponent by "exponentDelta". Because the
     // mantissa doesn't change, the result will be "mostly" normalized, but the
     // exponent could go out of range, so it will be checked.
-    Number
+    [[nodiscard]] Number
     shiftExponent(int exponentDelta) const;
 
     // Safely convert rep (int64) mantissa to internalrep (uint64). If the rep

include/xrpl/basics/SHAMapHash.h

@@ -20,7 +20,7 @@ public:
     {
     }
 
-    uint256 const&
+    [[nodiscard]] uint256 const&
     as_uint256() const
     {
         return hash_;
@@ -30,17 +30,17 @@ public:
     {
         return hash_;
     }
-    bool
+    [[nodiscard]] bool
     isZero() const
     {
         return hash_.isZero();
     }
-    bool
+    [[nodiscard]] bool
     isNonZero() const
     {
         return hash_.isNonZero();
     }
-    int
+    [[nodiscard]] int
     signum() const
     {
         return hash_.signum();

include/xrpl/basics/SharedWeakCachePointer.h

@@ -49,7 +49,7 @@ public:
     /** Return a strong pointer if this is already a strong pointer (i.e. don't
         lock the weak pointer. Use the `lock` method if that's what's needed)
      */
-    std::shared_ptr<T> const&
+    [[nodiscard]] std::shared_ptr<T> const&
     getStrong() const;
 
     /** Return true if this is a strong pointer and the strong pointer is
@@ -67,30 +67,30 @@ public:
     /** If this is a strong pointer, return the raw pointer. Otherwise return
         null.
      */
-    T*
+    [[nodiscard]] T*
     get() const;
 
     /** If this is a strong pointer, return the strong count. Otherwise return 0
      */
-    std::size_t
+    [[nodiscard]] std::size_t
     use_count() const;
 
     /** Return true if there is a non-zero strong count. */
-    bool
+    [[nodiscard]] bool
     expired() const;
 
     /** If this is a strong pointer, return the strong pointer. Otherwise
         attempt to lock the weak pointer.
      */
-    std::shared_ptr<T>
+    [[nodiscard]] std::shared_ptr<T>
     lock() const;
 
     /** Return true is this represents a strong pointer. */
-    bool
+    [[nodiscard]] bool
     isStrong() const;
 
     /** Return true is this represents a weak pointer. */
-    bool
+    [[nodiscard]] bool
     isWeak() const;
 
     /** If this is a weak pointer, attempt to convert it to a strong pointer.

include/xrpl/basics/SlabAllocator.h

@@ -180,7 +180,7 @@ public:
     ~SlabAllocator() = default;
 
     /** Returns the size of the memory block this allocator returns. */
-    constexpr std::size_t
+    [[nodiscard]] constexpr std::size_t
     size() const noexcept
     {
         return itemSize_;

include/xrpl/basics/Slice.h

@@ -74,7 +74,7 @@ public:
         @note The return type is guaranteed to be a pointer
               to a single byte, to facilitate pointer arithmetic.
     */
-    std::uint8_t const*
+    [[nodiscard]] std::uint8_t const*
     data() const noexcept
     {
         return data_;
@@ -123,25 +123,25 @@ public:
         size_ -= n;
     }
 
-    const_iterator
+    [[nodiscard]] const_iterator
     begin() const noexcept
     {
         return data_;
     }
 
-    const_iterator
+    [[nodiscard]] const_iterator
     cbegin() const noexcept
     {
         return data_;
     }
 
-    const_iterator
+    [[nodiscard]] const_iterator
     end() const noexcept
     {
         return data_ + size_;
     }
 
-    const_iterator
+    [[nodiscard]] const_iterator
     cend() const noexcept
     {
         return data_ + size_;
@@ -158,7 +158,7 @@ public:
         @returns The requested subslice, if the request is valid.
         @throws std::out_of_range if pos > size()
      */
-    Slice
+    [[nodiscard]] Slice
     substr(std::size_t pos, std::size_t count = std::numeric_limits<std::size_t>::max()) const
     {
         if (pos > size())

include/xrpl/basics/TaggedCache.h

@@ -222,19 +222,19 @@ private:
         {
         }
 
-        bool
+        [[nodiscard]] bool
         isWeak() const
         {
             if (!ptr)
                 return true;
             return ptr.isWeak();
         }
-        bool
+        [[nodiscard]] bool
         isCached() const
         {
             return ptr && ptr.isStrong();
         }
-        bool
+        [[nodiscard]] bool
         isExpired() const
         {
             return ptr.expired();

include/xrpl/basics/base_uint.h

@@ -102,7 +102,7 @@ public:
     {
         return reinterpret_cast<pointer>(data_.data());
     }
-    const_pointer
+    [[nodiscard]] const_pointer
     data() const
     {
         return reinterpret_cast<const_pointer>(data_.data());
@@ -118,22 +118,22 @@ public:
     {
         return data() + bytes;
     }
-    const_iterator
+    [[nodiscard]] const_iterator
     begin() const
     {
         return data();
     }
-    const_iterator
+    [[nodiscard]] const_iterator
     end() const
     {
         return data() + bytes;
     }
-    const_iterator
+    [[nodiscard]] const_iterator
     cbegin() const
     {
         return data();
     }
-    const_iterator
+    [[nodiscard]] const_iterator
     cend() const
     {
         return data() + bytes;
@@ -310,7 +310,7 @@ public:
         return fromVoid(from.data());
     }
 
-    constexpr int
+    [[nodiscard]] constexpr int
     signum() const
     {
         for (int i = 0; i < WIDTH; i++)
@@ -433,14 +433,14 @@ public:
         return ret;
     }
 
-    base_uint
+    [[nodiscard]] base_uint
     next() const
     {
         auto ret = *this;
         return ++ret;
     }
 
-    base_uint
+    [[nodiscard]] base_uint
     prev() const
     {
         auto ret = *this;
@@ -517,12 +517,12 @@ public:
     }
 
     // Deprecated.
-    bool
+    [[nodiscard]] bool
     isZero() const
     {
         return *this == beast::zero;
     }
-    bool
+    [[nodiscard]] bool
     isNonZero() const
     {
         return *this != beast::zero;

include/xrpl/beast/asio/io_latency_probe.h

@@ -49,7 +49,7 @@ public:
         return m_ios;
     }
 
-    boost::asio::io_context const&
+    [[nodiscard]] boost::asio::io_context const&
     get_io_context() const
     {
         return m_ios;

include/xrpl/beast/clock/abstract_clock.h

@@ -63,7 +63,7 @@ struct abstract_clock_wrapper : public abstract_clock<Facade>
     using typename abstract_clock<Facade>::duration;
     using typename abstract_clock<Facade>::time_point;
 
-    time_point
+    [[nodiscard]] time_point
     now() const override
     {
         return Clock::now();

include/xrpl/beast/clock/manual_clock.h

@@ -32,7 +32,7 @@ public:
     {
     }
 
-    time_point
+    [[nodiscard]] time_point
     now() const override
     {
         return now_;

include/xrpl/beast/container/detail/aged_container_iterator.h

@@ -115,7 +115,7 @@ public:
         return &m_iter->value;
     }
 
-    time_point const&
+    [[nodiscard]] time_point const&
     when() const
     {
         return m_iter->when;
@@ -136,7 +136,7 @@ private:
     {
     }
 
-    Iterator const&
+    [[nodiscard]] Iterator const&
     iterator() const
     {
         return m_iter;

include/xrpl/beast/container/detail/aged_ordered_container.h

@@ -186,7 +186,7 @@ private:
             return *this;
         }
 
-        Compare const&
+        [[nodiscard]] Compare const&
         compare() const
         {
             return *this;
@@ -295,7 +295,7 @@ private:
             return KeyValueCompare::compare();
         }
 
-        Compare const&
+        [[nodiscard]] Compare const&
         compare() const
         {
             return KeyValueCompare::compare();
@@ -307,7 +307,7 @@ private:
             return *this;
         }
 
-        KeyValueCompare const&
+        [[nodiscard]] KeyValueCompare const&
         key_compare() const
         {
             return *this;
@@ -319,7 +319,7 @@ private:
             return beast::detail::empty_base_optimization<ElementAllocator>::member();
         }
 
-        ElementAllocator const&
+        [[nodiscard]] ElementAllocator const&
         alloc() const
         {
             return beast::detail::empty_base_optimization<ElementAllocator>::member();

include/xrpl/beast/container/detail/aged_unordered_container.h

@@ -149,7 +149,7 @@ private:
             return *this;
         }
 
-        Hash const&
+        [[nodiscard]] Hash const&
         hash_function() const
         {
             return *this;
@@ -195,7 +195,7 @@ private:
             return *this;
         }
 
-        KeyEqual const&
+        [[nodiscard]] KeyEqual const&
         key_eq() const
         {
             return *this;
@@ -348,7 +348,7 @@ private:
             return *this;
         }
 
-        ValueHash const&
+        [[nodiscard]] ValueHash const&
         value_hash() const
         {
             return *this;
@@ -360,7 +360,7 @@ private:
             return ValueHash::hash_function();
         }
 
-        Hash const&
+        [[nodiscard]] Hash const&
         hash_function() const
         {
             return ValueHash::hash_function();
@@ -372,7 +372,7 @@ private:
             return *this;
         }
 
-        KeyValueEqual const&
+        [[nodiscard]] KeyValueEqual const&
         key_value_equal() const
         {
             return *this;
@@ -384,7 +384,7 @@ private:
             return key_value_equal().key_eq();
         }
 
-        KeyEqual const&
+        [[nodiscard]] KeyEqual const&
         key_eq() const
         {
             return key_value_equal().key_eq();
@@ -396,7 +396,7 @@ private:
             return beast::detail::empty_base_optimization<ElementAllocator>::member();
         }
 
-        ElementAllocator const&
+        [[nodiscard]] ElementAllocator const&
         alloc() const
         {
             return beast::detail::empty_base_optimization<ElementAllocator>::member();
@@ -433,7 +433,7 @@ private:
             m_vec.clear();
         }
 
-        size_type
+        [[nodiscard]] size_type
         max_bucket_count() const
         {
             return m_vec.max_size();
@@ -445,7 +445,7 @@ private:
             return m_max_load_factor;
         }
 
