support variadic queries in the trait definition

src/lib.rs

@@ -190,7 +190,7 @@ macro_rules! query_group {
         tokens[{
             $(
                 $(#[$method_attr:meta])*
-                fn $method_name:ident($key_name:ident: $key_ty:ty) -> $value_ty:ty {
+                fn $method_name:ident($($key_name:ident: $key_ty:ty),* $(,)*) -> $value_ty:ty {
                     type $QueryType:ident;
                     $(storage $storage:ident;)* // FIXME(rust-lang/rust#48075) should be `?`
                     $(use fn $fn_path:path;)* // FIXME(rust-lang/rust#48075) should be `?`
@@ -201,9 +201,9 @@ macro_rules! query_group {
         $($trait_attr)* $v trait $query_trait: $($crate::plumbing::GetQueryTable<$QueryType> +)* $($header)* {
             $(
                 $(#[$method_attr])*
-                fn $method_name(&self, key: $key_ty) -> $value_ty {
+                fn $method_name(&self, $($key_name: $key_ty),*) -> $value_ty {
                     <Self as $crate::plumbing::GetQueryTable<$QueryType>>::get_query_table(self)
-                        .get(key)
+                        .get(($($key_name),*))
                 }
             )*
         }
@@ -216,7 +216,7 @@ macro_rules! query_group {
             where
                 DB: $query_trait,
             {
-                type Key = $key_ty;
+                type Key = ($($key_ty),*);
                 type Value = $value_ty;
                 type Storage = $crate::query_group! { @storage_ty[DB, Self, $($storage)*] };
             }

tests/variadic.rs

@@ -0,0 +1,67 @@
+salsa::query_group! {
+    trait HelloWorldDatabase: salsa::Database {
+        fn none() -> u32 {
+            type None;
+        }
+
+        fn one(k: u32) -> u32 {
+            type One;
+        }
+
+        fn two(a: u32, b: u32) -> u32 {
+            type Two;
+        }
+
+        fn trailing(a: u32, b: u32,) -> u32 {
+            type Trailing;
+        }
+    }
+}
+
+fn none(_db: &impl HelloWorldDatabase, (): ()) -> u32 {
+    22
+}
+
+fn one(_db: &impl HelloWorldDatabase, k: u32) -> u32 {
+    k * 2
+}
+
+fn two(_db: &impl HelloWorldDatabase, (a, b): (u32, u32)) -> u32 {
+    a * b
+}
+
+fn trailing(_db: &impl HelloWorldDatabase, (a, b): (u32, u32)) -> u32 {
+    a - b
+}
+
+#[derive(Default)]
+struct DatabaseStruct {
+    runtime: salsa::Runtime<DatabaseStruct>,
+}
+
+impl salsa::Database for DatabaseStruct {
+    fn salsa_runtime(&self) -> &salsa::Runtime<DatabaseStruct> {
+        &self.runtime
+    }
+}
+
+salsa::database_storage! {
+    struct DatabaseStorage for DatabaseStruct {
+        impl HelloWorldDatabase {
+            fn none() for None;
+            fn one() for One;
+            fn two() for Two;
+            fn trailing() for Trailing;
+        }
+    }
+}
+
+#[test]
+fn execute() {
+    let db = DatabaseStruct::default();
+
+    assert_eq!(db.none(), 22);
+    assert_eq!(db.one(11), 22);
+    assert_eq!(db.two(11, 2), 22);
+    assert_eq!(db.trailing(24, 2), 22);
+}