Remove circular #include's between plpython.h and plpy_util.h.

plpython.h included plpy_util.h, simply on the grounds that "it's
easier to just include it everywhere".  However, plpy_util.h must
include plpython.h, or it won't pass headerscheck.  While the
resulting circularity doesn't have any immediate bad effect,
it's poor design.  We have seen serious messes arise in the past
from overly-broad inclusion footprints created by such circularities,
so let's establish a project policy against it.

To fix, just replace *.c files' inclusions of plpython.h with
plpy_util.h.  They'll pull in plpython.h indirectly; indeed, almost
all have already done so via inclusions of other plpy_xxx.h headers.
(Any extensions using plpython.h can do likewise without breaking
the compatibility of their code with prior Postgres versions.)

Reported-by: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Author: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Discussion: https://postgr.es/m/aAxQ6fcY5QQV1lo3@ip-10-97-1-34.eu-west-3.compute.internal

16 files changed, 18 insertions, 20 deletions

diff --git a/contrib/hstore_plpython/hstore_plpython.c b/contrib/hstore_plpython/hstore_plpython.c
index 8812fb3f3e4..e2bfc6da38e 100644
--- a/contrib/hstore_plpython/hstore_plpython.c
+++ b/contrib/hstore_plpython/hstore_plpython.c
@@ -3,7 +3,7 @@
 #include "fmgr.h"
 #include "hstore/hstore.h"
 #include "plpy_typeio.h"
-#include "plpython.h"
+#include "plpy_util.h"
 
 PG_MODULE_MAGIC_EXT(
 					.name = "hstore_plpython",
diff --git a/contrib/jsonb_plpython/jsonb_plpython.c b/contrib/jsonb_plpython/jsonb_plpython.c
index 680445a006f..9383615abbf 100644
--- a/contrib/jsonb_plpython/jsonb_plpython.c
+++ b/contrib/jsonb_plpython/jsonb_plpython.c
@@ -2,7 +2,7 @@
 
 #include "plpy_elog.h"
 #include "plpy_typeio.h"
-#include "plpython.h"
+#include "plpy_util.h"
 #include "utils/fmgrprotos.h"
 #include "utils/jsonb.h"
 #include "utils/numeric.h"
diff --git a/contrib/ltree_plpython/ltree_plpython.c b/contrib/ltree_plpython/ltree_plpython.c
index ba5926b8be6..0493aeb2423 100644
--- a/contrib/ltree_plpython/ltree_plpython.c
+++ b/contrib/ltree_plpython/ltree_plpython.c
@@ -2,7 +2,7 @@
 
 #include "fmgr.h"
 #include "ltree/ltree.h"
-#include "plpython.h"
+#include "plpy_util.h"
 
 PG_MODULE_MAGIC_EXT(
 					.name = "ltree_plpython",
diff --git a/src/pl/plpython/plpy_cursorobject.c b/src/pl/plpython/plpy_cursorobject.c
index 1c6be756120..37d7efca77c 100644
--- a/src/pl/plpython/plpy_cursorobject.c
+++ b/src/pl/plpython/plpy_cursorobject.c
@@ -16,7 +16,7 @@
 #include "plpy_planobject.h"
 #include "plpy_resultobject.h"
 #include "plpy_spi.h"
-#include "plpython.h"
+#include "plpy_util.h"
 #include "utils/memutils.h"
 
 static PyObject *PLy_cursor_query(const char *query);
diff --git a/src/pl/plpython/plpy_elog.c b/src/pl/plpython/plpy_elog.c
index 70de5ba13d7..ddf3573f0e7 100644
--- a/src/pl/plpython/plpy_elog.c
+++ b/src/pl/plpython/plpy_elog.c
@@ -10,7 +10,7 @@
 #include "plpy_elog.h"
 #include "plpy_main.h"
 #include "plpy_procedure.h"
-#include "plpython.h"
+#include "plpy_util.h"
 
 PyObject   *PLy_exc_error = NULL;
 PyObject   *PLy_exc_fatal = NULL;
diff --git a/src/pl/plpython/plpy_exec.c b/src/pl/plpython/plpy_exec.c
index 00747bb811b..28fbd443b98 100644
--- a/src/pl/plpython/plpy_exec.c
+++ b/src/pl/plpython/plpy_exec.c
@@ -17,7 +17,7 @@
 #include "plpy_main.h"
 #include "plpy_procedure.h"
 #include "plpy_subxactobject.h"
-#include "plpython.h"
+#include "plpy_util.h"
 #include "utils/fmgrprotos.h"
 #include "utils/rel.h"
 
diff --git a/src/pl/plpython/plpy_main.c b/src/pl/plpython/plpy_main.c
index 8f56155f006..f36eadbadc6 100644
--- a/src/pl/plpython/plpy_main.c
+++ b/src/pl/plpython/plpy_main.c
@@ -18,7 +18,7 @@
 #include "plpy_plpymodule.h"
 #include "plpy_procedure.h"
 #include "plpy_subxactobject.h"
-#include "plpython.h"
+#include "plpy_util.h"
 #include "utils/guc.h"
 #include "utils/memutils.h"
 #include "utils/rel.h"
diff --git a/src/pl/plpython/plpy_planobject.c b/src/pl/plpython/plpy_planobject.c
index 3e385555e5e..6044893afdd 100644
--- a/src/pl/plpython/plpy_planobject.c
+++ b/src/pl/plpython/plpy_planobject.c
@@ -9,7 +9,7 @@
 #include "plpy_cursorobject.h"
 #include "plpy_planobject.h"
 #include "plpy_spi.h"
-#include "plpython.h"
+#include "plpy_util.h"
 #include "utils/memutils.h"
 
