2 files changed, 69 insertions, 31 deletions

diff --git a/src/backend/access/common/tupdesc.c b/src/backend/access/common/tupdesc.c
index 9fec6e33865..8cff6236e19 100644
--- a/src/backend/access/common/tupdesc.c
+++ b/src/backend/access/common/tupdesc.c
@@ -57,17 +57,13 @@ ResourceOwnerForgetTupleDesc(ResourceOwner owner, TupleDesc tupdesc)
 }
 
 /*
- * populate_compact_attribute
- *		Fill in the corresponding CompactAttribute element from the
- *		Form_pg_attribute for the given attribute number.  This must be called
- *		whenever a change is made to a Form_pg_attribute in the TupleDesc.
+ * populate_compact_attribute_internal
+ *		Helper function for populate_compact_attribute()
  */
-void
-populate_compact_attribute(TupleDesc tupdesc, int attnum)
+static inline void
+populate_compact_attribute_internal(Form_pg_attribute src,
+									CompactAttribute *dst)
 {
-	Form_pg_attribute src = TupleDescAttr(tupdesc, attnum);
-	CompactAttribute *dst = &tupdesc->compact_attrs[attnum];
-
 	memset(dst, 0, sizeof(CompactAttribute));
 
 	dst->attcacheoff = -1;
@@ -102,6 +98,63 @@ populate_compact_attribute(TupleDesc tupdesc, int attnum)
 }
 
 /*
+ * populate_compact_attribute
+ *		Fill in the corresponding CompactAttribute element from the
+ *		Form_pg_attribute for the given attribute number.  This must be called
+ *		whenever a change is made to a Form_pg_attribute in the TupleDesc.
+ */
+void
+populate_compact_attribute(TupleDesc tupdesc, int attnum)
+{
+	Form_pg_attribute src = TupleDescAttr(tupdesc, attnum);
+	CompactAttribute *dst;
+
+	/*
+	 * Don't use TupleDescCompactAttr to prevent infinite recursion in assert
+	 * builds.
+	 */
+	dst = &tupdesc->compact_attrs[attnum];
+
+	populate_compact_attribute_internal(src, dst);
+}
+
+#ifdef USE_ASSERT_CHECKING
+/*
+ * verify_compact_attribute
+ *		In Assert enabled builds, we verify that the CompactAttribute is
+ *		populated correctly.  This helps find bugs in places such as ALTER
+ *		TABLE where code makes changes to the FormData_pg_attribute but
+ *		forgets to call populate_compact_attribute().
+ *
+ * This is used in TupleDescCompactAttr(), but declared here to allow access
+ * to populate_compact_attribute_internal().
+ */
+void
+verify_compact_attribute(TupleDesc tupdesc, int attnum)
+{
+	CompactAttribute *cattr = &tupdesc->compact_attrs[attnum];
+	Form_pg_attribute attr = TupleDescAttr(tupdesc, attnum);
+	CompactAttribute tmp;
+
+	/*
+	 * Populate the temporary CompactAttribute from the corresponding
+	 * Form_pg_attribute
+	 */
+	populate_compact_attribute_internal(attr, &tmp);
+
+	/*
+	 * Make the attcacheoff match since it's been reset to -1 by
+	 * populate_compact_attribute_internal.
+	 */
+	tmp.attcacheoff = cattr->attcacheoff;
+
+	/* Check the freshly populated CompactAttribute matches the TupleDesc's */
+	Assert(memcmp(&tmp, cattr, sizeof(CompactAttribute)) == 0);
+}
+#endif
+
+
+/*
  * CreateTemplateTupleDesc
  *		This function allocates an empty tuple descriptor structure.
  *
diff --git a/src/include/access/tupdesc.h b/src/include/access/tupdesc.h
index e61a4affa46..05ccd2465fc 100644
--- a/src/include/access/tupdesc.h
+++ b/src/include/access/tupdesc.h
@@ -158,6 +158,10 @@ TupleDescAttr(TupleDesc tupdesc, int i)
 
 #undef TupleDescAttrAddress
 
+#ifdef USE_ASSERT_CHECKING
+extern void verify_compact_attribute(TupleDesc, int attnum);
+#endif
+
 /*
  * Accessor for the i'th CompactAttribute element of tupdesc.
  */
@@ -165,30 +169,11 @@ static inline CompactAttribute *
 TupleDescCompactAttr(TupleDesc tupdesc, int i)
 {
 	CompactAttribute *cattr = &tupdesc->compact_attrs[i];
-#ifdef USE_ASSERT_CHECKING
-	CompactAttribute snapshot;
 
-	/*
-	 * In Assert enabled builds we verify that the CompactAttribute is
-	 * populated correctly.  This helps find bugs in places such as ALTER
-	 * TABLE where code makes changes to the FormData_pg_attribute but forgets
-	 * to call populate_compact_attribute.
-	 */
-
-	/*
-	 * Take a snapshot of how the CompactAttribute is now before calling
-	 * populate_compact_attribute to make it up-to-date with the
-	 * FormData_pg_attribute.
-	 */
-	memcpy(&snapshot, cattr, sizeof(CompactAttribute));
-
-	populate_compact_attribute(tupdesc, i);
-
-	/* reset attcacheoff back to what it was */
-	cattr->attcacheoff = snapshot.attcacheoff;
+#ifdef USE_ASSERT_CHECKING
 
-	/* Ensure the snapshot matches the freshly populated CompactAttribute */
-	Assert(memcmp(&snapshot, cattr, sizeof(CompactAttribute)) == 0);
+	/* Check that the CompactAttribute is correctly populated */
+	verify_compact_attribute(tupdesc, i);
 #endif
 
 	return cattr;