-        float const&
+        [[nodiscard]] float const&
         max_load_factor() const
         {
             return m_max_load_factor;

include/xrpl/beast/container/detail/empty_base_optimization.h

@@ -43,7 +43,7 @@ public:
         return *this;
     }
 
-    T const&
+    [[nodiscard]] T const&
     member() const noexcept
     {
         return *this;

include/xrpl/beast/core/List.h

@@ -128,7 +128,7 @@ public:
     }
 
 private:
-    reference
+    [[nodiscard]] reference
     dereference() const noexcept
     {
         return static_cast<reference>(*m_node);
@@ -287,14 +287,14 @@ public:
     /** Determine if the list is empty.
         @return `true` if the list is empty.
     */
-    bool
+    [[nodiscard]] bool
     empty() const noexcept
     {
         return size() == 0;
     }
 
     /** Returns the number of elements in the list. */
-    size_type
+    [[nodiscard]] size_type
     size() const noexcept
     {
         return m_size;
@@ -314,7 +314,7 @@ public:
         @invariant The list may not be empty.
         @return A const reference to the first element.
     */
-    const_reference
+    [[nodiscard]] const_reference
     front() const noexcept
     {
         return element_from(m_head.m_next);
@@ -334,7 +334,7 @@ public:
         @invariant The list may not be empty.
         @return A const reference to the last element.
     */
-    const_reference
+    [[nodiscard]] const_reference
     back() const noexcept
     {
         return element_from(m_tail.m_prev);
@@ -352,7 +352,7 @@ public:
     /** Obtain a const iterator to the beginning of the list.
         @return A const iterator pointing to the beginning of the list.
     */
-    const_iterator
+    [[nodiscard]] const_iterator
     begin() const noexcept
     {
         return const_iterator(m_head.m_next);
@@ -361,7 +361,7 @@ public:
     /** Obtain a const iterator to the beginning of the list.
         @return A const iterator pointing to the beginning of the list.
     */
-    const_iterator
+    [[nodiscard]] const_iterator
     cbegin() const noexcept
     {
         return const_iterator(m_head.m_next);
@@ -379,7 +379,7 @@ public:
     /** Obtain a const iterator to the end of the list.
         @return A constiterator pointing to the end of the list.
     */
-    const_iterator
+    [[nodiscard]] const_iterator
     end() const noexcept
     {
         return const_iterator(&m_tail);
@@ -388,7 +388,7 @@ public:
     /** Obtain a const iterator to the end of the list
         @return A constiterator pointing to the end of the list.
     */
-    const_iterator
+    [[nodiscard]] const_iterator
     cend() const noexcept
     {
         return const_iterator(&m_tail);
@@ -549,7 +549,7 @@ public:
         @param element The element to obtain an iterator for.
         @return A const iterator to the element.
     */
-    const_iterator
+    [[nodiscard]] const_iterator
     const_iterator_to(T const& element) const noexcept
     {
         return const_iterator(static_cast<Node const*>(&element));

include/xrpl/beast/core/LockFreeStack.h

@@ -162,7 +162,7 @@ public:
     operator=(LockFreeStack const&) = delete;
 
     /** Returns true if the stack is empty. */
-    bool
+    [[nodiscard]] bool
     empty() const
     {
         return m_head.load() == &m_end;
@@ -237,25 +237,25 @@ public:
         return iterator(&m_end);
     }
 
-    const_iterator
+    [[nodiscard]] const_iterator
     begin() const
     {
         return const_iterator(m_head.load());
     }
 
-    const_iterator
+    [[nodiscard]] const_iterator
     end() const
     {
         return const_iterator(&m_end);
     }
 
-    const_iterator
+    [[nodiscard]] const_iterator
     cbegin() const
     {
         return const_iterator(m_head.load());
     }
 
-    const_iterator
+    [[nodiscard]] const_iterator
     cend() const
     {
         return const_iterator(&m_end);

include/xrpl/beast/core/SemanticVersion.h

@@ -37,15 +37,15 @@ public:
     parse(std::string_view input);
 
     /** Produce a string from semantic version components. */
-    std::string
+    [[nodiscard]] std::string
     print() const;
 
-    bool
+    [[nodiscard]] bool
     isRelease() const noexcept
     {
         return preReleaseIdentifiers.empty();
     }
-    bool
+    [[nodiscard]] bool
     isPreRelease() const noexcept
     {
         return !isRelease();

include/xrpl/beast/insight/Event.h

@@ -45,7 +45,7 @@ public:
             m_impl->notify(ceil<value_type>(value));
     }
 
-    std::shared_ptr<EventImpl> const&
+    [[nodiscard]] std::shared_ptr<EventImpl> const&
     impl() const
     {
         return m_impl;

include/xrpl/beast/insight/Gauge.h

@@ -108,7 +108,7 @@ public:
     }
     /** @} */
 
-    std::shared_ptr<GaugeImpl> const&
+    [[nodiscard]] std::shared_ptr<GaugeImpl> const&
     impl() const
     {
         return m_impl;

include/xrpl/beast/insight/Group.h

@@ -14,7 +14,7 @@ public:
     using ptr = std::shared_ptr<Group>;
 
     /** Returns the name of this group, for diagnostics. */
-    virtual std::string const&
+    [[nodiscard]] virtual std::string const&
     name() const = 0;
 };
 

include/xrpl/beast/insight/Hook.h

@@ -24,7 +24,7 @@ public:
     {
     }
 
-    std::shared_ptr<HookImpl> const&
+    [[nodiscard]] std::shared_ptr<HookImpl> const&
     impl() const
     {
         return m_impl;

include/xrpl/beast/insight/Meter.h

@@ -63,7 +63,7 @@ public:
     }
     /** @} */
 
-    std::shared_ptr<MeterImpl> const&
+    [[nodiscard]] std::shared_ptr<MeterImpl> const&
     impl() const
     {
         return m_impl;

include/xrpl/beast/net/IPEndpoint.h

@@ -32,25 +32,25 @@ public:
     from_string(std::string const& s);
 
     /** Returns a string representing the endpoint. */
-    std::string
+    [[nodiscard]] std::string
     to_string() const;
 
     /** Returns the port number on the endpoint. */
-    Port
+    [[nodiscard]] Port
     port() const
     {
         return m_port;
     }
 
     /** Returns a new Endpoint with a different port. */
-    Endpoint
+    [[nodiscard]] Endpoint
     at_port(Port port) const
     {
         return Endpoint(m_addr, port);
     }
 
     /** Returns the address portion of this endpoint. */
-    Address const&
+    [[nodiscard]] Address const&
     address() const
     {
         return m_addr;
@@ -58,22 +58,22 @@ public:
 
     /** Convenience accessors for the address part. */
     /** @{ */
-    bool
+    [[nodiscard]] bool
     is_v4() const
     {
         return m_addr.is_v4();
     }
-    bool
+    [[nodiscard]] bool
     is_v6() const
     {
         return m_addr.is_v6();
     }
-    AddressV4
+    [[nodiscard]] AddressV4
     to_v4() const
     {
         return m_addr.to_v4();
     }
-    AddressV6
+    [[nodiscard]] AddressV6
     to_v6() const
     {
         return m_addr.to_v6();

include/xrpl/beast/unit_test/detail/const_container.h

@@ -25,7 +25,7 @@ protected:
         return m_cont;
     }
 
-    cont_type const&
+    [[nodiscard]] cont_type const&
     cont() const
     {
         return m_cont;
@@ -39,14 +39,14 @@ public:
     using const_iterator = typename cont_type::const_iterator;
 
     /** Returns `true` if the container is empty. */
-    bool
+    [[nodiscard]] bool
     empty() const
     {
         return m_cont.empty();
     }
 
     /** Returns the number of items in the container. */
-    size_type
+    [[nodiscard]] size_type
     size() const
     {
         return m_cont.size();
@@ -54,25 +54,25 @@ public:
 
     /** Returns forward iterators for traversal. */
     /** @{ */
-    const_iterator
+    [[nodiscard]] const_iterator
     begin() const
     {
         return m_cont.cbegin();
     }
 
-    const_iterator
+    [[nodiscard]] const_iterator
     cbegin() const
     {
         return m_cont.cbegin();
     }
 
-    const_iterator
+    [[nodiscard]] const_iterator
     end() const
     {
         return m_cont.cend();
     }
 
-    const_iterator
+    [[nodiscard]] const_iterator
     cend() const
     {
         return m_cont.cend();

include/xrpl/beast/unit_test/recorder.h

@@ -21,7 +21,7 @@ public:
     recorder() = default;
 
     /** Returns a report with the results of all completed suites. */
-    results const&
+    [[nodiscard]] results const&
     report() const
     {
         return m_results;

include/xrpl/beast/unit_test/results.h

@@ -41,14 +41,14 @@ private:
         tests_t() = default;
 
         /** Returns the total number of test conditions. */
-        std::size_t
+        [[nodiscard]] std::size_t
         total() const
         {
             return cont().size();
         }
 
         /** Returns the number of failed test conditions. */
-        std::size_t
+        [[nodiscard]] std::size_t
         failed() const
         {
             return failed_;
@@ -89,7 +89,7 @@ public:
     }
 
     /** Returns the name of this testcase. */
-    std::string const&
+    [[nodiscard]] std::string const&
     name() const
     {
         return name_;
@@ -118,21 +118,21 @@ public:
     }
 
     /** Returns the name of this suite. */
-    std::string const&
+    [[nodiscard]] std::string const&
     name() const
     {
         return name_;
     }
 
     /** Returns the total number of test conditions. */
-    std::size_t
+    [[nodiscard]] std::size_t
     total() const
     {
         return total_;
     }
 
     /** Returns the number of failures. */
-    std::size_t
+    [[nodiscard]] std::size_t
     failed() const
     {
         return failed_;
@@ -173,21 +173,21 @@ public:
     results() = default;
 
     /** Returns the total number of test cases. */
-    std::size_t
+    [[nodiscard]] std::size_t
     cases() const
     {
         return m_cases;
     }
 
     /** Returns the total number of test conditions. */
-    std::size_t
+    [[nodiscard]] std::size_t
     total() const
     {
         return total_;
     }
 
