meson: Make detection of python more robust

Previously we errored out if no python installation could be found (but we did
handle not having enough of python installed to build plpython
against). Presumably nobody hit this so far, as python is likely installed due
to meson requiring python.

Author: Tristan Partin <[email protected]>
Discussion: https://postgr.es/m/CSPIJVUDZFKX.3KHMOAVGF94RV@c3po
Backpatch: 16-, where meson support was added

diff --git a/meson.build b/meson.build
index 862c955453f4f0e16bb12854efc495ca4ab31f50..2d516c8f372a7d9550ba8dd2bfd15581fff647ac 100644 (file)
--- a/meson.build
+++ b/meson.build
@@ -1056,15 +1056,17 @@ endif
 ###############################################################
 
 pyopt = get_option('plpython')
+python3_dep = not_found_dep
 if not pyopt.disabled()
   pm = import('python')
   python3_inst = pm.find_installation(required: pyopt)
-  python3_dep = python3_inst.dependency(embed: true, required: pyopt)
-  if not cc.check_header('Python.h', dependencies: python3_dep, required: pyopt)
-    python3_dep = not_found_dep
+  if python3_inst.found()
+    python3_dep = python3_inst.dependency(embed: true, required: pyopt)
+    # Remove this check after we depend on Meson >= 1.1.0
+    if not cc.check_header('Python.h', dependencies: python3_dep, required: pyopt)
+      python3_dep = not_found_dep
+    endif
   endif
-else
-  python3_dep = not_found_dep
 endif