Fix diesel-rs#3872

This commit changes some `QueryFragment` impls that previously assumed
that the provided primary key consist only of a single column. The new
implementation allows composite keys as well. In addition I also added
two tests to cover these cases as well.

diesel/src/mysql/query_builder/query_fragment_impls.rs

@@ -76,17 +76,11 @@ impl<T> QueryFragment<Mysql, crate::mysql::backend::MysqlOnConflictClause> for D
 where
     T: Table + StaticQueryFragment,
     T::Component: QueryFragment<Mysql>,
-    T::PrimaryKey: Column,
+    T::PrimaryKey: DoNothingHelper,
 {
     fn walk_ast<'b>(&'b self, mut out: AstPass<'_, 'b, Mysql>) -> QueryResult<()> {
         out.push_sql(" UPDATE ");
-        T::STATIC_COMPONENT.walk_ast(out.reborrow())?;
-        out.push_sql(".");
-        out.push_identifier(<T::PrimaryKey as Column>::NAME)?;
-        out.push_sql(" = ");
-        T::STATIC_COMPONENT.walk_ast(out.reborrow())?;
-        out.push_sql(".");
-        out.push_identifier(<T::PrimaryKey as Column>::NAME)?;
+        T::PrimaryKey::walk_ast::<T>(out.reborrow())?;
         Ok(())
     }
 }
@@ -95,20 +89,14 @@ impl<T, Tab> QueryFragment<Mysql, crate::mysql::backend::MysqlOnConflictClause>
 where
     T: QueryFragment<Mysql>,
     Tab: Table + StaticQueryFragment,
+    Tab::PrimaryKey: DoNothingHelper,
     Tab::Component: QueryFragment<Mysql>,
-    Tab::PrimaryKey: Column,
 {
     fn walk_ast<'b>(&'b self, mut out: AstPass<'_, 'b, Mysql>) -> QueryResult<()> {
         out.unsafe_to_cache_prepared();
         out.push_sql(" UPDATE ");
         if self.changeset.is_noop(out.backend())? {
-            Tab::STATIC_COMPONENT.walk_ast(out.reborrow())?;
-            out.push_sql(".");
-            out.push_identifier(<Tab::PrimaryKey as Column>::NAME)?;
-            out.push_sql(" = ");
-            Tab::STATIC_COMPONENT.walk_ast(out.reborrow())?;
-            out.push_sql(".");
-            out.push_identifier(<Tab::PrimaryKey as Column>::NAME)?;
+            Tab::PrimaryKey::walk_ast::<Tab>(out.reborrow())?;
         } else {
             self.changeset.walk_ast(out.reborrow())?;
         }
@@ -159,3 +147,70 @@ where
         self.0.walk_ast(out)
     }
 }
+
+trait DoNothingHelper {
+    fn walk_ast<'b, T>(out: AstPass<'_, 'b, Mysql>) -> QueryResult<()>
+    where
+        T: StaticQueryFragment,
+        T::Component: QueryFragment<Mysql>;
+}
+
+impl<C> DoNothingHelper for C
+where
+    C: Column,
+{
+    fn walk_ast<'b, T>(mut out: AstPass<'_, 'b, Mysql>) -> QueryResult<()>
+    where
+        T: StaticQueryFragment,
+        T::Component: QueryFragment<Mysql>,
+    {
+        T::STATIC_COMPONENT.walk_ast(out.reborrow())?;
+        out.push_sql(".");
+        out.push_identifier(C::NAME)?;
+        out.push_sql(" = ");
+        T::STATIC_COMPONENT.walk_ast(out.reborrow())?;
+        out.push_sql(".");
+        out.push_identifier(C::NAME)?;
+        Ok(())
+    }
+}
+
+macro_rules! do_nothing_for_composite_keys {
+    ($(
+        $Tuple:tt {
+            $(($idx:tt) -> $T:ident, $ST:ident, $TT:ident,)+
+        }
+    )+) => {
+        $(
+            impl<$($T,)*> DoNothingHelper for ($($T,)*)
+            where $($T: Column,)*
+            {
+                fn walk_ast<'b, Table>(mut out: AstPass<'_, 'b, Mysql>) -> QueryResult<()>
+                where
+                    Table: StaticQueryFragment,
+                    Table::Component: QueryFragment<Mysql>,
+                {
+                    let mut first = true;
+                    $(
+                        #[allow(unused_assignments)]
+                        if first {
+                            first = false;
+                        } else {
+                            out.push_sql(", ");
+                        }
+                        Table::STATIC_COMPONENT.walk_ast(out.reborrow())?;
+                        out.push_sql(".");
+                        out.push_identifier($T::NAME)?;
+                        out.push_sql(" = ");
+                        Table::STATIC_COMPONENT.walk_ast(out.reborrow())?;
+                        out.push_sql(".");
+                        out.push_identifier($T::NAME)?;
+                    )*
+                    Ok(())
+                }
+            }
+        )*
+    }
+}
+
+diesel_derives::__diesel_for_each_tuple!(do_nothing_for_composite_keys);

diesel_tests/tests/insert.rs

@@ -865,3 +865,69 @@ fn mixed_defaultable_insert() {
 
     assert_eq!(Ok(expected_data), actual_data);
 }
+
+// regression test for https://github.com/diesel-rs/diesel/issues/3872
+#[test]
+fn upsert_with_composite_primary_key_do_nothing() {
+    table! {
+        users (id, name) {
+            id -> Integer,
+            name -> Text,
+            hair_color -> Nullable<Text>,
+        }
+    }
+
+    let conn = &mut connection_with_sean_and_tess_in_users_table();
+
+    diesel::insert_into(users::table)
+        .values((users::id.eq(1), users::name.eq("John")))
+        .on_conflict_do_nothing()
+        .execute(conn)
+        .unwrap();
+    let users = users::table
+        .select(users::name)
+        .load::<String>(conn)
+        .unwrap();
+
+    assert_eq!(users[0], "Sean");
+    assert_eq!(users[1], "Tess");
+}
+
+// regression test for https://github.com/diesel-rs/diesel/issues/3872
+#[test]
+fn upsert_with_composite_primary_key_do_update() {
+    table! {
+        users (id, name) {
+            id -> Integer,
+            name -> Text,
+            hair_color -> Nullable<Text>,
+        }
+    }
+
+    let conn = &mut connection_with_sean_and_tess_in_users_table();
+
+    #[cfg(feature = "mysql")]
+    diesel::insert_into(users::table)
+        .values((users::id.eq(1), users::name.eq("John")))
+        .on_conflict(diesel::dsl::DuplicatedKeys)
+        .do_update()
+        .set(users::name.eq("Jane"))
+        .execute(conn)
+        .unwrap();
+
+    #[cfg(not(feature = "mysql"))]
+    diesel::insert_into(users::table)
+        .values((users::id.eq(1), users::name.eq("John")))
+        .on_conflict(users::id)
+        .do_update()
+        .set(users::name.eq("Jane"))
+        .execute(conn)
+        .unwrap();
+    let users = users::table
+        .select(users::name)
+        .load::<String>(conn)
+        .unwrap();
+
+    assert_eq!(users[0], "Jane");
+    assert_eq!(users[1], "Tess");
+}