Message-ID: <b03ddcd4-2a16-49ee-b105-e7f609f3c514@gmail.com>
Date: Wed, 4 Feb 2026 09:54:37 -0600
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Subject: Re: Make copyObject work in C++
To: pgsql-hackers@lists.postgresql.org
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From: Bryan Green <dbryan.green@gmail.com>
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On 1/25/2026 6:42 AM, Jelte Fennema-Nio wrote:
> On Tue Jan 20, 2026 at 5:28 PM CET, Peter Eisentraut wrote:
>> I have split your first patch further.  For a start, I left out the
>> PG_MODULE_MAGIC*-related changes and disabled the module under MSVC.
>> This has been committed.  I plan to let the buildfarm run with it for
>> a day or two and then add in the basic MSVC support.
> 
> To hopefully make your life a bit easier. Here's a rebased version that
> enables the MSVC support again, with an updated commit message.
> 
This causes the build to break on VS 2022.  Versions prior do not have
support for __typeof_unqual__.  This would have led to
HAVE_TYPEOF_UNQUAL being not defined on the buildfarm causing the
fallback to copyObjectImpl() for VS 2019.

When you build on VS 2022 you will get an error:
../src/backend/commands/event_trigger.c(1901): error C2100: you cannot
dereference an operand of type 'void'

VS 2022 (MSVC) does not handle the void * dereference the way gcc/clang
does (thanks to GNU extensions, I believe).  It exposes
__typeof_unqual__ even it C11, but enforces strict C semantics on the
void * dereference.  To work on this platform the call
copyObject(lfirst(cell)) would need to have a cast to the correct
concrete type: copyObject((Node *)lfirst(cell)).

I was about to update to VS 2026, but now I think I should have an
instance of VS from 2019, 2022, and 2026.

-- 
Bryan Green
EDB: https://www.enterprisedb.com