From: Tom Lane <tgl@sss.pgh.pa.us>
To: Andres Freund <andres@anarazel.de>
cc: Peter Geoghegan <pg@heroku.com>, Robert Haas <robertmhaas@gmail.com>,
        Jim Nasby <Jim.Nasby@bluetreble.com>,
        Gavin Flower <GavinFlower@archidevsys.co.nz>, dandl <david@andl.org>,
        Adam Brusselback <adambrusselback@gmail.com>,
        Joy Arulraj <jarulraj@cs.cmu.edu>, kang joni <kangjoni76@gmail.com>,
        Dmitry Igrishin <dmitigr@gmail.com>,
        Pg Hackers <pgsql-hackers@postgresql.org>,
        Peter Eisentraut <peter_e@gmx.net>
Subject: Re: [GENERAL] C++ port of Postgres
In-reply-to: <20160816205518.yesjo6w2t6os3kvu@alap3.anarazel.de>
References: 
 <CAOmy0wLcyE3d=jbfpgoKtTicGoZ64AKKfEkG+ccXxtmajSBGeQ@mail.gmail.com>
 <CABgyVxBjX6VbnbHfZRSDJBav4xKH5vSLZqTpr989sMOb+jX+jA@mail.gmail.com>
 <CAMjNa7e7E81T3NqoReixYxrCFQpfWd+Mht0NhetW3bJB=Gs7Og@mail.gmail.com>
 <007001d1f786$d903fa90$8b0befb0$@andl.org>
 <00a52208-3199-5858-8846-2530b0bb34df@archidevsys.co.nz>
 <f7682c24-4271-1ff5-d963-053ecb0fce40@BlueTreble.com>
 <CA+Tgmoa8=kMNkOGDCZYR-L_PAoQ2Vdb9EmSV+=7pRv+J3u7_CA@mail.gmail.com>
 <27271.1471366764@sss.pgh.pa.us>
 <CAM3SWZSu+++ZvHdHst71fSKdLON5GMo-2L_Lk2mN5QvBmuBNBg@mail.gmail.com>
 <CAM3SWZRf9u8CbyOZY4W2iS3Xj_bafMHYraetSbc=W79NQKn_DA@mail.gmail.com>
 <20160816205518.yesjo6w2t6os3kvu@alap3.anarazel.de>
Comments: In-reply-to Andres Freund <andres@anarazel.de>
	message dated "Tue, 16 Aug 2016 13:55:18 -0700"
Date: Tue, 16 Aug 2016 16:59:56 -0400
Message-ID: <28200.1471381196@sss.pgh.pa.us>
Precedence: bulk
Sender: pgsql-hackers-owner@postgresql.org

Andres Freund <andres@anarazel.de> writes:
> On 2016-08-16 13:40:06 -0700, Peter Geoghegan wrote:
>> Actually, come to think of it, I guess this is wrong. The problem with
>> what I say here is that longjmp() and setjmp() are incompatible with
>> the stack unwinding used by C++ destructors in general (exceptions are
>> another issue). I think that the practical implication of that is that
>> we can never use any C++ feature that hides the complexity of resource
>> management, unless and until elog() is reimplemented to not use
>> longjmp() and setjmp().

> FWIW, IIRC that's not true for gcc/glibc, because they IIRC use common
> codepaths. But obviously that's not all-encompassing enough to rely on that.

I wonder whether it'd be possible to implement the PG_TRY/CATCH macros
to use C++ exceptions when building in C++.  This would probably mean
that C and C++ builds would be incompatible as far as loadable extensions
are concerned, because it'd amount to an ABI difference.  But maybe
that's OK.  We could certainly have the PG_MODULE_MAGIC macro guard
against the case.

			regards, tom lane


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