     /** Returns the number of failures. */
-    std::size_t
+    [[nodiscard]] std::size_t
     failed() const
     {
         return failed_;

include/xrpl/beast/unit_test/runner.h

@@ -47,7 +47,7 @@ public:
     }
 
     /** Returns the argument string. */
-    std::string const&
+    [[nodiscard]] std::string const&
     arg() const
     {
         return arg_;

include/xrpl/beast/unit_test/suite.h

@@ -57,7 +57,7 @@ private:
     // in the event of a failure, if the option to stop is set.
     struct abort_exception : public std::exception
     {
-        char const*
+        [[nodiscard]] char const*
         what() const noexcept override
         {
             return "test suite aborted";

include/xrpl/beast/unit_test/suite_info.h

@@ -42,33 +42,33 @@ public:
     {
     }
 
-    std::string const&
+    [[nodiscard]] std::string const&
     name() const
     {
         return name_;
     }
 
-    std::string const&
+    [[nodiscard]] std::string const&
     module() const
     {
         return module_;
     }
 
-    std::string const&
+    [[nodiscard]] std::string const&
     library() const
     {
         return library_;
     }
 
     /// Returns `true` if this suite only runs manually.
-    bool
+    [[nodiscard]] bool
     manual() const
     {
         return manual_;
     }
 
     /// Return the canonical suite name as a string.
-    std::string
+    [[nodiscard]] std::string
     full_name() const
     {
         return library_ + "." + module_ + "." + name_;

include/xrpl/beast/unit_test/thread.h

@@ -47,13 +47,13 @@ public:
         t_ = std::thread(&Thread::run, this, std::move(b));
     }
 
-    bool
+    [[nodiscard]] bool
     joinable() const
     {
         return t_.joinable();
     }
 
-    std::thread::id
+    [[nodiscard]] std::thread::id
     get_id() const
     {
         return t_.get_id();

include/xrpl/beast/utility/Journal.h

@@ -66,12 +66,12 @@ public:
         operator=(Sink const& lhs) = delete;
 
         /** Returns `true` if text at the passed severity produces output. */
-        virtual bool
+        [[nodiscard]] virtual bool
         active(Severity level) const;
 
         /** Returns `true` if a message is also written to the Output Window
          * (MSVC). */
-        virtual bool
+        [[nodiscard]] virtual bool
         console() const;
 
         /** Set whether messages are also written to the Output Window (MSVC).
@@ -80,7 +80,7 @@ public:
         console(bool output);
 
         /** Returns the minimum severity level this sink will report. */
-        virtual Severity
+        [[nodiscard]] virtual Severity
         threshold() const;
 
         /** Set the minimum severity this sink will report. */
@@ -204,14 +204,14 @@ public:
         operator=(Stream const& other) = delete;
 
         /** Returns the Sink that this Stream writes to. */
-        Sink&
+        [[nodiscard]] Sink&
         sink() const
         {
             return m_sink;
         }
 
         /** Returns the Severity level of messages this Stream reports. */
-        Severity
+        [[nodiscard]] Severity
         level() const
         {
             return m_level;
@@ -219,7 +219,7 @@ public:
 
         /** Returns `true` if sink logs anything at this stream's level. */
         /** @{ */
-        bool
+        [[nodiscard]] bool
         active() const
         {
             return m_sink.active(m_level);
@@ -267,14 +267,14 @@ public:
     }
 
     /** Returns the Sink associated with this Journal. */
-    Sink&
+    [[nodiscard]] Sink&
     sink() const
     {
         return *m_sink;
     }
 
     /** Returns a stream for this sink, with the specified severity level. */
-    Stream
+    [[nodiscard]] Stream
     stream(Severity level) const
     {
         return Stream(*m_sink, level);
@@ -284,7 +284,7 @@ public:
         For a message to be logged, the severity must be at or above the
         sink's severity threshold.
     */
-    bool
+    [[nodiscard]] bool
     active(Severity level) const
     {
         return m_sink->active(level);
@@ -292,37 +292,37 @@ public:
 
     /** Severity stream access functions. */
     /** @{ */
-    Stream
+    [[nodiscard]] Stream
     trace() const
     {
         return {*m_sink, severities::kTrace};
     }
 
-    Stream
+    [[nodiscard]] Stream
     debug() const
     {
         return {*m_sink, severities::kDebug};
     }
 
-    Stream
+    [[nodiscard]] Stream
     info() const
     {
         return {*m_sink, severities::kInfo};
     }
 
-    Stream
+    [[nodiscard]] Stream
     warn() const
     {
         return {*m_sink, severities::kWarning};
     }
 
-    Stream
+    [[nodiscard]] Stream
     error() const
     {
         return {*m_sink, severities::kError};
     }
 
-    Stream
+    [[nodiscard]] Stream
     fatal() const
     {
         return {*m_sink, severities::kFatal};

include/xrpl/beast/utility/PropertyStream.h

@@ -149,7 +149,7 @@ class PropertyStream::Item : public List<Item>::Node
 {
 public:
     explicit Item(Source* source);
-    Source&
+    [[nodiscard]] Source&
     source() const;
     Source*
     operator->() const;
@@ -217,7 +217,7 @@ public:
 
     PropertyStream&
     stream();
-    PropertyStream const&
+    [[nodiscard]] PropertyStream const&
     stream() const;
 
     template <typename Value>
@@ -287,7 +287,7 @@ public:
 
     PropertyStream&
     stream();
-    PropertyStream const&
+    [[nodiscard]] PropertyStream const&
     stream() const;
 
     template <typename Value>
@@ -323,7 +323,7 @@ public:
     operator=(Source const&) = delete;
 
     /** Returns the name of this source. */
-    std::string const&
+    [[nodiscard]] std::string const&
     name() const;
 
     /** Add a child source. */

include/xrpl/beast/utility/WrappedSink.h

@@ -35,13 +35,13 @@ public:
         prefix_ = s;
     }
 
-    bool
+    [[nodiscard]] bool
     active(beast::severities::Severity level) const override
     {
         return sink_.active(level);
     }
 
-    bool
+    [[nodiscard]] bool
     console() const override
     {
         return sink_.console();
@@ -53,7 +53,7 @@ public:
         sink_.console(output);
     }
 
-    beast::severities::Severity
+    [[nodiscard]] beast::severities::Severity
     threshold() const override
     {
         return sink_.threshold();

include/xrpl/beast/utility/temp_dir.h

@@ -43,7 +43,7 @@ public:
     }
 
     /// Get the native path for the temporary directory
-    std::string
+    [[nodiscard]] std::string
     path() const
     {
         return path_.string();
@@ -53,7 +53,7 @@ public:
 
         The file does not need to exist.
     */
-    std::string
+    [[nodiscard]] std::string
     file(std::string const& name) const
     {
         return (path_ / name).string();

include/xrpl/conditions/Fulfillment.h

@@ -41,15 +41,15 @@ public:
         with respect to other conditions of the
         same type.
    */
-    virtual Buffer
+    [[nodiscard]] virtual Buffer
     fingerprint() const = 0;
 
     /** Returns the type of this condition. */
-    virtual Type
+    [[nodiscard]] virtual Type
     type() const = 0;
 
     /** Validates a fulfillment. */
-    virtual bool
+    [[nodiscard]] virtual bool
     validate(Slice data) const = 0;
 
     /** Calculates the cost associated with this fulfillment. *
@@ -58,7 +58,7 @@ public:
         type and properties of the condition and the fulfillment
         that the condition is generated from.
     */
-    virtual std::uint32_t
+    [[nodiscard]] virtual std::uint32_t
     cost() const = 0;
 
     /** Returns the condition associated with the given fulfillment.
@@ -67,7 +67,7 @@ public:
         will, if compliant, produce the identical condition for the
         same fulfillment.
     */
-    virtual Condition
+    [[nodiscard]] virtual Condition
     condition() const = 0;
 };
 

include/xrpl/conditions/detail/PreimageSha256.h

@@ -90,13 +90,13 @@ public:
     {
     }
 
-    Type
+    [[nodiscard]] Type
     type() const override
     {
         return Type::preimageSha256;
     }
 
-    Buffer
+    [[nodiscard]] Buffer
     fingerprint() const override
     {
         sha256_hasher h;
@@ -105,19 +105,19 @@ public:
         return {d.data(), d.size()};
     }
 
-    std::uint32_t
+    [[nodiscard]] std::uint32_t
     cost() const override
     {
         return static_cast<std::uint32_t>(payload_.size());
     }
 
-    Condition
+    [[nodiscard]] Condition
     condition() const override
     {
         return {type(), cost(), fingerprint()};
     }
 
-    bool
+    [[nodiscard]] bool
     validate(Slice) const override
     {
         // Perhaps counterintuitively, the message isn't

include/xrpl/core/HashRouter.h

@@ -118,7 +118,7 @@ private:
                 peers_.insert(peer);
         }
 
-        HashRouterFlags
+        [[nodiscard]] HashRouterFlags
         getFlags(void) const
         {
             return flags_;
@@ -138,7 +138,7 @@ private:
         }
 
         /** Return seated relay time point if the message has been relayed */
-        std::optional<Stopwatch::time_point>
+        [[nodiscard]] std::optional<Stopwatch::time_point>
         relayed() const
         {
             return relayed_;

include/xrpl/core/Job.h

@@ -98,11 +98,11 @@ public:
         LoadMonitor& lm,
         std::function<void()> const& job);
 
-    JobType
+    [[nodiscard]] JobType
     getType() const;
 
     /** Returns the time when the job was queued. */
-    clock_type::time_point const&
+    [[nodiscard]] clock_type::time_point const&
     queue_time() const;
 
     void

include/xrpl/core/JobQueue.h

@@ -7,8 +7,13 @@
 #include <xrpl/core/detail/Workers.h>
 #include <xrpl/json/json_value.h>
 
+// Include only the specific Boost.Coroutine2 headers actually used here.
+// Avoid `boost/coroutine2/all.hpp` because it transitively pulls in
+// `boost/context/pooled_fixedsize_stack.hpp`, whose `.malloc()` / `.free()`
+// member calls on `boost::pool` collide with MSVC's `_CRTDBG_MAP_ALLOC` macros
+// in Debug builds (see cmake/XrplCompiler.cmake).
 #include <boost/context/protected_fixedsize_stack.hpp>
-#include <boost/coroutine2/all.hpp>
+#include <boost/coroutine2/coroutine.hpp>
 
 #include <set>
 

include/xrpl/core/JobTypeData.h

@@ -54,13 +54,13 @@ public:
     JobTypeData&
     operator=(JobTypeData const& other) = delete;
 
-    std::string
+    [[nodiscard]] std::string
     name() const
     {
         return info.name();
     }
 
