meson: Improve/fix Python version selection

When we look for the Python installation using the meson python
module, we should make it use the python program previously determined
by the 'PYTHON' option.  Otherwise, it will just use its own search
and the 'PYTHON' option won't affect it.  We need this to be able to
select the Python installation to build PL/Python against.

Reviewed-by: Andres Freund <andres@anarazel.de>
Discussion: https://www.postgresql.org/message-id/flat/3f5427e8-cef6-474d-ae88-13db1bfdc1a7%40eisentraut.org

diff --git a/meson.build b/meson.build
index 96fc2e139afc9c629cabf0f127d6b7184febce30..80d8aa472857f7ce1aad38217284bbfd5967b0b4 100644 (file)
--- a/meson.build
+++ b/meson.build
@@ -1055,7 +1055,7 @@ pyopt = get_option('plpython')
 python3_dep = not_found_dep
 if not pyopt.disabled()
   pm = import('python')
-  python3_inst = pm.find_installation(required: pyopt)
+  python3_inst = pm.find_installation(python.path(), required: pyopt)
   if python3_inst.found()
     python3_dep = python3_inst.dependency(embed: true, required: pyopt)
     # Remove this check after we depend on Meson >= 1.1.0