On Wednesday, 9 April 2014 at 17:27:56 UTC, David Nadlinger wrote:
> On Wednesday, 9 April 2014 at 16:48:54 UTC, Jacob Carlborg wrote:
>> x86_64 yes, not necessarily only for DMD. I thought if DMD, LDC and GDC all used the same exception handling model and the same as C++ it would be easier. Especially for implementing support for Objective-C exceptions, which is why initially started this thread.
>
> They don't. GDC and LDC use libunwind, whereas DMD uses its own custom EH implementation.
>
> With GDC and LDC, you'd just need to add your code to handle Objective-C exceptions to the personality functions. libunwind exceptions have a "type"/"source language" field, and by default most implementations either ignore unknown exception types or abort on encountering them.
>
> David

The C++ personality function from GCC does not catch, but do the cleanup on foreign exceptions. That sound like the right behavior to me.

On 2014-04-10 08:53, deadalnix wrote:

> The C++ personality function from GCC does not catch, but do the cleanup
> on foreign exceptions. That sound like the right behavior to me.

As far as I understand the cleaning is only a part of what personality function does. The first thing it does is check if the thrown exception can be handled. Like determine if it's a C++ exception or some other exception. If I recall correctly, it also determines if and where to resume unwinding, where to find catch blocks and so on.

This [1] series of blog posts gives a pretty good understanding of how C++ exceptions work under the hood, for those that don't want to read the ABI documentation.

[1] http://monoinfinito.wordpress.com/series/exception-handling-in-c/

-- 
/Jacob Carlborg

On Thursday, 10 April 2014 at 19:23:12 UTC, Jacob Carlborg wrote:
> On 2014-04-10 08:53, deadalnix wrote:
>
>> The C++ personality function from GCC does not catch, but do the cleanup
>> on foreign exceptions. That sound like the right behavior to me.
>
> As far as I understand the cleaning is only a part of what personality function does. The first thing it does is check if the thrown exception can be handled. Like determine if it's a C++ exception or some other exception. If I recall correctly, it also determines if and where to resume unwinding, where to find catch blocks and so on.
>
> This [1] series of blog posts gives a pretty good understanding of how C++ exceptions work under the hood, for those that don't want to read the ABI documentation.
>
> [1] http://monoinfinito.wordpress.com/series/exception-handling-in-c/

You want to look at libstdc++-v3/libsupc++/eh_personality.cc in gcc's source code.

The personality function test if the exception is a C++ exception, in which case the regular flow apply. If not, the foreign_exception flag is set, and some behavior are altered. Basically, for what we are concerned with D, only cleanup will be executed (the filter part is irrelevant to D).

On 11/04/14 00:05, deadalnix wrote:

> You want to look at libstdc++-v3/libsupc++/eh_personality.cc in gcc's
> source code.

If I'm to look at some source code I rather look at libc++abi from LLVM.

> The personality function test if the exception is a C++ exception, in
> which case the regular flow apply. If not, the foreign_exception flag is
> set, and some behavior are altered. Basically, for what we are concerned
> with D, only cleanup will be executed (the filter part is irrelevant to D).

Why is the filter part irrelevant?

-- 
/Jacob Carlborg

On Friday, 11 April 2014 at 06:29:37 UTC, Jacob Carlborg wrote:
> Why is the filter part irrelevant?

filter is "catch everything but.." kind of clause. The semantic do not exists in D, so we don't really care.