-    JobType
+    [[nodiscard]] JobType
     type() const
     {
         return info.type();

include/xrpl/core/JobTypeInfo.h

@@ -40,37 +40,37 @@ public:
     {
     }
 
-    JobType
+    [[nodiscard]] JobType
     type() const
     {
         return m_type;
     }
 
-    std::string const&
+    [[nodiscard]] std::string const&
     name() const
     {
         return m_name;
     }
 
-    int
+    [[nodiscard]] int
     limit() const
     {
         return m_limit;
     }
 
-    bool
+    [[nodiscard]] bool
     special() const
     {
         return m_limit == 0;
     }
 
-    std::chrono::milliseconds
+    [[nodiscard]] std::chrono::milliseconds
     getAverageLatency() const
     {
         return m_avgLatency;
     }
 
-    std::chrono::milliseconds
+    [[nodiscard]] std::chrono::milliseconds
     getPeakLatency() const
     {
         return m_peakLatency;

include/xrpl/core/JobTypes.h

@@ -113,7 +113,7 @@ public:
         return instance().get(jt).name();
     }
 
-    JobTypeInfo const&
+    [[nodiscard]] JobTypeInfo const&
     get(JobType jt) const
     {
         Map::const_iterator const iter(m_map.find(jt));
@@ -125,37 +125,37 @@ public:
         return m_unknown;
     }
 
-    JobTypeInfo const&
+    [[nodiscard]] JobTypeInfo const&
     getInvalid() const
     {
         return m_unknown;
     }
 
-    Map::size_type
+    [[nodiscard]] Map::size_type
     size() const
     {
         return m_map.size();
     }
 
-    const_iterator
+    [[nodiscard]] const_iterator
     begin() const
     {
         return m_map.cbegin();
     }
 
-    const_iterator
+    [[nodiscard]] const_iterator
     cbegin() const
     {
         return m_map.cbegin();
     }
 
-    const_iterator
+    [[nodiscard]] const_iterator
     end() const
     {
         return m_map.cend();
     }
 
-    const_iterator
+    [[nodiscard]] const_iterator
     cend() const
     {
         return m_map.cend();

include/xrpl/core/LoadEvent.h

@@ -21,15 +21,15 @@ public:
 
     ~LoadEvent();
 
-    std::string const&
+    [[nodiscard]] std::string const&
     name() const;
 
     // The time spent waiting.
-    std::chrono::steady_clock::duration
+    [[nodiscard]] std::chrono::steady_clock::duration
     waitTime() const;
 
     // The time spent running.
-    std::chrono::steady_clock::duration
+    [[nodiscard]] std::chrono::steady_clock::duration
     runTime() const;
 
     void

include/xrpl/core/NetworkIDService.h

@@ -26,7 +26,7 @@ public:
      *
      * @return The network ID this server is configured for
      */
-    virtual std::uint32_t
+    [[nodiscard]] virtual std::uint32_t
     getNetworkID() const noexcept = 0;
 };
 

include/xrpl/core/PeerReservationTable.h

@@ -22,7 +22,7 @@ public:
     PublicKey nodeId;
     std::string description = {};  // NOLINT(readability-redundant-member-init)
 
-    auto
+    [[nodiscard]] auto
     toJson() const -> Json::Value;
 
     template <typename Hasher>

include/xrpl/core/PerfLog.h

@@ -121,7 +121,7 @@ public:
      *
      * @return Counters Json object
      */
-    virtual Json::Value
+    [[nodiscard]] virtual Json::Value
     countersJson() const = 0;
 
     /**
@@ -129,7 +129,7 @@ public:
      *
      * @return Current executing jobs and RPC calls and durations
      */
-    virtual Json::Value
+    [[nodiscard]] virtual Json::Value
     currentJson() const = 0;
 
     /**

include/xrpl/core/ServiceRegistry.h

@@ -192,7 +192,7 @@ public:
     virtual OpenLedger&
     getOpenLedger() = 0;
 
-    virtual OpenLedger const&
+    [[nodiscard]] virtual OpenLedger const&
     getOpenLedger() const = 0;
 
     // Transaction and operation services
@@ -219,7 +219,7 @@ public:
     getPerfLog() = 0;
 
     // Configuration and state
-    virtual bool
+    [[nodiscard]] virtual bool
     isStopping() const = 0;
 
     virtual beast::Journal
@@ -231,7 +231,7 @@ public:
     virtual Logs&
     getLogs() = 0;
 
-    virtual std::optional<uint256> const&
+    [[nodiscard]] virtual std::optional<uint256> const&
     getTrapTxID() const = 0;
 
     /** Retrieve the "wallet database" */

include/xrpl/core/detail/Workers.h

@@ -106,7 +106,7 @@ public:
 
         @note This function is not thread-safe.
     */
-    int
+    [[nodiscard]] int
     getNumberOfThreads() const noexcept;
 
     /** Set the desired number of threads.
@@ -141,7 +141,7 @@ public:
         While this function is thread-safe, the value may not stay
         accurate for very long. It's mainly for diagnostic purposes.
     */
-    int
+    [[nodiscard]] int
     numberOfCurrentlyRunningTasks() const noexcept;
 
     //--------------------------------------------------------------------------

include/xrpl/json/JsonPropertyStream.h

@@ -14,7 +14,7 @@ public:
 
 public:
     JsonPropertyStream();
-    Json::Value const&
+    [[nodiscard]] Json::Value const&
     top() const;
 
 protected:

include/xrpl/json/json_reader.h

@@ -64,7 +64,7 @@ public:
      * their location in the parsed document. An empty string is returned if no
      * error occurred during parsing.
      */
-    std::string
+    [[nodiscard]] std::string
     getFormattedErrorMessages() const;
 
     static constexpr unsigned nest_limit{25};

include/xrpl/json/json_value.h

@@ -53,7 +53,7 @@ public:
         return str_;
     }
 
-    constexpr char const*
+    [[nodiscard]] constexpr char const*
     c_str() const
     {
         return str_;
@@ -158,11 +158,11 @@ private:
         operator<(CZString const& other) const;
         bool
         operator==(CZString const& other) const;
-        int
+        [[nodiscard]] int
         index() const;
-        char const*
+        [[nodiscard]] char const*
         c_str() const;
-        bool
+        [[nodiscard]] bool
         isStaticString() const;
 
     private:
@@ -223,60 +223,60 @@ public:
     void
     swap(Value& other) noexcept;
 
-    ValueType
+    [[nodiscard]] ValueType
     type() const;
 
-    char const*
+    [[nodiscard]] char const*
     asCString() const;
     /** Returns the unquoted string value. */
-    std::string
+    [[nodiscard]] std::string
     asString() const;
-    Int
+    [[nodiscard]] Int
     asInt() const;
-    UInt
+    [[nodiscard]] UInt
     asUInt() const;
-    double
+    [[nodiscard]] double
     asDouble() const;
-    bool
+    [[nodiscard]] bool
     asBool() const;
 
     /** Correct absolute value from int or unsigned int */
-    UInt
+    [[nodiscard]] UInt
     asAbsUInt() const;
 
     // TODO: What is the "empty()" method this docstring mentions?
     /** isNull() tests to see if this field is null.  Don't use this method to
         test for emptiness: use empty(). */
-    bool
+    [[nodiscard]] bool
     isNull() const;
-    bool
+    [[nodiscard]] bool
     isBool() const;
-    bool
+    [[nodiscard]] bool
     isInt() const;
-    bool
+    [[nodiscard]] bool
     isUInt() const;
-    bool
+    [[nodiscard]] bool
     isIntegral() const;
-    bool
+    [[nodiscard]] bool
     isDouble() const;
-    bool
+    [[nodiscard]] bool
     isNumeric() const;
-    bool
+    [[nodiscard]] bool
     isString() const;
-    bool
+    [[nodiscard]] bool
     isArray() const;
-    bool
+    [[nodiscard]] bool
     isArrayOrNull() const;
-    bool
+    [[nodiscard]] bool
     isObject() const;
-    bool
+    [[nodiscard]] bool
     isObjectOrNull() const;
 
-    bool
+    [[nodiscard]] bool
     isConvertibleTo(ValueType other) const;
 
     /// Number of values in array or object
-    UInt
+    [[nodiscard]] UInt
     size() const;
 
     /** Returns false if this is an empty array, empty object, empty string,
@@ -304,10 +304,10 @@ public:
     operator[](UInt index) const;
     /// If the array contains at least index+1 elements, returns the element
     /// value, otherwise returns defaultValue.
-    Value
+    [[nodiscard]] Value
     get(UInt index, Value const& defaultValue) const;
     /// Return true if index < size().
-    bool
+    [[nodiscard]] bool
     isValidIndex(UInt index) const;
     /// \brief Append value to array at the end.
     ///
@@ -355,7 +355,7 @@ public:
     Value
     get(char const* key, Value const& defaultValue) const;
     /// Return the member named key if it exist, defaultValue otherwise.
-    Value
+    [[nodiscard]] Value
     get(std::string const& key, Value const& defaultValue) const;
 
     /// \brief Remove and return the named member.
@@ -374,10 +374,10 @@ public:
     bool
     isMember(char const* key) const;
     /// Return true if the object has a member named key.
-    bool
+    [[nodiscard]] bool
     isMember(std::string const& key) const;
     /// Return true if the object has a member named key.
-    bool
+    [[nodiscard]] bool
     isMember(StaticString const& key) const;
 
     /// \brief Return a list of the member names.
@@ -385,15 +385,15 @@ public:
     /// If null, return an empty list.
     /// \pre type() is objectValue or nullValue
     /// \post if type() was nullValue, it remains nullValue
-    Members
+    [[nodiscard]] Members
     getMemberNames() const;
 
-    std::string
+    [[nodiscard]] std::string
     toStyledString() const;
 
-    const_iterator
+    [[nodiscard]] const_iterator
     begin() const;
-    const_iterator
+    [[nodiscard]] const_iterator
     end() const;
 
     iterator
@@ -513,20 +513,20 @@ public:
 
     /// Return either the index or the member name of the referenced value as a
     /// Value.
-    Value
+    [[nodiscard]] Value
     key() const;
 
     /// Return the index of the referenced Value. -1 if it is not an arrayValue.
-    UInt
+    [[nodiscard]] UInt
     index() const;
 
