id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
8925	libs/log/src/event.cpp: might not retireve last error correctly	Jeffrey Walton <noloader@…>	Andrey Semashev	"The following code may not retrieve the last error correctly.

if (WaitForSingleObject(m_event, INFINITE) != 0)
{
    BOOST_THROW_EXCEPTION(system::system_error(
      GetLastError(), system::system_category(), ""Failed to block on Windows event""));
}

If the compile evaluates the args in BOOST_THROW_EXCEPTION from left to right, system::system_error could call on a Win32 API that blows away the error. Conversely, if the args are evaluated right to left, then system::system_category() or the ""Failed to block on Windows event"" string could cause last error to get blown away.

My apologies for the write-up. After looking at a number of uses of WaitForSingleObject in Boost, this is one of the few (fewer than 5) that is correct.

Perhaps something like below would be easier to audit for correctness:

if (WaitForSingleObject(m_event, INFINITE) != 0)
{
    DWORD dwError = GetLastError();
    BOOST_THROW_EXCEPTION(system::system_error(
      dwError, system::system_category(), ""Failed to block on Windows event""));
}"	Bugs	closed	To Be Determined	log	Boost 1.54.0	Problem	fixed	GetLastError Win32 API failure