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Re: Make copyObject work in C++

Jelte Fennema <postgres@jeltef.nl>

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From: "Jelte Fennema-Nio" <postgres@jeltef.nl>
To: "Andres Freund" <andres@anarazel.de>
Cc: "Peter Eisentraut" <peter@eisentraut.org>, "PostgreSQL Hackers" <pgsql-hackers@lists.postgresql.org>, "Thomas Munro" <thomas.munro@gmail.com>
Date: 2026-02-13T10:28:20Z
Lists: pgsql-hackers

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On Sun Jan 25, 2026 at 9:06 PM CET, Andres Freund wrote:
> Named args make that easier in two ways: First, only extensions using the
> to-be-removed option will fail. Second, removal of options reliably generates
> errors, rather than bogusly use one field for another, just because the types
> are compatible.

After discussing the topic in-person with Peter at FOSDEM. We agreed
that the best road forward was to not bother with MSVC for now. No-one
has actually expressed an interest in being able to build C++ extension
using MSVC, and the effort to support it is both non-trivial and not
without downsides to the rest of the codebase. We can always come back
to this later, possibly requiring C++20 on MSVC.

So I've removed that patch and now this patchset its goal is to improve
compatibiltity with the C++ flavor of GCC and Clang.

Patch 1 and 2 add some more macro calls to our test C++ extension. These
macros already work in GCC and Clang, this is purely to test for future
regressinos.

Patch 3 makes copyObject work when using GCC or Clang with -std=c++11 by
introducing pg_exprtype.

Patch 4 starts using pg_exprtype in more places.

I'm also working on some patches to support
StaticAssertVariableIsOfType, but I've run into some ICE compiler errors
of MSVC 2019.

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Enable test_cplusplusext with MSVC

  2. Disable some C++ warnings in MSVC

  3. meson: Make room for C++-only warning flags for MSVC

  4. Make fixed-length list building macros work in C++

  5. Make unconstify and unvolatize use StaticAssertVariableIsOfTypeMacro

  6. Use typeof everywhere instead of compiler specific spellings

  7. Test List macros in C++ extensions

  8. Test most StaticAssert macros in C++ extensions

  9. Revert "Change copyObject() to use typeof_unqual"

  10. Fix for C++ compatibility

  11. tests: Add a test C++ extension module