From 672b0e4505a578360741c082e7448755fdaf9265 Mon Sep 17 00:00:00 2001
From: Henry Zimmerman <hgzimmerman@users.noreply.github.com>
Date: Mon, 23 Oct 2023 16:10:47 -0400
Subject: [PATCH] Enable feature flag for SupportsCombinationClause for
 postgres_backend

I found that I couldn't compile queries that contained union and union_all expressions with the `postgres` feature flag turned replaced with `postgres_backend` while switching to `diesel-async`.
I believe that this is a simple change to allow use of the `CombineDSL` trait with just the `postgres_backend` feature.
---
 diesel/src/query_builder/combination_clause.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/diesel/src/query_builder/combination_clause.rs b/diesel/src/query_builder/combination_clause.rs
index af006dfcbfc0..cb4b6240403c 100644
--- a/diesel/src/query_builder/combination_clause.rs
+++ b/diesel/src/query_builder/combination_clause.rs
@@ -234,7 +234,7 @@ pub trait SupportsCombinationClause<Combinator, Rule> {}
 /// Wrapper used to wrap rhs sql in parenthesis when supported by backend
 pub struct ParenthesisWrapper<T>(T);
 
-#[cfg(feature = "postgres")]
+#[cfg(feature = "postgres_backend")]
 mod postgres {
     use super::*;
     use crate::pg::Pg;