[Mingw-users] GetLastError strange behaviour

[benjamin]

Hello,

this is the code snippet:
http://ideone.com/arIAm

on MinGW 4.6.1 the output is : "dwLastError 0"
on MinGW 4.5.0 and 4.5.2 its : "dwLastError 1337" which is the desired
output.

if i write the foobar function like this :
http://ideone.com/5XX80

then it also works on 4.6.1 with "dwLastError 1337".

I dont know what exactly is going on, but i think it could be a MinGW bug. What do you think?

greetings

[Earnie Boyd]

Well not, MinGW, particularly but maybe GCC. Does it work if you change
throw Win32Exception(GetLastError());
to
throw Win32Exception((DWORD)GetLastError());

--
Earnie
-- https://sites.google.com/site/earnieboyd

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[benjamin]

Am 03.03.2012 18:29, schrieb Earnie Boyd:
> On Sat, Mar 3, 2012 at 6:32 AM, benjamin<bew...@online.de> wrote:
>> Hello,
>>
>> this is the code snippet:
>> http://ideone.com/arIAm
>>
>> on MinGW 4.6.1 the output is : "dwLastError 0"
>> on MinGW 4.5.0 and 4.5.2 its : "dwLastError 1337" which is the desired
>> output.
>>
>> if i write the foobar function like this :
>> http://ideone.com/5XX80
>>
>> then it also works on 4.6.1 with "dwLastError 1337".
>>
>> I dont know what exactly is going on, but i think it could be a MinGW bug.
>> What do you think?
>>
> Well not, MinGW, particularly but maybe GCC. Does it work if you change
> throw Win32Exception(GetLastError());
> to
> throw Win32Exception((DWORD)GetLastError());
>

No it doesnt help. I only can assume about possible reasons for this
behaviour. Maybe someone has a explanation for it, or its simply a bug.

greetings

[Timothy Madden]

On 03.03.2012 19:29, Earnie Boyd wrote:
> On Sat, Mar 3, 2012 at 6:32 AM, benjamin<bew...@online.de> wrote:
>> Hello,
>>
>> this is the code snippet:
>> http://ideone.com/arIAm
>>
>> on MinGW 4.6.1 the output is : "dwLastError 0"
>> on MinGW 4.5.0 and 4.5.2 its : "dwLastError 1337" which is the desired
>> output.
>>
>> if i write the foobar function like this :
>> http://ideone.com/5XX80
>>
>> then it also works on 4.6.1 with "dwLastError 1337".
>>
>> I dont know what exactly is going on, but i think it could be a MinGW bug.
>> What do you think?
>>
>
> Well not, MinGW, particularly but maybe GCC. Does it work if you change
> throw Win32Exception(GetLastError());
> to
> throw Win32Exception((DWORD)GetLastError());
>

Can this be fixed please ? I have just run into it, and I think it is a
bug because it breaks functionality in Windows API (from the user's
perspective).

I used an API monitoring application, that would list all WinAPI
functions that are being called by my program, and so I find that on the
first throw statement (before the first Win32Exception is constructed)
there are several several other system calls before my call to
GetLastError(): malloc() which calls HeapAlloc(),
InterlockedIncrement(), InterlockedDecrement(), CreateSemaphore(),
TlsAlloc() and GetLastError().

Of these, CreateSempahore() was the first to reset the value of
GetLastError().

The calls are listed as originating from that libgcc_s_dw2-1.dll file,
except for malloc which was originating from libstdc++.

I can understand that exceptions may need additional maintenance from
the support libraries, but I think such libraries should save and
restore the value of GetLastError() if they need to change it.

I can post the example program and the list of API and .dll calls if
anyone is interested.

Thank you,
Timothy Madden

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[Earnie Boyd]

On Tue, Mar 20, 2012 at 7:31 PM, Timothy Madden <termin...@gmail.com> wrote:
>
> Can this be fixed please ? I have just run into it, and I think it is a
> bug because it breaks functionality in Windows API (from the user's
> perspective).
>

Not, here. You'll have to take it up with GCC and LIBSTDC++ lists.
We use the sources as distributed by GCC.

--
Earnie
-- https://sites.google.com/site/earnieboyd

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