     /// Return the member name of the referenced Value. "" if it is not an
     /// objectValue.
-    char const*
+    [[nodiscard]] char const*
     memberName() const;
 
 protected:
-    Value&
+    [[nodiscard]] Value&
     deref() const;
 
     void
@@ -535,10 +535,10 @@ protected:
     void
     decrement();
 
-    difference_type
+    [[nodiscard]] difference_type
     computeDistance(SelfType const& other) const;
 
-    bool
+    [[nodiscard]] bool
     isEqual(SelfType const& other) const;
 
     void

include/xrpl/ledger/AcceptedLedgerTx.h

@@ -30,47 +30,47 @@ public:
         std::shared_ptr<STTx const> const&,
         std::shared_ptr<STObject const> const&);
 
-    std::shared_ptr<STTx const> const&
+    [[nodiscard]] std::shared_ptr<STTx const> const&
     getTxn() const
     {
         return mTxn;
     }
-    TxMeta const&
+    [[nodiscard]] TxMeta const&
     getMeta() const
     {
         return mMeta;
     }
 
-    boost::container::flat_set<AccountID> const&
+    [[nodiscard]] boost::container::flat_set<AccountID> const&
     getAffected() const
     {
         return mAffected;
     }
 
-    TxID
+    [[nodiscard]] TxID
     getTransactionID() const
     {
         return mTxn->getTransactionID();
     }
-    TxType
+    [[nodiscard]] TxType
     getTxnType() const
     {
         return mTxn->getTxnType();
     }
-    TER
+    [[nodiscard]] TER
     getResult() const
     {
         return mMeta.getResultTER();
     }
-    std::uint32_t
+    [[nodiscard]] std::uint32_t
     getTxnSeq() const
     {
         return mMeta.getIndex();
     }
-    std::string
+    [[nodiscard]] std::string
     getEscMeta() const;
 
-    Json::Value const&
+    [[nodiscard]] Json::Value const&
     getJson() const
     {
         return mJson;

include/xrpl/ledger/AmendmentTable.h

@@ -36,7 +36,7 @@ public:
 
     virtual ~AmendmentTable() = default;
 
-    virtual uint256
+    [[nodiscard]] virtual uint256
     find(std::string const& name) const = 0;
 
     virtual bool
@@ -47,9 +47,9 @@ public:
     virtual bool
     enable(uint256 const& amendment) = 0;
 
-    virtual bool
+    [[nodiscard]] virtual bool
     isEnabled(uint256 const& amendment) const = 0;
-    virtual bool
+    [[nodiscard]] virtual bool
     isSupported(uint256 const& amendment) const = 0;
 
     /**
@@ -58,17 +58,17 @@ public:
      *
      * @return true if an unsupported feature is enabled on the network
      */
-    virtual bool
+    [[nodiscard]] virtual bool
     hasUnsupportedEnabled() const = 0;
 
-    virtual std::optional<NetClock::time_point>
+    [[nodiscard]] virtual std::optional<NetClock::time_point>
     firstUnsupportedExpected() const = 0;
 
-    virtual Json::Value
+    [[nodiscard]] virtual Json::Value
     getJson(bool isAdmin) const = 0;
 
     /** Returns a Json::objectValue. */
-    virtual Json::Value
+    [[nodiscard]] virtual Json::Value
     getJson(uint256 const& amendment, bool isAdmin) const = 0;
 
     /** Called when a new fully-validated ledger is accepted. */
@@ -87,7 +87,7 @@ public:
     /** Called to determine whether the amendment logic needs to process
         a new validated ledger. (If it could have changed things.)
     */
-    virtual bool
+    [[nodiscard]] virtual bool
     needValidatedLedger(LedgerIndex seq) const = 0;
 
     virtual void
@@ -112,14 +112,14 @@ public:
 
     // Called by the consensus code when we need to
     // add feature entries to a validation
-    virtual std::vector<uint256>
+    [[nodiscard]] virtual std::vector<uint256>
     doValidation(std::set<uint256> const& enabled) const = 0;
 
     // The set of amendments to enable in the genesis ledger
     // This will return all known, non-vetoed amendments.
     // If we ever have two amendments that should not both be
     // enabled at the same time, we should ensure one is vetoed.
-    virtual std::vector<uint256>
+    [[nodiscard]] virtual std::vector<uint256>
     getDesired() const = 0;
 
     // The function below adapts the API callers expect to the

include/xrpl/ledger/ApplyView.h

@@ -134,7 +134,7 @@ public:
         while transactions applied to the consensus
         ledger produce hard failures (and claim a fee).
     */
-    virtual ApplyFlags
+    [[nodiscard]] virtual ApplyFlags
     flags() const = 0;
 
     /** Prepare to modify the SLE associated with key.

include/xrpl/ledger/BookDirs.h

@@ -22,10 +22,10 @@ public:
 
     BookDirs(ReadView const&, Book const&);
 
-    const_iterator
+    [[nodiscard]] const_iterator
     begin() const;
 
-    const_iterator
+    [[nodiscard]] const_iterator
     end() const;
 };
 

include/xrpl/ledger/CanonicalTXSet.h

@@ -59,13 +59,13 @@ private:
             return !(lhs == rhs);
         }
 
-        uint256 const&
+        [[nodiscard]] uint256 const&
         getAccount() const
         {
             return account_;
         }
 
-        uint256 const&
+        [[nodiscard]] uint256 const&
         getTXID() const
         {
             return txId_;
@@ -118,30 +118,30 @@ public:
         return map_.erase(it);
     }
 
-    const_iterator
+    [[nodiscard]] const_iterator
     begin() const
     {
         return map_.begin();
     }
 
-    const_iterator
+    [[nodiscard]] const_iterator
     end() const
     {
         return map_.end();
     }
 
-    size_t
+    [[nodiscard]] size_t
     size() const
     {
         return map_.size();
     }
-    bool
+    [[nodiscard]] bool
     empty() const
     {
         return map_.empty();
     }
 
-    uint256 const&
+    [[nodiscard]] uint256 const&
     key() const
     {
         return salt_;

include/xrpl/ledger/Dir.h

@@ -31,10 +31,10 @@ public:
 
     Dir(ReadView const&, Keylet const&);
 
-    const_iterator
+    [[nodiscard]] const_iterator
     begin() const;
 
-    const_iterator
+    [[nodiscard]] const_iterator
     end() const;
 };
 

include/xrpl/ledger/PaymentSandbox.h

@@ -74,10 +74,10 @@ public:
 
     // Get the adjustments for the balance between main and other.
     // Returns the debits, credits and the original balance
-    std::optional<AdjustmentIOU>
+    [[nodiscard]] std::optional<AdjustmentIOU>
     adjustmentsIOU(AccountID const& main, AccountID const& other, Currency const& currency) const;
 
-    std::optional<AdjustmentMPT>
+    [[nodiscard]] std::optional<AdjustmentMPT>
     adjustmentsMPT(MPTID const& mptID) const;
 
     void
@@ -104,7 +104,7 @@ public:
     // Get the adjusted owner count. Since DeferredCredits is meant to be used
     // in payments, and payments only decrease owner counts, return the max
     // remembered owner count.
-    std::optional<std::uint32_t>
+    [[nodiscard]] std::optional<std::uint32_t>
     ownerCount(AccountID const& id) const;
 
     void
@@ -179,15 +179,15 @@ public:
     }
     /** @} */
 
-    STAmount
+    [[nodiscard]] STAmount
     balanceHookIOU(AccountID const& account, AccountID const& issuer, STAmount const& amount)
         const override;
 
-    STAmount
+    [[nodiscard]] STAmount
     balanceHookMPT(AccountID const& account, MPTIssue const& issue, std::int64_t amount)
         const override;
 
-    STAmount
+    [[nodiscard]] STAmount
     balanceHookSelfIssueMPT(MPTIssue const& issue, std::int64_t amount) const override;
 
     void
@@ -212,7 +212,7 @@ public:
     void
     adjustOwnerCountHook(AccountID const& account, std::uint32_t cur, std::uint32_t next) override;
 
-    std::uint32_t
+    [[nodiscard]] std::uint32_t
     ownerCountHook(AccountID const& account, std::uint32_t count) const override;
 
     /** Apply changes to base view.
@@ -229,7 +229,7 @@ public:
     apply(PaymentSandbox& to);
     /** @} */
 
-    XRPAmount
+    [[nodiscard]] XRPAmount
     xrpDestroyed() const;
 
 private:

include/xrpl/ledger/ReadView.h

@@ -39,22 +39,22 @@ public:
     struct sles_type : detail::ReadViewFwdRange<std::shared_ptr<SLE const>>
     {
         explicit sles_type(ReadView const& view);
-        iterator
+        [[nodiscard]] iterator
         begin() const;
-        iterator
+        [[nodiscard]] iterator
         end() const;
-        iterator
+        [[nodiscard]] iterator
         upper_bound(key_type const& key) const;
     };
 
     struct txs_type : detail::ReadViewFwdRange<tx_type>
     {
         explicit txs_type(ReadView const& view);
-        bool
+        [[nodiscard]] bool
         empty() const;
-        iterator
+        [[nodiscard]] iterator
         begin() const;
-        iterator
+        [[nodiscard]] iterator
         end() const;
     };
 
@@ -78,33 +78,33 @@ public:
     }
 
     /** Returns information about the ledger. */
-    virtual LedgerHeader const&
+    [[nodiscard]] virtual LedgerHeader const&
     header() const = 0;
 
     /** Returns true if this reflects an open ledger. */
-    virtual bool
+    [[nodiscard]] virtual bool
     open() const = 0;
 
     /** Returns the close time of the previous ledger. */
-    NetClock::time_point
+    [[nodiscard]] NetClock::time_point
     parentCloseTime() const
     {
         return header().parentCloseTime;
     }
 
     /** Returns the sequence number of the base ledger. */
-    LedgerIndex
+    [[nodiscard]] LedgerIndex
     seq() const
     {
         return header().seq;
     }
 
     /** Returns the fees for the base ledger. */
-    virtual Fees const&
+    [[nodiscard]] virtual Fees const&
     fees() const = 0;
 
     /** Returns the tx processing rules. */
-    virtual Rules const&
+    [[nodiscard]] virtual Rules const&
     rules() const = 0;
 
