Hello
I just wrote a simple MinGW program (more or less, the library templates
there are not necessarily small) where I built an exception class around
the "System Error Codes" in Win API returned by ::GetLastError() function.
Than I want to throw such an exception, with the call to GetLastError
directly as the argument to the constructor:
throw WinapiException(::GetLastError())
Much to my surprise, ::GetLastError() appears to return 0 (success),
even after an API function returns failure. I used an API monitoring
tool (listing all calls to .dll functions from my program), and I find
that upon the first throw statement encountered, libgcc_s_dw2-1.dll also
calls ::CreateSemaphore() and ::TlsAlloc(), and even ::GetLastError(),
before my WinapiException() constructor gets called. I used gdb to break
on ::CreateSemaphore, to confirm the backtrace. I guess it is something
like an "exception allocation code" generated by the compiler, with
library support.
Which is ok, except that it looses the value for ::GetLastError().
I don't want to be blunt, but it kind of breaks the API function, and
regular users do not know to look for and use an API monitoring tool.
Can this be fixed please ?
MinGW is now on gcc v4.6.2 (issue also reported on 4.6.1), and the folks
there say they do not modify gcc sources. The issue was first posted there:
http://thread.gmane.org/gmane.comp.gnu.mingw.user/38821
You can see my code here (file winapi++.hh, line 168, has the throw
statement):
api-generics.hh http://pastebin.com/xPZU6JZd
winapi++.hh http://pastebin.com/YU1Cuqir
winapi++.cc http://pastebin.com/JqTEgPnY
realpath.cc http://pastebin.com/pvTHfQUJ
Makefile http://pastebin.com/UjZj89Kx
Thank you,
Timothy Madden
