Merge pull request #4417 from Turbo87/mono

DebugBinds/Query: Reduce monomorphization overhead

diesel/src/query_builder/debug_query.rs

@@ -27,73 +27,93 @@ impl<'a, T, DB> DebugQuery<'a, T, DB> {
     }
 }
 
-impl<'a, T, DB> Display for DebugQuery<'a, T, DB>
+fn serialize_query<DB>(query: &dyn QueryFragment<DB>) -> Result<String, fmt::Error>
+where
+    DB: Backend + Default,
+    DB::QueryBuilder: Default,
+{
+    let mut query_builder = DB::QueryBuilder::default();
+    let backend = DB::default();
+    QueryFragment::<DB>::to_sql(query, &mut query_builder, &backend).map_err(|_| fmt::Error)?;
+    Ok(query_builder.finish())
+}
+
+fn display<DB>(query: &dyn QueryFragment<DB>, f: &mut fmt::Formatter<'_>) -> fmt::Result
+where
+    DB: Backend + Default,
+    DB::QueryBuilder: Default,
+{
+    let debug_binds = DebugBinds::<DB>::new(query);
+    let query = serialize_query(query)?;
+    write!(f, "{} -- binds: {:?}", query, debug_binds)
+}
+
+fn debug<DB>(query: &dyn QueryFragment<DB>, f: &mut fmt::Formatter<'_>) -> fmt::Result
+where
+    DB: Backend + Default,
+    DB::QueryBuilder: Default,
+{
+    let debug_binds = DebugBinds::<DB>::new(query);
+    let query = serialize_query(query)?;
+    f.debug_struct("Query")
+        .field("sql", &query)
+        .field("binds", &debug_binds)
+        .finish()
+}
+
+impl<T, DB> Display for DebugQuery<'_, T, DB>
 where
     DB: Backend + Default,
     DB::QueryBuilder: Default,
     T: QueryFragment<DB>,
 {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        let mut query_builder = DB::QueryBuilder::default();
-        let backend = DB::default();
-        QueryFragment::<DB>::to_sql(self.query, &mut query_builder, &backend)
-            .map_err(|_| fmt::Error)?;
-        let debug_binds = DebugBinds::<_, DB>::new(self.query);
-        write!(f, "{} -- binds: {:?}", query_builder.finish(), debug_binds)
+        display(self.query, f)
     }
 }
 
-impl<'a, T, DB> Debug for DebugQuery<'a, T, DB>
+impl<T, DB> Debug for DebugQuery<'_, T, DB>
 where
     DB: Backend + Default,
     DB::QueryBuilder: Default,
     T: QueryFragment<DB>,
 {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        let mut query_builder = DB::QueryBuilder::default();
-        let backend = DB::default();
-        QueryFragment::<DB>::to_sql(self.query, &mut query_builder, &backend)
-            .map_err(|_| fmt::Error)?;
-        let debug_binds = DebugBinds::<_, DB>::new(self.query);
-        f.debug_struct("Query")
-            .field("sql", &query_builder.finish())
-            .field("binds", &debug_binds)
-            .finish()
+        debug(self.query, f)
     }
 }
 
 /// A struct that implements `fmt::Debug` by walking the given AST and writing
 /// the `fmt::Debug` implementation of each bind parameter.
-pub(crate) struct DebugBinds<'a, T: 'a, DB> {
-    query: &'a T,
-    _marker: PhantomData<DB>,
+pub(crate) struct DebugBinds<'a, DB> {
+    query: &'a dyn QueryFragment<DB>,
 }
 
-impl<'a, T, DB> DebugBinds<'a, T, DB> {
-    fn new(query: &'a T) -> Self {
-        DebugBinds {
-            query,
-            _marker: PhantomData,
-        }
+impl<'a, DB> DebugBinds<'a, DB>
+where
+    DB: Backend,
+{
+    fn new(query: &'a dyn QueryFragment<DB>) -> Self {
+        DebugBinds { query }
     }
 }
 
-impl<'a, T, DB> Debug for DebugBinds<'a, T, DB>
+impl<DB> Debug for DebugBinds<'_, DB>
 where
     DB: Backend + Default,
-    T: QueryFragment<DB>,
 {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         let backend = DB::default();
         let mut buffer = Vec::new();
         let ast_pass = AstPass::debug_binds(&mut buffer, &backend);
         self.query.walk_ast(ast_pass).map_err(|_| fmt::Error)?;
+        format_list(f, &buffer)
+    }
+}
 
-        let mut list = f.debug_list();
-        for entry in buffer {
-            list.entry(&entry);
-        }
-        list.finish()?;
-        Ok(())
+fn format_list<'b>(f: &mut fmt::Formatter<'_>, entries: &[Box<dyn Debug + 'b>]) -> fmt::Result {
+    let mut list = f.debug_list();
+    for entry in entries {
+        list.entry(entry);
     }
 }