I know there have been previous discussions about the warnings emitted from abi_prefix.hpp and abi_suffix.hpp on Win64. Was there ever any resolution? To recap, for every header which uses the ABI bookends, the compiler emits four warnings: abi_prefix.hpp(19) : warning C4103: 'abi_prefix.hpp' : alignment changed after including header, may be due to missing #pragma pack(pop) exceptions.hpp(22) : warning C4103: 'exceptions.hpp' : alignment changed after including header, may be due to missing #pragma pack(pop) abi_suffix.hpp(20) : warning C4103: 'abi_suffix.hpp' : alignment changed after including header, may be due to missing #pragma pack(pop) exceptions.hpp(108) : warning C4103: 'exceptions.hpp' : alignment changed after including header, may be due to missing #pragma pack(pop) I'm unclear on the rationale for forcing 8-byte alignment in config/abi/msvc_(pre|suf)fix.hpp: 8-byte alignment is the compiler default. Is there concern over Boost headers being included in a context where the alignment has been otherwise artificially altered? Assuming that's the case, I would like to propose adding a warning suppression to config/warning_disable.hpp to silence this particular warning. Here's a diff of what I'm proposing: @@ -43,5 +43,14 @@ // std library function is encountered. # pragma warning(disable:1786) #endif +#if defined(_MSC_VER) && defined(_M_X64) + // warning: 'file': alignment changed after including header, may + // be due to missing #pragma pack(pop) + // + // Caused by MSVC-specific abi_prefix and abi_suffix bookends which + // twiddle the default structure alignment via #pragma pack(); this + // results in a warning only on x86_64 targets. +# pragma warning(disable:4103) +#endif #endif // BOOST_CONFIG_WARNING_DISABLE_HPP I'd like to get something in for Boost 1.37 as this warning is responsible for a significant amount of spam in our build logs. Comments? -Chris