[PATCH] meson: Update meson to enable building postgres as a subproject

Hi,

On 2025-08-30 04:18:05 +0000, Elliot Haisley wrote:

While working on another project which needed libpq, I tried building postgres
as a subproject to consume a recent version of libpq, and noticed it failed.
I've put together a small patch that updates build files to not use
the global source root, which allows postgres to be built as a meson subproject.

That makes sense. I however can't apply it just now, the PG 18 code is frozen
until mid of the next week due to the release of 18rc1, and I think this
should be backpatched.

Greetings,

Andres Freund

On Sat Aug 30, 2025 at 9:55 AM CDT, Andres Freund wrote:

Hi,

On 2025-08-30 04:18:05 +0000, Elliot Haisley wrote:

While working on another project which needed libpq, I tried building postgres
as a subproject to consume a recent version of libpq, and noticed it failed.
I've put together a small patch that updates build files to not use
the global source root, which allows postgres to be built as a meson subproject.

That makes sense. I however can't apply it just now, the PG 18 code is frozen
until mid of the next week due to the release of 18rc1, and I think this
should be backpatched.

I also was working on a project that wanted to use libpq as a subproject
and came up with this independent but similar patch. I chose to develop
it against master.

I think that if we aim to support this workflow that we should add
a test in the tree somewhere. I am happy to develop one if someone
can direct me to a place where they would like it to live. In theory,
the test could even live as a meson test() in the source tree.

--
Tristan Partin
Databricks (https://databricks.com)

I also made a similar patch here /messages/by-id/F28283CF-AC9C-4930-9D84-56CD9E105504@gmail.com. I pretty much did the same thing but I also added postgres_inc to dependency because it cannot find postgres headers inside libpq’s headers. After looking at your patch i have few questions. Is meson.override_dependency(‘libpq’, libpq) really needed? It looks like it does nothing. In flex cmd args you removed —build-dir and —source-dir, was that necessary?
Also when I was testing ur patch I couldn’t build libpq because of the problem with include directories of dependency that I mentioned. I attach the result patch with fix which only adds postgres_inc to libpq dependency include_directories to your patch.

On Mon Jan 5, 2026 at 5:50 PM CST, Niyaz Hazigaleyev wrote:

I also made a similar patch here
/messages/by-id/F28283CF-AC9C-4930-9D84-56CD9E105504@gmail.com.
I pretty much did the same thing but I also added postgres_inc to
dependency because it cannot find postgres headers inside libpq’s
headers. After looking at your patch i have few questions. Is
meson.override_dependency(‘libpq’, libpq) really needed? It looks like
it does nothing. In flex cmd args you removed —build-dir and
—source-dir, was that necessary? Also when I was testing ur patch
I couldn’t build libpq because of the problem with include directories
of dependency that I mentioned. I attach the result patch with fix
which only adds postgres_inc to libpq dependency include_directories
to your patch.

I didn't have any problems with include directories, but it's possible
that my system corrupted my tests, as in my system includes supplemented
the missing subproject includes.

I removed the args from pgflex because they aren't used.

--
Tristan Partin
Databricks (https://databricks.com)