Merge pull request #4011 from Ten0/auto_type_bare_select_and_into_sql

Add support of `dsl::select()` and `.into_sql()` to auto_type

Author: Ten0

diesel/src/expression/helper_types.rs

@@ -157,6 +157,9 @@ pub type Otherwise<W, E> = expression::case_when::CaseWhen<
 /// Represents the return type of [`.as_select()`](crate::prelude::SelectableHelper::as_select)
 pub type AsSelect<Source, DB> = SelectBy<Source, DB>;
 
+/// Represents the return type of [`.into_sql()`](crate::expression::IntoSql::into_sql)
+pub type IntoSql<Item, SqlType> = AsExprOf<Item, SqlType>;
+
 /// The return type of [`alias.field(field)`](crate::query_source::Alias::field)
 pub type Field<Alias, Field> = Fields<Alias, Field>;
 

diesel/src/expression/mod.rs

@@ -65,7 +65,7 @@ pub(crate) mod dsl {
     #[doc(inline)]
     pub use super::functions::date_and_time::*;
     #[doc(inline)]
-    pub use super::helper_types::{case_when, Otherwise, When};
+    pub use super::helper_types::{case_when, IntoSql, Otherwise, When};
     #[doc(inline)]
     pub use super::not::not;
     #[doc(inline)]

diesel/src/lib.rs

@@ -364,6 +364,14 @@ pub mod helper_types {
     pub type Select<Source, Selection> = <Source as SelectDsl<Selection>>::Output;
 
     /// Represents the return type of [`diesel::select(selection)`](crate::select)
+    #[allow(non_camel_case_types)] // required for `#[auto_type]`
+    pub type select<Selection> = crate::query_builder::SelectStatement<
+        crate::query_builder::NoFromClause,
+        SelectClause<Selection>,
+    >;
+
+    #[doc(hidden)]
+    #[deprecated(note = "Use `select` instead")]
     pub type BareSelect<Selection> = crate::query_builder::SelectStatement<
         crate::query_builder::NoFromClause,
         SelectClause<Selection>,
@@ -680,6 +688,11 @@ pub mod prelude {
     pub use crate::expression::{
         AppearsOnTable, BoxableExpression, Expression, IntoSql, Selectable, SelectableExpression,
     };
+    // If [`IntoSql`](crate::expression::helper_types::IntoSql) the type gets imported at the
+    // same time as IntoSql the trait (this one) gets imported via the prelude, then
+    // methods of the trait won't be resolved because the type may take priority over the trait.
+    // That issue can be avoided by also importing it anonymously:
+    pub use crate::expression::IntoSql as _;
 
     #[doc(inline)]
     pub use crate::expression::functions::define_sql_function;

diesel/src/query_builder/functions.rs

@@ -460,10 +460,10 @@ pub fn insert_or_ignore_into<T: Table>(target: T) -> IncompleteInsertOrIgnoreSta
 /// Creates a bare select statement, with no from clause. Primarily used for
 /// testing diesel itself, but likely useful for third party crates as well. The
 /// given expressions must be selectable from anywhere.
-pub fn select<T>(expression: T) -> crate::dsl::BareSelect<T>
+pub fn select<T>(expression: T) -> crate::dsl::select<T>
 where
     T: Expression,
-    crate::dsl::BareSelect<T>: AsQuery,
+    crate::dsl::select<T>: AsQuery,
 {
     SelectStatement::new(
         SelectClause(expression),

diesel_compile_tests/tests/fail/array_expressions_must_be_correct_type.stderr

@@ -26,11 +26,11 @@ error[E0277]: Cannot select `f64` from `NoFromClause`
 note: required by a bound in `diesel::select`
  --> $DIESEL/src/query_builder/functions.rs
   |
-  | pub fn select<T>(expression: T) -> crate::dsl::BareSelect<T>
+  | pub fn select<T>(expression: T) -> crate::dsl::select<T>
   |        ------ required by a bound in this function
 ...
-  |     crate::dsl::BareSelect<T>: AsQuery,
-  |                                ^^^^^^^ required by this bound in `select`
+  |     crate::dsl::select<T>: AsQuery,
+  |                            ^^^^^^^ required by this bound in `select`
   = note: consider using `--verbose` to print the full type name to the console
   = note: consider using `--verbose` to print the full type name to the console
 
@@ -60,11 +60,11 @@ error[E0277]: the trait bound `f64: ValidGrouping<()>` is not satisfied
 note: required by a bound in `diesel::select`
  --> $DIESEL/src/query_builder/functions.rs
   |
-  | pub fn select<T>(expression: T) -> crate::dsl::BareSelect<T>
+  | pub fn select<T>(expression: T) -> crate::dsl::select<T>
   |        ------ required by a bound in this function
 ...
-  |     crate::dsl::BareSelect<T>: AsQuery,
-  |                                ^^^^^^^ required by this bound in `select`
+  |     crate::dsl::select<T>: AsQuery,
+  |                            ^^^^^^^ required by this bound in `select`
   = note: consider using `--verbose` to print the full type name to the console
   = note: consider using `--verbose` to print the full type name to the console
 