     /** Determine if a state item exists.
@@ -114,7 +114,7 @@ public:
         @return `true` if a SLE is associated with the
                 specified key.
     */
-    virtual bool
+    [[nodiscard]] virtual bool
     exists(Keylet const& k) const = 0;
 
     /** Return the key of the next state item.
@@ -127,7 +127,7 @@ public:
         the key returned would be outside the open
         interval (key, last).
     */
-    virtual std::optional<key_type>
+    [[nodiscard]] virtual std::optional<key_type>
     succ(key_type const& key, std::optional<key_type> const& last = std::nullopt) const = 0;
 
     /** Return the state item associated with a key.
@@ -143,7 +143,7 @@ public:
         @return `nullptr` if the key is not present or
                 if the type does not match.
     */
-    virtual std::shared_ptr<SLE const>
+    [[nodiscard]] virtual std::shared_ptr<SLE const>
     read(Keylet const& k) const = 0;
 
     // Accounts in a payment are not allowed to use assets acquired during that
@@ -151,7 +151,7 @@ public:
     // changes that accounts make during a payment. `balanceHookIOU` adjusts
     // balances so newly acquired assets are not counted toward the balance.
     // This is required to support PaymentSandbox.
-    virtual STAmount
+    [[nodiscard]] virtual STAmount
     balanceHookIOU(AccountID const& account, AccountID const& issuer, STAmount const& amount) const
     {
         XRPL_ASSERT(amount.holds<Issue>(), "balanceHookIOU: amount is for Issue");
@@ -161,7 +161,7 @@ public:
 
     // balanceHookMPT adjusts balances so newly acquired assets are not counted
     // toward the balance.
-    virtual STAmount
+    [[nodiscard]] virtual STAmount
     balanceHookMPT(AccountID const& account, MPTIssue const& issue, std::int64_t amount) const
     {
         return STAmount{issue, amount};
@@ -171,7 +171,7 @@ public:
     // funds available to issue, which are originally available funds less
     // already self sold MPT amounts (MPT sell offer). This hook is used
     // by issuerFundsToSelfIssue() function.
-    virtual STAmount
+    [[nodiscard]] virtual STAmount
     balanceHookSelfIssueMPT(MPTIssue const& issue, std::int64_t amount) const
     {
         return STAmount{issue, amount};
@@ -182,30 +182,30 @@ public:
     // changes that accounts make during a payment. `ownerCountHook` adjusts the
     // ownerCount so it returns the max value of the ownerCount so far.
     // This is required to support PaymentSandbox.
-    virtual std::uint32_t
+    [[nodiscard]] virtual std::uint32_t
     ownerCountHook(AccountID const& account, std::uint32_t count) const
     {
         return count;
     }
 
     // used by the implementation
-    virtual std::unique_ptr<sles_type::iter_base>
+    [[nodiscard]] virtual std::unique_ptr<sles_type::iter_base>
     slesBegin() const = 0;
 
     // used by the implementation
-    virtual std::unique_ptr<sles_type::iter_base>
+    [[nodiscard]] virtual std::unique_ptr<sles_type::iter_base>
     slesEnd() const = 0;
 
     // used by the implementation
-    virtual std::unique_ptr<sles_type::iter_base>
+    [[nodiscard]] virtual std::unique_ptr<sles_type::iter_base>
     slesUpperBound(key_type const& key) const = 0;
 
     // used by the implementation
-    virtual std::unique_ptr<txs_type::iter_base>
+    [[nodiscard]] virtual std::unique_ptr<txs_type::iter_base>
     txsBegin() const = 0;
 
     // used by the implementation
-    virtual std::unique_ptr<txs_type::iter_base>
+    [[nodiscard]] virtual std::unique_ptr<txs_type::iter_base>
     txsEnd() const = 0;
 
     /** Returns `true` if a tx exists in the tx map.
@@ -213,7 +213,7 @@ public:
         A tx exists in the map if it is part of the
         base ledger, or if it is a newly inserted tx.
     */
-    virtual bool
+    [[nodiscard]] virtual bool
     txExists(key_type const& key) const = 0;
 
     /** Read a transaction from the tx map.
@@ -224,7 +224,7 @@ public:
         @return A pair of nullptr if the
                 key is not found in the tx map.
     */
-    virtual tx_type
+    [[nodiscard]] virtual tx_type
     txRead(key_type const& key) const = 0;
 
     //
@@ -257,7 +257,7 @@ public:
 
         @return std::nullopt if the item does not exist.
     */
-    virtual std::optional<digest_type>
+    [[nodiscard]] virtual std::optional<digest_type>
     digest(key_type const& key) const = 0;
 };
 

include/xrpl/ledger/detail/ApplyStateTable.h

@@ -54,19 +54,19 @@ public:
         bool isDryRun,
         beast::Journal j);
 
-    bool
+    [[nodiscard]] bool
     exists(ReadView const& base, Keylet const& k) const;
 
-    std::optional<key_type>
+    [[nodiscard]] std::optional<key_type>
     succ(ReadView const& base, key_type const& key, std::optional<key_type> const& last) const;
 
-    std::shared_ptr<SLE const>
+    [[nodiscard]] std::shared_ptr<SLE const>
     read(ReadView const& base, Keylet const& k) const;
 
     std::shared_ptr<SLE>
     peek(ReadView const& base, Keylet const& k);
 
-    std::size_t
+    [[nodiscard]] std::size_t
     size() const;
 
     void
@@ -97,7 +97,7 @@ public:
     destroyXRP(XRPAmount const& fee);
 
     // For debugging
-    XRPAmount const&
+    [[nodiscard]] XRPAmount const&
     dropsDestroyed() const
     {
         return dropsDestroyed_;

include/xrpl/ledger/detail/ApplyViewBase.h

@@ -22,51 +22,51 @@ public:
     ApplyViewBase(ReadView const* base, ApplyFlags flags);
 
     // ReadView
-    bool
+    [[nodiscard]] bool
     open() const override;
 
-    LedgerHeader const&
+    [[nodiscard]] LedgerHeader const&
     header() const override;
 
-    Fees const&
+    [[nodiscard]] Fees const&
     fees() const override;
 
-    Rules const&
+    [[nodiscard]] Rules const&
     rules() const override;
 
-    bool
+    [[nodiscard]] bool
     exists(Keylet const& k) const override;
 
-    std::optional<key_type>
+    [[nodiscard]] std::optional<key_type>
     succ(key_type const& key, std::optional<key_type> const& last = std::nullopt) const override;
 
-    std::shared_ptr<SLE const>
+    [[nodiscard]] std::shared_ptr<SLE const>
     read(Keylet const& k) const override;
 
-    std::unique_ptr<sles_type::iter_base>
+    [[nodiscard]] std::unique_ptr<sles_type::iter_base>
     slesBegin() const override;
 
-    std::unique_ptr<sles_type::iter_base>
+    [[nodiscard]] std::unique_ptr<sles_type::iter_base>
     slesEnd() const override;
 
-    std::unique_ptr<sles_type::iter_base>
+    [[nodiscard]] std::unique_ptr<sles_type::iter_base>
     slesUpperBound(uint256 const& key) const override;
 
-    std::unique_ptr<txs_type::iter_base>
+    [[nodiscard]] std::unique_ptr<txs_type::iter_base>
     txsBegin() const override;
 
-    std::unique_ptr<txs_type::iter_base>
+    [[nodiscard]] std::unique_ptr<txs_type::iter_base>
     txsEnd() const override;
 
-    bool
+    [[nodiscard]] bool
     txExists(key_type const& key) const override;
 
-    tx_type
+    [[nodiscard]] tx_type
     txRead(key_type const& key) const override;
 
     // ApplyView
 
-    ApplyFlags
+    [[nodiscard]] ApplyFlags
     flags() const override;
 
     std::shared_ptr<SLE>

include/xrpl/ledger/detail/RawStateTable.h

@@ -42,10 +42,10 @@ public:
     void
     apply(RawView& to) const;
 
-    bool
+    [[nodiscard]] bool
     exists(ReadView const& base, Keylet const& k) const;
 
-    std::optional<key_type>
+    [[nodiscard]] std::optional<key_type>
     succ(ReadView const& base, key_type const& key, std::optional<key_type> const& last) const;
 
     void
@@ -57,19 +57,19 @@ public:
     void
     replace(std::shared_ptr<SLE> const& sle);
 
-    std::shared_ptr<SLE const>
+    [[nodiscard]] std::shared_ptr<SLE const>
     read(ReadView const& base, Keylet const& k) const;
 
     void
     destroyXRP(XRPAmount const& fee);
 
-    std::unique_ptr<ReadView::sles_type::iter_base>
+    [[nodiscard]] std::unique_ptr<ReadView::sles_type::iter_base>
     slesBegin(ReadView const& base) const;
 
-    std::unique_ptr<ReadView::sles_type::iter_base>
+    [[nodiscard]] std::unique_ptr<ReadView::sles_type::iter_base>
     slesEnd(ReadView const& base) const;
 
-    std::unique_ptr<ReadView::sles_type::iter_base>
+    [[nodiscard]] std::unique_ptr<ReadView::sles_type::iter_base>
     slesUpperBound(ReadView const& base, uint256 const& key) const;
 
 private:

include/xrpl/ledger/detail/ReadViewFwdRange.h

@@ -27,16 +27,16 @@ public:
 
     virtual ~ReadViewFwdIter() = default;
 
-    virtual std::unique_ptr<ReadViewFwdIter>
+    [[nodiscard]] virtual std::unique_ptr<ReadViewFwdIter>
     copy() const = 0;
 
-    virtual bool
+    [[nodiscard]] virtual bool
     equal(ReadViewFwdIter const& impl) const = 0;
 
     virtual void
     increment() = 0;
 
-    virtual value_type
+    [[nodiscard]] virtual value_type
     dereference() const = 0;
 };
 

include/xrpl/ledger/helpers/LendingHelpers.h

@@ -104,7 +104,7 @@ struct LoanState
     Number managementFeeDue;
 
     // Interest still due to be paid by the borrower.
-    Number
+    [[nodiscard]] Number
     interestOutstanding() const
     {
         XRPL_ASSERT_PARTS(
@@ -266,7 +266,7 @@ struct PaymentComponents
     //
     // @return The amount of tracked interest included in this payment that
     //         will be paid to the vault.
-    Number
+    [[nodiscard]] Number
     trackedInterestPart() const;
 };
 
