From: Niyaz Hazigaleyev <hazigaleevniaz@gmail.com>
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Subject: Use Postgres as meson wrap subproject
Message-Id: <F28283CF-AC9C-4930-9D84-56CD9E105504@gmail.com>
Date: Tue, 23 Dec 2025 18:21:16 +0300
To: pgsql-hackers@lists.postgresql.org
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 <https://www.postgresql.org/message-id/F28283CF-AC9C-4930-9D84-56CD9E105504%40gmail.com>
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It is not possible to use Postgres as meson wrap subproject at least out =
of box. But I think it can be easily fixed. I made a small patch for =
libpq and it works. There were two problems, first is catalog header =
generator using @SOURCE_DIR@ as root for paths, which will use main root =
project as source dir, so I just changed it to =
meson.project_source_root(). Second was that libpq dependency =
include_directories had no dependent headers(for example postgres_ext.h) =
so I just used include_directories that were also used in libpq_so, =
libpq_st. So the patch looks like this for commit =
955f5506863dce0a3416e3fae7c3297dbbaa946d:=20

diff --git a/src/include/catalog/meson.build =
b/src/include/catalog/meson.build
index ec1cf46..2b12e8e 100644
--- a/src/include/catalog/meson.build
+++ b/src/include/catalog/meson.build
@@ -136,7 +136,7 @@ generated_catalog_headers =3D =
custom_target('generated_catalog_headers',
   command: [
     perl,
     files('../../backend/catalog/genbki.pl'),
-    '--include-path=3D@SOURCE_ROOT@/src/include',
+    '--include-path=3D' + (meson.project_source_root() / =
'src/include'),
     '--set-version=3D' + pg_version_major.to_string(),
     '--output=3D@OUTDIR@', '@INPUT@'
   ],
diff --git a/src/interfaces/libpq/meson.build =
b/src/interfaces/libpq/meson.build
index b259c99..51e051f 100644
--- a/src/interfaces/libpq/meson.build
+++ b/src/interfaces/libpq/meson.build
@@ -82,7 +82,7 @@ libpq_so =3D shared_library('libpq',
=20
 libpq =3D declare_dependency(
   link_with: [libpq_so],
-  include_directories: [include_directories('.')]
+  include_directories: [libpq_inc, postgres_inc]
 )
=20
 # Check for functions that libpq must not call.  See libpq_check.pl for =
the

Example of wrap file that applies patch:

[wrap-git]
url =3D https://git.postgresql.org/git/postgresql.git
revision =3D 955f5506863dce0a3416e3fae7c3297dbbaa946d
depth =3D 1
diff_files =3D postgres/libpq.patch
[provide]
libpq =3D libpq

So to use Postgres as wrap subproject u need to change @SOURCE_DIR@ to =
meson.project_source_root() and check include_directories for all =
dependencies. Is there any plans to support it?=