Bugs item #425021, was opened at 2001-05-17 17:03
You can respond by visiting:
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Category: gcc
Group: Known bugs
>Status: Closed
>Resolution: Fixed
Priority: 5
Submitted By: David Gravereaux (davygrvy)
Assigned to: Nobody/Anonymous (nobody)
Summary: Structured Exception Handling missing
Initial Comment:
Although Win32 SEH is an OS `feature`, it requires new
language semantics:
http://msdn.microsoft.com/library/devprods/vs6/visualc/
vccore/_core_exception_handling_topics_.28.seh.29.htm
The attached file should compile with mingw.
The M$VC++ understands it:
D:\itcl_exp>cl -c SEHtest.c
Microsoft (R) 32-bit C/C++ Optimizing Compiler Version
12.00.8804 for 80x86
Copyright (C) Microsoft Corp 1984-1998. All rights
reserved.
sehtest.c
D:\itcl_exp>
MinGW does not:
daveg@... d:/itcl_exp
$ gcc -c -mno-cygwin SEHtest.c
SEHtest.c: In function `SomeCloseProc':
SEHtest.c:7: `__try' undeclared (first use in this
function)
SEHtest.c:7: (Each undeclared identifier is reported
only once
SEHtest.c:7: for each function it appears in.)
SEHtest.c:7: parse error before `{'
SEHtest.c: At top level:
SEHtest.c:11: syntax error before `{'
SEHtest.c:15: parse error before `1'
SEHtest.c:18: parse error before `return'
daveg@... d:/itcl_exp
$
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>Comment By: David Gravereaux (davygrvy)
Date: 2001-11-06 22:27
Message:
Logged In: YES
user_id=7549
I've found this to be repaired, thank you!
----------------------------------------------------------------------
Comment By: Nobody/Anonymous (nobody)
Date: 2001-08-19 04:20
Message:
Logged In: NO
MinGW has minimal support for SEH:
following example Programm demonstrates how to use it:
#include <windows.h>
int bad(int &b) ;
EXCEPTION_DISPOSITION _catch1(struct _EXCEPTION_RECORD*,
void*, struct _CONTEXT*, void*);
int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE
hPrevInstance,
PSTR szCmdLine, int iCmdShow)
{
try {
__try1(_catch1)
int a, b;
a = bad(b);
__except1
} catch(...) {
MessageBox (0,"Exception arised", "Bye
Bye", MB_OK);
return 0;
};
return 0;
}
int bad(int &b)
{
int (*foo)() = NULL;
foo();
return b;
}
EXCEPTION_DISPOSITION _catch1(struct _EXCEPTION_RECORD*,
void* err, struct _CONTEXT* , void* par)
{
throw 1;
}
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Comment By: David Gravereaux (davygrvy)
Date: 2001-05-17 20:23
Message:
Logged In: YES
user_id=7549
My mistake, _except_list is a variable with an unknown
location. I can't find it.
I found these export, though:
144 8F 0000DACD _abnormal_termination
206 CD 0000DB11 _except_handler3
270 10D 0000DA23 _global_unwind2
326 145 0000DA65 _local_unwind2
432 1AF 0000DBCE _seh_longjmp_unwind
Some yummy MASM assembly stuff about the direct method
which may explain some of this :)
http://spiff.tripnet.se/~iczelion/Exceptionhandling.html
Sorry for pouring this on thick.. I'm trying to be helpful.
----------------------------------------------------------------------
Comment By: David Gravereaux (davygrvy)
Date: 2001-05-17 19:38
Message:
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If it is at all helpful, here is the listings output of
SEHtest.c from:
cl -c -FAs -MD sehtest.c
Notice the use of _except_handler3 and _except_list
functions. Ok, so the helper code is already in the
runtime... Just use it.
----------------------------------------------------------------------
Comment By: David Gravereaux (davygrvy)
Date: 2001-05-17 19:26
Message:
Logged In: YES
user_id=7549
If it helps, and you have the free borland compiler, have a
look in the include directory at excpt.h
Oh! MSVC++6 has excpt.h as well. Three functions are
defined:
unsigned long __cdecl _exception_code(void);
void * __cdecl _exception_info(void);
int __cdecl _abnormal_termination(void);
But the damn M$ guys didn't seem to put them in the c-
runtime sources. I see exsup.inc and that's the closest I
can find to what the intrinsics are.
It appears that three asm files were used: exsup.asm,
exsup2.asm, and exsup3.asm. The object files are there,
but the source appears missing.
----------------------------------------------------------------------
Comment By: David Gravereaux (davygrvy)
Date: 2001-05-17 19:25
Message:
Logged In: YES
user_id=7549
>Can you show me in the ANSI standard or any standard for
>that matter where SEH is defined as "built-in language
>statement"?
Agreed! It won't be there.
>I agree that SEH is useful and very important to some
>users, and I wish I knew enough about assembly programming
>to do something about it. But...
Same. The author of LCC-Win32 added it and you might
consider grabbing his source. His compiler doesn't support
termination handlers, though. It coughs at __finally.
http://www.q-software-solutions.com/lccwin32/
>BTW TCL 8.3.3 can be compiled with mingw, with a few
simple
>patches to the __try blocks, which essentially convert
them
>to no-ops. Crashes aren't handled very gracefully, but it
>will compile and run. I have been intending to submit
>patches to TCL but have been delayed by the change in host
>of their site.
Send bugs/patches to me or https://sourceforge.net/tracker/?
group_id=10894
There's a new sticky-point in part of 8.4a2 that _requires_
the use of SEH to determine if a handle is valid. See
http://cvs.sourceforge.net/cgi-
bin/viewcvs.cgi/tcl/tcl/win/tclWinChan.c?rev=1.13&content-
type=text/vnd.viewcvs-markup
in Tcl_MakeFileChannel() about 3/4 the way down.
I'm sure there's a better way to do that test, and I'll
have to work on a solution to it, if SEH is a no-op. FYI,
a Win2K OS bug caused that test to be added. Thanks for
the input :)
----------------------------------------------------------------------
Comment By: Danny Smith (dannysmith)
Date: 2001-05-17 17:43
Message:
Logged In: YES
user_id=11494
Can you show me in the ANSI standard or any standard for
that matter where SEH is defined as "built-in language
statement"?
I agree that SEH is useful and very important to some
users, and I wish I knew enough about assembly programming
to do something about it. But...
BTW TCL 8.3.3 can be compiled with mingw, with a few simple
patches to the __try blocks, which essentially convert them
to no-ops. Crashes aren't handled very gracefully, but it
will compile and run. I have been intending to submit
patches to TCL but have been delayed by the change in host
of their site.
Danny
----------------------------------------------------------------------
Comment By: David Gravereaux (davygrvy)
Date: 2001-05-17 17:16
Message:
Logged In: YES
user_id=7549
SEHtest.c:7: `__try' undeclared (first use in this function)
__try is not a function. __try is a built-in language
statement, and has semantics, to implement SEH. __leave is
only valid within a __try block. GetExceptionCode() is not
a function either. It's a keyword only valid within the
except filter. I could keep going on defining the rules,
but I'll save my typing energy for other things :)
Please don't consider this an M$ hack job. SEH is very
important to some users, like myself. Tcl cannot be
compiled by MinGW due to this missing feature.
----------------------------------------------------------------------
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