diesel_compile_tests/tests/fail/array_expressions_must_be_same_type.stderr

@@ -26,11 +26,11 @@ error[E0277]: Cannot select `f64` from `NoFromClause`
 note: required by a bound in `diesel::select`
   --> $DIESEL/src/query_builder/functions.rs
    |
-   | pub fn select<T>(expression: T) -> crate::dsl::BareSelect<T>
+   | pub fn select<T>(expression: T) -> crate::dsl::select<T>
    |        ------ required by a bound in this function
 ...
-   |     crate::dsl::BareSelect<T>: AsQuery,
-   |                                ^^^^^^^ required by this bound in `select`
+   |     crate::dsl::select<T>: AsQuery,
+   |                            ^^^^^^^ required by this bound in `select`
    = note: consider using `--verbose` to print the full type name to the console
    = note: consider using `--verbose` to print the full type name to the console
    = note: consider using `--verbose` to print the full type name to the console
@@ -62,11 +62,11 @@ error[E0277]: the trait bound `f64: ValidGrouping<()>` is not satisfied
 note: required by a bound in `diesel::select`
   --> $DIESEL/src/query_builder/functions.rs
    |
-   | pub fn select<T>(expression: T) -> crate::dsl::BareSelect<T>
+   | pub fn select<T>(expression: T) -> crate::dsl::select<T>
    |        ------ required by a bound in this function
 ...
-   |     crate::dsl::BareSelect<T>: AsQuery,
-   |                                ^^^^^^^ required by this bound in `select`
+   |     crate::dsl::select<T>: AsQuery,
+   |                            ^^^^^^^ required by this bound in `select`
    = note: consider using `--verbose` to print the full type name to the console
    = note: consider using `--verbose` to print the full type name to the console
    = note: consider using `--verbose` to print the full type name to the console
@@ -269,11 +269,11 @@ error[E0277]: Cannot select `{integer}` from `NoFromClause`
 note: required by a bound in `diesel::select`
   --> $DIESEL/src/query_builder/functions.rs
    |
-   | pub fn select<T>(expression: T) -> crate::dsl::BareSelect<T>
+   | pub fn select<T>(expression: T) -> crate::dsl::select<T>
    |        ------ required by a bound in this function
 ...
-   |     crate::dsl::BareSelect<T>: AsQuery,
-   |                                ^^^^^^^ required by this bound in `select`
+   |     crate::dsl::select<T>: AsQuery,
+   |                            ^^^^^^^ required by this bound in `select`
    = note: consider using `--verbose` to print the full type name to the console
    = note: consider using `--verbose` to print the full type name to the console
    = note: consider using `--verbose` to print the full type name to the console
@@ -305,11 +305,11 @@ error[E0277]: the trait bound `{integer}: ValidGrouping<()>` is not satisfied
 note: required by a bound in `diesel::select`
   --> $DIESEL/src/query_builder/functions.rs
    |
-   | pub fn select<T>(expression: T) -> crate::dsl::BareSelect<T>
+   | pub fn select<T>(expression: T) -> crate::dsl::select<T>
    |        ------ required by a bound in this function
 ...
-   |     crate::dsl::BareSelect<T>: AsQuery,
-   |                                ^^^^^^^ required by this bound in `select`
+   |     crate::dsl::select<T>: AsQuery,
+   |                            ^^^^^^^ required by this bound in `select`
    = note: consider using `--verbose` to print the full type name to the console
    = note: consider using `--verbose` to print the full type name to the console
    = note: consider using `--verbose` to print the full type name to the console

diesel_derives/src/lib.rs

@@ -1778,12 +1778,11 @@ pub fn derive_multiconnection(input: TokenStream) -> TokenStream {
 /// ```
 /// # Limitations
 ///
-/// While this attribute tries to support as much of diesels built-in DSL as possible it's unfortunally not
-/// possible to support everything. Notable unsupported types are:
+/// While this attribute tries to support as much of diesels built-in DSL as possible it's
+/// unfortunately not possible to support everything. Notable unsupported types are:
 ///
 /// * Update statements
 /// * Insert from select statements
-/// * Select statements without from clause
 /// * Query constructed by `diesel::sql_query`
 /// * Expressions using `diesel::dsl::sql`
 ///

diesel_derives/tests/auto_type.rs

@@ -2,6 +2,7 @@
 use diesel::dsl::*;
 use diesel::helper_types::*;
 use diesel::prelude::*;
+use diesel::sql_types;
 
 table! {
     users {
@@ -172,10 +173,11 @@ fn test_insert1() -> _ {
     insert_into(users::table).values(users::id.eq(42_i32))
 }
 
-/*
-#[auto_type]
+/*#[auto_type]
 fn test_insert2() -> _ {
-    users::table.insert_into(users::table).into_columns(users::all_columns)
+    users::table
+        .insert_into(users::table)
+        .into_columns(users::all_columns)
 }*/
 
 #[auto_type]
@@ -188,11 +190,10 @@ fn test_insert_or_replace() -> _ {
     replace_into(users::table).values(users::id.eq(42_i32))
 }
 
-/*
 #[auto_type]
 fn test_bare_select() -> _ {
-    select(1_i32.into_sql::<Integer>())
-}*/
+    select(1_i32.into_sql::<sql_types::Integer>())
+}
 
 #[cfg(feature = "postgres")]
 #[auto_type]

diesel_tests/tests/types_roundtrip.rs

@@ -26,7 +26,7 @@ where
         + Clone
         + ::std::fmt::Debug
         + 'static,
-    for<'a> dsl::BareSelect<<T as AsExpression<ST>>::Expression>:
+    for<'a> dsl::select<<T as AsExpression<ST>>::Expression>:
         AsQuery + LoadQuery<'a, TestConnection, T>,
 {
     let connection = &mut connection_without_transaction();