@@ -340,7 +340,7 @@ struct LoanStateDeltas
     /* Calculates the total change across all components.
      * @return The sum of principal, interest, and management fee deltas.
      */
-    Number
+    [[nodiscard]] Number
     total() const
     {
         return principal + interest + managementFee;

include/xrpl/net/AutoSocket.h

@@ -43,7 +43,7 @@ public:
     {
     }
 
-    bool
+    [[nodiscard]] bool
     isSecure() const
     {
         return mSecure;

include/xrpl/net/HTTPClientSSLContext.h

@@ -58,7 +58,7 @@ public:
         return ssl_context_;
     }
 
-    bool
+    [[nodiscard]] bool
     sslVerify() const
     {
         return verify_;

include/xrpl/nodestore/Backend.h

@@ -34,7 +34,7 @@ public:
 
     /** Get the block size for backends that support it
      */
-    virtual std::optional<std::size_t>
+    [[nodiscard]] virtual std::optional<std::size_t>
     getBlockSize() const
     {
         return std::nullopt;
@@ -135,7 +135,7 @@ public:
     }
 
     /** Returns the number of file descriptors the backend expects to need. */
-    virtual int
+    [[nodiscard]] virtual int
     fdRequired() const = 0;
 };
 

include/xrpl/nodestore/Factory.h

@@ -16,7 +16,7 @@ public:
     virtual ~Factory() = default;
 
     /** Retrieve the name of this factory. */
-    virtual std::string
+    [[nodiscard]] virtual std::string
     getName() const = 0;
 
     /** Create an instance of this factory's backend.

include/xrpl/nodestore/NodeObject.h

@@ -59,15 +59,15 @@ public:
     createObject(NodeObjectType type, Blob&& data, uint256 const& hash);
 
     /** Returns the type of this object. */
-    NodeObjectType
+    [[nodiscard]] NodeObjectType
     getType() const;
 
     /** Returns the hash of the data. */
-    uint256 const&
+    [[nodiscard]] uint256 const&
     getHash() const;
 
     /** Returns the underlying data. */
-    Blob const&
+    [[nodiscard]] Blob const&
     getData() const;
 
 private:

include/xrpl/nodestore/detail/DecodedBlob.h

@@ -21,7 +21,7 @@ public:
     DecodedBlob(void const* key, void const* value, int valueBytes);
 
     /** Determine if the decoding was successful. */
-    bool
+    [[nodiscard]] bool
     wasOk() const noexcept
     {
         return m_success;

include/xrpl/protocol/Asset.h

@@ -68,7 +68,7 @@ public:
     {
     }
 
-    AccountID const&
+    [[nodiscard]] AccountID const&
     getIssuer() const;
 
     template <ValidIssueType TIss>
@@ -80,16 +80,16 @@ public:
     get();
 
     template <ValidIssueType TIss>
-    constexpr bool
+    [[nodiscard]] constexpr bool
     holds() const;
 
-    std::string
+    [[nodiscard]] std::string
     getText() const;
 
-    constexpr value_type const&
+    [[nodiscard]] constexpr value_type const&
     value() const;
 
-    constexpr token_type
+    [[nodiscard]] constexpr token_type
     token() const;
 
     void
@@ -98,7 +98,7 @@ public:
     STAmount
     operator()(Number const&) const;
 
-    constexpr AmtType
+    [[nodiscard]] constexpr AmtType
     getAmountType() const;
 
     // Custom, generic visit implementation
@@ -111,7 +111,7 @@ public:
         return detail::visit(issue_, std::forward<Visitors>(visitors)...);
     }
 
-    constexpr bool
+    [[nodiscard]] constexpr bool
     native() const
     {
         return visit(
@@ -119,7 +119,7 @@ public:
             [&](MPTIssue const&) { return false; });
     }
 
-    bool
+    [[nodiscard]] bool
     integral() const
     {
         return visit(
@@ -169,7 +169,7 @@ Asset::holds() const
 }
 
 template <ValidIssueType TIss>
-constexpr TIss const&
+[[nodiscard]] constexpr TIss const&
 Asset::get() const
 {
     if (!std::holds_alternative<TIss>(issue_))

include/xrpl/protocol/Fees.h

@@ -39,7 +39,7 @@ struct Fees
         The reserve is calculated as the reserve base plus
         the reserve increment times the number of increments.
     */
-    XRPAmount
+    [[nodiscard]] XRPAmount
     accountReserve(std::size_t ownerCount) const
     {
         return reserve + ownerCount * increment;

include/xrpl/protocol/IOUAmount.h

@@ -71,13 +71,13 @@ public:
     operator bool() const noexcept;
 
     /** Return the sign of the amount */
-    int
+    [[nodiscard]] int
     signum() const noexcept;
 
-    exponent_type
+    [[nodiscard]] exponent_type
     exponent() const noexcept;
 
-    mantissa_type
+    [[nodiscard]] mantissa_type
     mantissa() const noexcept;
 
     static IOUAmount

include/xrpl/protocol/InnerObjectFormats.h

@@ -18,7 +18,7 @@ public:
     static InnerObjectFormats const&
     getInstance();
 
-    SOTemplate const*
+    [[nodiscard]] SOTemplate const*
     findSOTemplateBySField(SField const& sField) const;
 };
 

include/xrpl/protocol/Issue.h

@@ -21,22 +21,22 @@ public:
     {
     }
 
-    AccountID const&
+    [[nodiscard]] AccountID const&
     getIssuer() const
     {
         return account;
     }
 
-    std::string
+    [[nodiscard]] std::string
     getText() const;
 
     void
     setJson(Json::Value& jv) const;
 
-    bool
+    [[nodiscard]] bool
     native() const;
 
-    bool
+    [[nodiscard]] bool
     integral() const;
 
     friend constexpr std::weak_ordering

include/xrpl/protocol/Keylet.h

@@ -25,7 +25,7 @@ struct Keylet
     }
 
     /** Returns true if the SLE matches the type */
-    bool
+    [[nodiscard]] bool
     check(STLedgerEntry const&) const;
 };
 

include/xrpl/protocol/KnownFormats.h

@@ -44,7 +44,7 @@ public:
 
         /** Retrieve the name of the format.
          */
-        std::string const&
+        [[nodiscard]] std::string const&
         getName() const
         {
             return name_;
@@ -52,13 +52,13 @@ public:
 
         /** Retrieve the transaction type this format represents.
          */
-        KeyType
+        [[nodiscard]] KeyType
         getType() const
         {
             return type_;
         }
 
-        SOTemplate const&
+        [[nodiscard]] SOTemplate const&
         getSOTemplate() const
         {
             return soTemplate_;
@@ -96,7 +96,7 @@ public:
         @param  name The name of the type.
         @return      The type.
     */
-    KeyType
+    [[nodiscard]] KeyType
     findTypeByName(std::string const& name) const
     {
         if (auto const result = findByName(name))
@@ -108,7 +108,7 @@ public:
 
     /** Retrieve a format based on its type.
      */
-    Item const*
+    [[nodiscard]] Item const*
     findByType(KeyType type) const
     {
         auto const itr = types_.find(type);
@@ -118,13 +118,13 @@ public:
     }
 
     // begin() and end() are provided for testing purposes.
-    typename std::forward_list<Item>::const_iterator
+    [[nodiscard]] typename std::forward_list<Item>::const_iterator
     begin() const
     {
         return formats_.begin();
     }
 
-    typename std::forward_list<Item>::const_iterator
+    [[nodiscard]] typename std::forward_list<Item>::const_iterator
     end() const
     {
         return formats_.end();
@@ -133,7 +133,7 @@ public:
 protected:
     /** Retrieve a format based on its name.
      */
-    Item const*
+    [[nodiscard]] Item const*
     findByName(std::string const& name) const
     {
         auto const itr = names_.find(name);

include/xrpl/protocol/MPTAmount.h

@@ -68,14 +68,14 @@ public:
     }
 
     /** Return the sign of the amount */
-    constexpr int
+    [[nodiscard]] constexpr int
     signum() const noexcept;
 
     /** Returns the underlying value. Code SHOULD NOT call this
         function unless the type has been abstracted away,
         e.g. in a templated function.
     */
-    constexpr value_type
+    [[nodiscard]] constexpr value_type
     value() const;
 
     static MPTAmount

include/xrpl/protocol/MPTIssue.h

@@ -26,16 +26,16 @@ public:
         return mptID_;
     }
 
-    AccountID const&
+    [[nodiscard]] AccountID const&
     getIssuer() const;
 
-    constexpr MPTID const&
+    [[nodiscard]] constexpr MPTID const&
     getMptID() const
     {
         return mptID_;
     }
 
-    std::string
+    [[nodiscard]] std::string
     getText() const;
 
     void

include/xrpl/protocol/MultiApiJson.h

@@ -156,7 +156,7 @@ struct MultiApiJson
         { return visitor(*self, std::forward<decltype(args)>(args)...); };
     }
 
-    auto
+    [[nodiscard]] auto
     visit() const
     {
         return [self = this](auto... args)
@@ -176,7 +176,7 @@ struct MultiApiJson
     }
 
     template <typename... Args>
-    auto
+    [[nodiscard]] auto
     visit(Args... args) const -> std::invoke_result_t<visitor_t, MultiApiJson const&, Args...>
         requires(sizeof...(args) > 0) &&
         requires { visitor(*this, std::forward<decltype(args)>(args)...); }

include/xrpl/protocol/PathAsset.h

@@ -24,17 +24,17 @@ public:
     }
 
     template <ValidPathAsset T>
-    constexpr bool
+    [[nodiscard]] constexpr bool
     holds() const;
 
-    constexpr bool
+    [[nodiscard]] constexpr bool
     isXRP() const;
 
     template <ValidPathAsset T>
     T const&
     get() const;
 
-    constexpr std::variant<Currency, MPTID> const&
+    [[nodiscard]] constexpr std::variant<Currency, MPTID> const&
     value() const;
 
     // Custom, generic visit implementation

include/xrpl/protocol/Permissions.h

@@ -53,22 +53,22 @@ public:
     Permission&
     operator=(Permission const&) = delete;
 
-    std::optional<std::string>
+    [[nodiscard]] std::optional<std::string>
     getPermissionName(std::uint32_t const value) const;
 
-    std::optional<std::uint32_t>
+    [[nodiscard]] std::optional<std::uint32_t>
     getGranularValue(std::string const& name) const;
 
