If you're compiling in C++17 mode you can't keep the ABI anyway because (as you note) the different throw spec, so here's a proposed patch:

diff --git
index bc6ba30..0f9c318 100644
---
+++
@@ -61,7 +61,11 @@ namespace mysqlpp {
 #endif


+#if __cplusplus < 201703L
+BeecryptMutex::BeecryptMutex() throw (MutexFailed)
+#else
 BeecryptMutex::BeecryptMutex() noexcept(false)
+#endif
 #if defined(ACTUALLY_DOES_SOMETHING)
        : pmutex_(new bc_mutex_t)
 #endif
@@ -103,7 +107,11 @@ BeecryptMutex::~BeecryptMutex()


 void
+#if __cplusplus < 201703L
+BeecryptMutex::lock() throw (MutexFailed)
+#else
 BeecryptMutex::lock() noexcept(false)
+#endif
 {
 #if defined(MYSQLPP_PLATFORM_WINDOWS)
        if (WaitForSingleObject(impl_val(pmutex_), INFINITE) == WAIT_OBJECT_0)
@@ -125,7 +133,11 @@ BeecryptMutex::lock() noexcept(false)


 bool
+#if __cplusplus < 201703L
+BeecryptMutex::trylock() throw (MutexFailed)
+#else
 BeecryptMutex::trylock() noexcept(false)
+#endif
 {
 #if defined(ACTUALLY_DOES_SOMETHING)
 #      if defined(MYSQLPP_PLATFORM_WINDOWS)
@@ -160,7 +172,11 @@ BeecryptMutex::trylock() noexcept(false)


 void
+#if __cplusplus < 201703L
+BeecryptMutex::unlock() throw (MutexFailed)
+#else
 BeecryptMutex::unlock() noexcept(false)
+#endif
 {
 #if defined(MYSQLPP_PLATFORM_WINDOWS)
        if (!ReleaseMutex(impl_val(pmutex_)))
diff --git
index a5850f3..0457950 100644
---
+++
@@ -61,7 +61,11 @@ public:

        Throws a MutexFailed exception if we can't acquire the lock for
        some reason.  The exception contains a message saying why.
+#if __cplusplus < 201703L
+       BeecryptMutex() throw (MutexFailed);
+#else
         BeecryptMutex() noexcept(false);
+#endif

        \brief Destroy the mutex

@@ -70,14 +74,26 @@ public:

        \brief Acquire the mutex, blocking if it can't be acquired
        immediately.
+#if __cplusplus < 201703L
+       void lock() throw (MutexFailed);
+#else
        void lock() noexcept(false);
+#endif

        \brief Acquire the mutex immediately and return true, or return
        false if it would have to block to acquire the mutex.
+#if __cplusplus < 201703L
+       bool trylock() throw (MutexFailed);
+#else
        bool trylock() noexcept(false);
+#endif

        \brief Release the mutex
+#if __cplusplus < 201703L
+       void unlock() throw (MutexFailed);
+#else
        void unlock() noexcept(false);
+#endif

 private:
        void* pmutex_;
diff --git
index a9e0641..5d15696 100644
---
+++
@@ -416,7 +416,11 @@ SQLTypeAdapter::assign(const null_type&)
 }

 char
+#if __cplusplus < 201703L
+SQLTypeAdapter::at(size_type i) const throw(std::out_of_range)
+#else
 SQLTypeAdapter::at(size_type i) const noexcept(false)
+#endif
 {
        if (buffer_) {
                if (i <= length()) {
diff --git
index 2343d69..d7b8f48 100644
---
+++
@@ -221,7 +221,11 @@ public:
        WARNING: The throw-spec is incorrect, but it can't be changed
        until v4, where we can break the ABI.  Throw-specs shouldn't be
        relied on anyway.
+#if __cplusplus < 201703L
+       char at(size_type i) const throw(std::out_of_range);
+#else
        char at(size_type i) const noexcept(false);
+#endif

        \brief Compare the internal buffer to the given string