Remove the QueryFragment constraints from Table

This is because `QueryFragment` is going to become generic over the
backend, and I don't want to make `Table` become generic over the
backend.

Author: sgrif

diesel/src/query_builder/insert_statement.rs

@@ -54,9 +54,9 @@ impl<T, U> QueryFragment for InsertStatement<T, U> where
 
 impl<T, U> AsQuery for InsertStatement<T, U> where
     T: Table,
-    InsertStatement<T, U>: QueryFragment,
+    InsertQuery<T::AllColumns, InsertStatement<T, U>>: Query,
 {
-    type SqlType = <T::AllColumns as Expression>::SqlType;
+    type SqlType = <Self::Query as Query>::SqlType;
     type Query = InsertQuery<T::AllColumns, InsertStatement<T, U>>;
 
     fn as_query(self) -> Self::Query {

diesel/src/query_builder/select_statement/mod.rs

@@ -71,7 +71,6 @@ impl<ST, S, F> SelectStatement<ST, S, F> {
 impl<ST, S, F, W, O, L, Of> Query for SelectStatement<ST, S, F, W, O, L, Of> where
     ST: NativeSqlType,
     S: SelectableExpression<F, ST>,
-    SelectStatement<ST, S, F, W, O, L, Of>: QueryFragment
 {
     type SqlType = ST;
 }

diesel/src/query_builder/update_statement/mod.rs

@@ -74,6 +74,7 @@ pub struct UpdateQuery<T, U>(UpdateStatement<T, U>);
 
 impl<T, U> QueryFragment for UpdateQuery<T, U> where
     T: UpdateTarget,
+    <T::Table as Table>::AllColumns: QueryFragment,
     UpdateStatement<T, U>: QueryFragment,
 {
     fn to_sql(&self, out: &mut QueryBuilder) -> BuildQueryResult {
@@ -87,7 +88,6 @@ impl<T, U> QueryFragment for UpdateQuery<T, U> where
 }
 
 impl<T, U> Query for UpdateQuery<T, U> where
-    UpdateQuery<T, U>: QueryFragment,
     T: UpdateTarget,
 {
     type SqlType = <<T::Table as Table>::AllColumns as Expression>::SqlType;

diesel/src/query_source/mod.rs

@@ -41,8 +41,8 @@ pub trait Column: Expression {
 /// A SQL database table. Types which implement this trait should have been
 /// generated by the [`table!` macro](../macro.table!.html).
 pub trait Table: QuerySource + AsQuery + Sized {
-    type PrimaryKey: Column<Table=Self> + Expression + NonAggregate + QueryFragment;
-    type AllColumns: SelectableExpression<Self> + QueryFragment;
+    type PrimaryKey: Column<Table=Self> + Expression + NonAggregate;
+    type AllColumns: SelectableExpression<Self>;
 
     fn name() -> &'static str;
     fn primary_key(&self) -> Self::PrimaryKey;