Merge pull request #216 from Ace4896/must-use-types

Mark several types as #[must_use]

sqlx-core/src/cursor.rs

@@ -39,6 +39,7 @@ use crate::row::HasRow;
 ///
 /// [`Executor::fetch`]: crate::executor::Executor::fetch
 /// [`Query::fetch`]: crate::query::Query::fetch
+#[must_use = "cursor must have `.next()` called to execute query"]
 pub trait Cursor<'c, 'q>
 where
     Self: Send + Unpin + private::Sealed,

sqlx-core/src/query.rs

@@ -14,6 +14,7 @@ use crate::row::HasRow;
 use crate::types::Type;
 
 /// Raw SQL query with bind parameters. Returned by [`query`][crate::query::query].
+#[must_use = "query must be executed to affect database"]
 pub struct Query<'q, DB>
 where
     DB: Database,
@@ -31,6 +32,7 @@ where
 ///
 /// [Query::bind] is also omitted; stylistically we recommend placing your `.bind()` calls
 /// before `.try_map()` anyway.
+#[must_use = "query must be executed to affect database"]
 pub struct Map<'q, DB, F>
 where
     DB: Database,

sqlx-core/src/query_as.rs

@@ -9,6 +9,7 @@ use crate::types::Type;
 /// Raw SQL query with bind parameters, mapped to a concrete type
 /// using [`FromRow`](trait.FromRow.html). Returned
 /// by [`query_as`](fn.query_as.html).
+#[must_use = "query must be executed to affect database"]
 pub struct QueryAs<'q, DB, O>
 where
     DB: Database,

sqlx-core/src/transaction.rs

@@ -33,6 +33,7 @@ use crate::runtime::spawn;
 /// [`rollback`]: #method.rollback
 // Transaction<PoolConnection<PgConnection>>
 // Transaction<PgConnection>
+#[must_use = "transaction rolls back if not explicitly `.commit()`ed"]
 pub struct Transaction<C>
 where
     C: Connection,