Re: PostgreSQL does not compile on macOS SDK 15.0

Hi,

> IMO the right way to test PostgreSQL against the recent beta version
> of MacOS SDK would be replacing (via a symlink perhaps) the SDK
> provided by the "Command Line Tools for Xcode" package
> (/Library/Developer/CommandLineTools/SDKs/). Or alternatively finding
> the official way of installing the beta version of this package.

As it turned out there is Command_Line_Tools_for_Xcode_16_beta.dmg
package available. It can be downloaded from
https://developer.apple.com/ after logging it. I installed it and also
did:

```
cd /Library/Developer/CommandLineTools/SDKs
sudo mkdir __ignore__
sudo mv MacOSX14.* __ignore__
```

... to make sure Postgres will not find the older version of SDK (it
did until I made this step).

Now I get the following output from `meson --setup ...`:

```
The Meson build system
Version: 0.61.2
Source dir: /Users/eax/projects/c/postgresql
Build dir: /Users/eax/projects/c/postgresql/build
Build type: native build
Project name: postgresql
Project version: 17beta2
C compiler for the host machine: cc (clang 16.0.0 "Apple clang version
16.0.0 (clang-1600.0.20.10)")
C linker for the host machine: cc ld64 1115.5.3
Host machine cpu family: x86_64
Host machine cpu: x86_64
Run-time dependency threads found: YES
Message: darwin sysroot: /Library/Developer/CommandLineTools/SDKs/MacOSX15.0.sdk
...
```

... and get the error reported by Stan. Also I can confirm that the
proposed workaround fixes it. Attached is the result of `git
format-patch` for convenience.

Personally I'm not extremely happy with this workaround though. An
alternative solution would be adding the "pg_" prefix to our type
declarations.

Another question is whether we should fix this while the SDK is in
beta or only after it is released.

Thoughts?

I added the patch to the nearest commitfest so that it wouldn't be lost [1].

[1]: https://commitfest.postgresql.org/48/5073/

-- 
Best regards,
Aleksander Alekseev