Fix dumping of comments on invalid constraints on domains

We skip dumping constraints together with domains if they are invalid
('separate') so that they appear after data -- but their comments were
dumped together with the domain definition, which in effect leads to the
comment being dumped when the constraint does not yet exist.  Delay
them in the same way.

Oversight in 7eca575d1c28; backpatch all the way back.

Author: jian he <jian.universality@gmail.com>
Discussion: https://postgr.es/m/CACJufxF_C2pe6J_+nPr6C5jf5rQnbYP8XOKr4HM8yHZtp2aQqQ@mail.gmail.com

src/bin/pg_dump/pg_dump.c

@@ -11638,8 +11638,13 @@ dumpDomain(Archive *fout, const TypeInfo *tyinfo)
 	for (i = 0; i < tyinfo->nDomChecks; i++)
 	{
 		ConstraintInfo *domcheck = &(tyinfo->domChecks[i]);
-		PQExpBuffer conprefix = createPQExpBuffer();
+		PQExpBuffer conprefix;
 
+		/* but only if the constraint itself was dumped here */
+		if (domcheck->separate)
+			continue;
+
+		conprefix = createPQExpBuffer();
 		appendPQExpBuffer(conprefix, "CONSTRAINT %s ON DOMAIN",
 						  fmtId(domcheck->dobj.name));
 
@@ -17495,6 +17500,22 @@ dumpConstraint(Archive *fout, const ConstraintInfo *coninfo)
 										  .section = SECTION_POST_DATA,
 										  .createStmt = q->data,
 										  .dropStmt = delq->data));
+
+			if (coninfo->dobj.dump & DUMP_COMPONENT_COMMENT)
+			{
+				PQExpBuffer conprefix = createPQExpBuffer();
+				char	   *qtypname = pg_strdup(fmtId(tyinfo->dobj.name));
+
+				appendPQExpBuffer(conprefix, "CONSTRAINT %s ON DOMAIN",
+								  fmtId(coninfo->dobj.name));
+
+				dumpComment(fout, conprefix->data, qtypname,
+							tyinfo->dobj.namespace->dobj.name,
+							tyinfo->rolname,
+							coninfo->dobj.catId, 0, tyinfo->dobj.dumpId);
+				destroyPQExpBuffer(conprefix);
+				free(qtypname);
+			}
 		}
 	}
 	else

src/test/regress/input/constraints.source

@@ -612,3 +612,9 @@ DROP DOMAIN constraint_comments_dom;
 
 DROP ROLE regress_constraint_comments;
 DROP ROLE regress_constraint_comments_noaccess;
+
+-- Leave some constraints for the pg_upgrade test to pick up
+CREATE DOMAIN constraint_comments_dom AS int;
+
+ALTER DOMAIN constraint_comments_dom ADD CONSTRAINT inv_ck CHECK (value > 0) NOT VALID;
+COMMENT ON CONSTRAINT inv_ck ON DOMAIN constraint_comments_dom IS 'comment on invalid constraint';

src/test/regress/output/constraints.source

@@ -802,3 +802,7 @@ DROP TABLE constraint_comments_tbl;
 DROP DOMAIN constraint_comments_dom;
 DROP ROLE regress_constraint_comments;
 DROP ROLE regress_constraint_comments_noaccess;
+-- Leave some constraints for the pg_upgrade test to pick up
+CREATE DOMAIN constraint_comments_dom AS int;
+ALTER DOMAIN constraint_comments_dom ADD CONSTRAINT inv_ck CHECK (value > 0) NOT VALID;
+COMMENT ON CONSTRAINT inv_ck ON DOMAIN constraint_comments_dom IS 'comment on invalid constraint';