Unreachable code

[JVApen]

I'm logging this bug because we already have several occurrences of this on our codebase.
Unfortunately, I still haven't been able to figure out what is causing it and still don't have CReduce working on Windows.

Found in boost version 1.77

boost\container\vector.hpp(138) : error C2220: the following warning is treated as an error
boost\container\vector.hpp(138) : warning C4702: unreachable code
boost\container\vector.hpp(1820) : warning C4702: unreachable code

This warning does not occur without optimization flags, it does with /O2. We are using the visual studio compiler on version 14.28

The related code:

136|    //Constructors
137|   BOOST_CONTAINER_FORCEINLINE vec_iterator() BOOST_NOEXCEPT_OR_NOTHROW
138|      : m_ptr()   //Value initialization to achieve "null iterators" (N3644)
139|   {}

1808|    template<class ...Args>
1809|   BOOST_CONTAINER_FORCEINLINE reference emplace_back(BOOST_FWD_REF(Args)...args)
1810|   {
1811|      T* const p = this->priv_raw_end();
1812|      if (BOOST_LIKELY(this->room_enough())){
1813|         //There is more memory, just construct a new object at the end
1814|         allocator_traits_type::construct(this->m_holder.alloc(), p, ::boost::forward<Args>(args)...);
1815|         ++this->m_holder.m_size;
1816|         return *p;
1817|      }
1818|      else{
1819|         typedef dtl::insert_emplace_proxy<allocator_type, T*, Args...> proxy_t;
1820|         return *this->priv_insert_forward_range_no_capacity
1821|            (p, 1, proxy_t(::boost::forward<Args>(args)...), alloc_version());
1822|      }
1823|   }

We don't use vector directly, it's either via flat_map/flat_set/small_vector/static_vector/...

[Ion Gaztañaga]

They seem false positives, as they don't appear to happen in other compilers. I've disabled that warning for Boost.Container in the following commit:

c4cfad7