-    std::optional<std::string>
+    [[nodiscard]] std::optional<std::string>
     getGranularName(GranularPermissionType const& value) const;
 
-    std::optional<TxType>
+    [[nodiscard]] std::optional<TxType>
     getGranularTxType(GranularPermissionType const& gpType) const;
 
-    std::optional<std::reference_wrapper<uint256 const>>
+    [[nodiscard]] std::optional<std::reference_wrapper<uint256 const>>
     getTxFeature(TxType txType) const;
 
-    bool
+    [[nodiscard]] bool
     isDelegable(std::uint32_t const& permissionValue, Rules const& rules) const;
 
     // for tx level permission, permission value is equal to tx type plus one

include/xrpl/protocol/PublicKey.h

@@ -63,7 +63,7 @@ public:
     */
     explicit PublicKey(Slice const& slice);
 
-    std::uint8_t const*
+    [[nodiscard]] std::uint8_t const*
     data() const noexcept
     {
         return buf_;
@@ -75,31 +75,31 @@ public:
         return size_;
     }
 
-    const_iterator
+    [[nodiscard]] const_iterator
     begin() const noexcept
     {
         return buf_;
     }
 
-    const_iterator
+    [[nodiscard]] const_iterator
     cbegin() const noexcept
     {
         return buf_;
     }
 
-    const_iterator
+    [[nodiscard]] const_iterator
     end() const noexcept
     {
         return buf_ + size_;
     }
 
-    const_iterator
+    [[nodiscard]] const_iterator
     cend() const noexcept
     {
         return buf_ + size_;
     }
 
-    Slice
+    [[nodiscard]] Slice
     slice() const noexcept
     {
         return {buf_, size_};

include/xrpl/protocol/Quality.h

@@ -35,7 +35,7 @@ struct TAmounts
     }
 
     /** Returns `true` if either quantity is not positive. */
-    bool
+    [[nodiscard]] bool
     empty() const noexcept
     {
         return in <= beast::zero || out <= beast::zero;
@@ -145,7 +145,7 @@ public:
     /** @} */
 
     /** Returns the quality as STAmount. */
-    STAmount
+    [[nodiscard]] STAmount
     rate() const
     {
         return amountFromQuality(m_value);
@@ -154,7 +154,7 @@ public:
     /** Returns the quality rounded up to the specified number
         of decimal digits.
     */
-    Quality
+    [[nodiscard]] Quality
     round(int tickSize) const;
 
     /** Returns the scaled amount with in capped.

include/xrpl/protocol/QualityFunction.h

@@ -53,13 +53,13 @@ public:
 
     /** Return true if the quality function is constant
      */
-    bool
+    [[nodiscard]] bool
     isConst() const
     {
         return quality_.has_value();
     }
 
-    std::optional<Quality> const&
+    [[nodiscard]] std::optional<Quality> const&
     quality() const
     {
         return quality_;

include/xrpl/protocol/Rules.h

@@ -58,12 +58,12 @@ private:
         std::optional<uint256> const& digest,
         STVector256 const& amendments);
 
-    std::unordered_set<uint256, beast::uhash<>> const&
+    [[nodiscard]] std::unordered_set<uint256, beast::uhash<>> const&
     presets() const;
 
 public:
     /** Returns `true` if a feature is enabled. */
-    bool
+    [[nodiscard]] bool
     enabled(uint256 const& feature) const;
 
     /** Returns `true` if two rule sets are identical.

include/xrpl/protocol/SField.h

@@ -189,19 +189,19 @@ public:
         return getField(field_code(type, value));
     }
 
-    std::string const&
+    [[nodiscard]] std::string const&
     getName() const
     {
         return fieldName;
     }
 
-    bool
+    [[nodiscard]] bool
     hasName() const
     {
         return fieldCode > 0;
     }
 
-    Json::StaticString const&
+    [[nodiscard]] Json::StaticString const&
     getJsonName() const
     {
         return jsonName;
@@ -212,19 +212,19 @@ public:
         return jsonName;
     }
 
-    bool
+    [[nodiscard]] bool
     isInvalid() const
     {
         return fieldCode == -1;
     }
 
-    bool
+    [[nodiscard]] bool
     isUseful() const
     {
         return fieldCode > 0;
     }
 
-    bool
+    [[nodiscard]] bool
     isBinary() const
     {
         return fieldValue < 256;
@@ -234,18 +234,18 @@ public:
     // should be discarded during serialization,like 'hash'.
     // You cannot serialize an object's hash inside that object,
     // but you can have it in the JSON representation.
-    bool
+    [[nodiscard]] bool
     isDiscardable() const
     {
         return fieldValue > 256;
     }
 
-    int
+    [[nodiscard]] int
     getCode() const
     {
         return fieldCode;
     }
-    int
+    [[nodiscard]] int
     getNum() const
     {
         return fieldNum;
@@ -256,13 +256,13 @@ public:
         return num;
     }
 
-    bool
+    [[nodiscard]] bool
     shouldMeta(int c) const
     {
         return (fieldMeta & c) != 0;
     }
 
-    bool
+    [[nodiscard]] bool
     shouldInclude(bool withSigningField) const
     {
         return (fieldValue < 256) && (withSigningField || (signingField == IsSigning::yes));

include/xrpl/protocol/SOTemplate.h

@@ -63,19 +63,19 @@ public:
         init(fieldName);
     }
 
-    SField const&
+    [[nodiscard]] SField const&
     sField() const
     {
         return sField_.get();
     }
 
-    SOEStyle
+    [[nodiscard]] SOEStyle
     style() const
     {
         return style_;
     }
 
-    SOETxMPTIssue
+    [[nodiscard]] SOETxMPTIssue
     supportMPT() const
     {
         return supportMpt_;
@@ -110,42 +110,42 @@ public:
         std::initializer_list<SOElement> commonFields = {});
 
     /* Provide for the enumeration of fields */
-    std::vector<SOElement>::const_iterator
+    [[nodiscard]] std::vector<SOElement>::const_iterator
     begin() const
     {
         return elements_.cbegin();
     }
 
-    std::vector<SOElement>::const_iterator
+    [[nodiscard]] std::vector<SOElement>::const_iterator
     cbegin() const
     {
         return begin();
     }
 
-    std::vector<SOElement>::const_iterator
+    [[nodiscard]] std::vector<SOElement>::const_iterator
     end() const
     {
         return elements_.cend();
     }
 
-    std::vector<SOElement>::const_iterator
+    [[nodiscard]] std::vector<SOElement>::const_iterator
     cend() const
     {
         return end();
     }
 
     /** The number of entries in this template */
-    std::size_t
+    [[nodiscard]] std::size_t
     size() const
     {
         return elements_.size();
     }
 
     /** Retrieve the position of a named field. */
-    int
+    [[nodiscard]] int
     getIndex(SField const&) const;
 
-    SOEStyle
+    [[nodiscard]] SOEStyle
     style(SField const& sf) const
     {
         return elements_[indices_[sf.getNum()]].style();

include/xrpl/protocol/STAccount.h

@@ -28,25 +28,25 @@ public:
     STAccount(SerialIter& sit, SField const& name);
     STAccount(SField const& n, AccountID const& v);
 
-    SerializedTypeID
+    [[nodiscard]] SerializedTypeID
     getSType() const override;
 
-    std::string
+    [[nodiscard]] std::string
     getText() const override;
 
     void
     add(Serializer& s) const override;
 
-    bool
+    [[nodiscard]] bool
     isEquivalent(STBase const& t) const override;
 
-    bool
+    [[nodiscard]] bool
     isDefault() const override;
 
     STAccount&
     operator=(AccountID const& value);
 
-    AccountID const&
+    [[nodiscard]] AccountID const&
     value() const noexcept;
 
     void

include/xrpl/protocol/STAmount.h

@@ -138,26 +138,26 @@ public:
     //
     //--------------------------------------------------------------------------
 
-    int
+    [[nodiscard]] int
     exponent() const noexcept;
 
-    bool
+    [[nodiscard]] bool
     integral() const noexcept;
 
-    bool
+    [[nodiscard]] bool
     native() const noexcept;
 
     template <ValidIssueType TIss>
-    constexpr bool
+    [[nodiscard]] constexpr bool
     holds() const noexcept;
 
-    bool
+    [[nodiscard]] bool
     negative() const noexcept;
 
-    std::uint64_t
+    [[nodiscard]] std::uint64_t
     mantissa() const noexcept;
 
-    Asset const&
+    [[nodiscard]] Asset const&
     asset() const;
 
     template <ValidIssueType TIss>
@@ -168,20 +168,20 @@ public:
     TIss&
     get();
 
-    AccountID const&
+    [[nodiscard]] AccountID const&
     getIssuer() const;
 
-    int
+    [[nodiscard]] int
     signum() const noexcept;
 
     /** Returns a zero value with the same issuer and currency. */
-    STAmount
+    [[nodiscard]] STAmount
     zeroed() const;
 
     void
     setJson(Json::Value&) const;
 
-    STAmount const&
+    [[nodiscard]] STAmount const&
     value() const noexcept;
 
     //--------------------------------------------------------------------------
@@ -232,31 +232,31 @@ public:
     //
     //--------------------------------------------------------------------------
 
-    SerializedTypeID
+    [[nodiscard]] SerializedTypeID
     getSType() const override;
 
-    std::string
+    [[nodiscard]] std::string
     getFullText() const override;
 
-    std::string
+    [[nodiscard]] std::string
     getText() const override;
 
-    Json::Value getJson(JsonOptions = JsonOptions::none) const override;
+    [[nodiscard]] Json::Value getJson(JsonOptions = JsonOptions::none) const override;
 
     void
     add(Serializer& s) const override;
 
-    bool
+    [[nodiscard]] bool
     isEquivalent(STBase const& t) const override;
 
-    bool
+    [[nodiscard]] bool
     isDefault() const override;
 
-    XRPAmount
+    [[nodiscard]] XRPAmount
     xrp() const;
-    IOUAmount
+    [[nodiscard]] IOUAmount
     iou() const;
-    MPTAmount
+    [[nodiscard]] MPTAmount
     mpt() const;
 
 private:
@@ -462,7 +462,7 @@ STAmount::asset() const
 }
 
 template <ValidIssueType TIss>
-constexpr TIss const&
+[[nodiscard]] constexpr TIss const&
 STAmount::get() const
 {
     return mAsset.get<TIss>();