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Re: Make copyObject work in C++

Peter Eisentraut <peter@eisentraut.org>

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From: Peter Eisentraut <peter@eisentraut.org>
To: Jelte Fennema-Nio <postgres@jeltef.nl>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Thomas Munro <thomas.munro@gmail.com>
Date: 2026-02-19T08:31:45Z
Lists: pgsql-hackers 
On 13.02.26 11:28, Jelte Fennema-Nio wrote:
> 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 found this paper

https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2927.htm

which led to the addition of typeof into the C standard.

It contains a section 'Why not "decltype"?' that explains how decltype 
is different, but it also explains that if typeof were added to C++, 
then it would be

     std::remove_reference_t<decltype(T)>

What I suggest we should do here is:

1. Add a configure test that checks if the C++ compiler supports typeof.

2. If not, #define typeof to the above expression.

Then code can continue to use typeof unchanged.

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