 static void PLy_plan_dealloc(PLyPlanObject *self);
diff --git a/src/pl/plpython/plpy_plpymodule.c b/src/pl/plpython/plpy_plpymodule.c
index ea06d9a52b1..1f980b44b2a 100644
--- a/src/pl/plpython/plpy_plpymodule.c
+++ b/src/pl/plpython/plpy_plpymodule.c
@@ -14,7 +14,7 @@
 #include "plpy_resultobject.h"
 #include "plpy_spi.h"
 #include "plpy_subxactobject.h"
-#include "plpython.h"
+#include "plpy_util.h"
 #include "utils/builtins.h"
 
 HTAB	   *PLy_spi_exceptions = NULL;
diff --git a/src/pl/plpython/plpy_procedure.c b/src/pl/plpython/plpy_procedure.c
index b494eeb474f..c176d24e801 100644
--- a/src/pl/plpython/plpy_procedure.c
+++ b/src/pl/plpython/plpy_procedure.c
@@ -13,7 +13,7 @@
 #include "plpy_elog.h"
 #include "plpy_main.h"
 #include "plpy_procedure.h"
-#include "plpython.h"
+#include "plpy_util.h"
 #include "utils/builtins.h"
 #include "utils/hsearch.h"
 #include "utils/memutils.h"
diff --git a/src/pl/plpython/plpy_resultobject.c b/src/pl/plpython/plpy_resultobject.c
index 80fa1d7accc..0d9997cbaa3 100644
--- a/src/pl/plpython/plpy_resultobject.c
+++ b/src/pl/plpython/plpy_resultobject.c
@@ -8,7 +8,7 @@
 
 #include "plpy_elog.h"
 #include "plpy_resultobject.h"
-#include "plpython.h"
+#include "plpy_util.h"
 
 static void PLy_result_dealloc(PLyResultObject *self);
 static PyObject *PLy_result_colnames(PyObject *self, PyObject *unused);
diff --git a/src/pl/plpython/plpy_spi.c b/src/pl/plpython/plpy_spi.c
index 77fbfd6c868..1e386aadcca 100644
--- a/src/pl/plpython/plpy_spi.c
+++ b/src/pl/plpython/plpy_spi.c
@@ -19,7 +19,7 @@
 #include "plpy_plpymodule.h"
 #include "plpy_resultobject.h"
 #include "plpy_spi.h"
-#include "plpython.h"
+#include "plpy_util.h"
 #include "utils/memutils.h"
 
 static PyObject *PLy_spi_execute_query(char *query, long limit);
diff --git a/src/pl/plpython/plpy_subxactobject.c b/src/pl/plpython/plpy_subxactobject.c
index ad24a9fc4b8..c2484a99b4a 100644
--- a/src/pl/plpython/plpy_subxactobject.c
+++ b/src/pl/plpython/plpy_subxactobject.c
@@ -9,7 +9,7 @@
 #include "access/xact.h"
 #include "plpy_elog.h"
 #include "plpy_subxactobject.h"
-#include "plpython.h"
+#include "plpy_util.h"
 #include "utils/memutils.h"
 
 List	   *explicit_subtransactions = NIL;
diff --git a/src/pl/plpython/plpy_typeio.c b/src/pl/plpython/plpy_typeio.c
index 1d127ae3ffe..f6509a41902 100644
--- a/src/pl/plpython/plpy_typeio.c
+++ b/src/pl/plpython/plpy_typeio.c
@@ -14,7 +14,7 @@
 #include "plpy_elog.h"
 #include "plpy_main.h"
 #include "plpy_typeio.h"
-#include "plpython.h"
+#include "plpy_util.h"
 #include "utils/array.h"
 #include "utils/builtins.h"
 #include "utils/fmgroids.h"
diff --git a/src/pl/plpython/plpy_util.c b/src/pl/plpython/plpy_util.c
index 6d89b1cb60a..ef710aa371e 100644
--- a/src/pl/plpython/plpy_util.c
+++ b/src/pl/plpython/plpy_util.c
@@ -9,7 +9,6 @@
 #include "mb/pg_wchar.h"
 #include "plpy_elog.h"
 #include "plpy_util.h"
-#include "plpython.h"
 
 /*
  * Convert a Python unicode object to a Python string/bytes object in
diff --git a/src/pl/plpython/plpython.h b/src/pl/plpython/plpython.h
index 06fc1a5440f..118b3100840 100644
--- a/src/pl/plpython/plpython.h
+++ b/src/pl/plpython/plpython.h
@@ -2,6 +2,10 @@
  *
  * plpython.h - Python as a procedural language for PostgreSQL
  *
+ * Note: this file is #include'd by each of the sub-module header files
+ * (plpy_elog.h, etc).  It's therefore unnecessary for any plpython *.c
+ * files to include it directly.
+ *
  * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
@@ -38,9 +42,4 @@
 #undef TEXTDOMAIN
 #define TEXTDOMAIN PG_TEXTDOMAIN("plpython")
 
-/*
- * Used throughout, so it's easier to just include it everywhere.
- */
-#include "plpy_util.h"
-
 #endif							/* PLPYTHON_H */