Re: compile error about destructor
Hi Ben,
void fhelper(void)
{
this_could_fail();
auto_ptr<T> temp = new T();
temp->something_likely_to_fail();
}
void f2(void)
{
__try {
fhelper();
}
__finally {
}
}
Now the local inside fhelper can be properly unwound when a structured
exception is thrown, because they exist in a unique stack frame that the
compiler support for SEH knows how to deal with.
In your solution, you cares about whether the destructor of local will be
called or not. I think you mean variable temp in your case, which is the only
local variable.
When there is structured exception thrown, I think even if you do not put
the __try block into another function, destructor of temp will still be
called? Because either structured or unstructured (C++ exception) will make
stack unwinding. It is my mistake before which think structured exception
will not cause stack unwinding, but through testing, it will.
Why do you think if we put everything into one function will not invoke
temp's destructor? I think even if there is structured exception in
something_likely_to_fail, destructor of temp is still called.
Any more description please? Or you write a simple sample to prove your ideas?
regards,
George
"Ben Voigt [C++ MVP]" wrote:
George wrote:
Thanks Ben,
1.
With /EHa, SEH and C++ exceptions may be mixed, but not in the same
I agree and this is what we proved in his thread before.
2.
function. Separate the __try block body into a separate function.
What do you mean separate the __try block into another function? We
George, why do you always misquote people? I did not say "separate the
__try block into another function", but "Separate the __try block body into
a separate function."
For example, this can't work:
void f(void)
{
__try {
this_could_fail();
auto_ptr<T> temp = new T();
temp->something_likely_to_fail();
}
__finally {
}
}
The problem is the mixing of C++ destructors with SEH, because both need
unwinding. Whether the destructor for temp should be called depends on
whether the constructor completed. So we make the body of the __try block a
separate function:
void fhelper(void)
{
this_could_fail();
auto_ptr<T> temp = new T();
temp->something_likely_to_fail();
}
void f2(void)
{
__try {
fhelper();
}
__finally {
}
}
Now the local inside fhelper can be properly unwound when a structured
exception is thrown, because they exist in a unique stack frame that the
compiler support for SEH knows how to deal with.
always provide try/catch or __try/__except into the same function. I
am confused. Could ytou provide some pseudo code to show your points
please?
regards,
Geprge
"Ben Voigt [C++ MVP]" wrote:
Igor Tandetnik wrote:
"George" <George@discussions.microsoft.com> wrote in message
news:625FF32F-F1B8-4989-B476-8272396CA81A@microsoft.com
I compile with /EHa, and not /EHsc, and this is why I have
confusion there is such error.
Double-check your project settings (perhaps you have a file-level
override). The documentation claims C2712 error should not be
produced under /EHa.
With /EHa, SEH and C++ exceptions may be mixed, but not in the same
function. Separate the __try block body into a separate function.