feature: add id paramater to interned structs

components/salsa-macro-rules/src/setup_interned_struct_sans_lifetime.rs

@@ -14,6 +14,9 @@ macro_rules! setup_interned_struct_sans_lifetime {
         // Name of the `'db` lifetime that the user gave
         db_lt: $db_lt:lifetime,
 
+        // the salsa ID
+        id: $Id:path,
+
         // Name user gave for `new`
         new_fn: $new_fn:ident,
 
@@ -55,7 +58,7 @@ macro_rules! setup_interned_struct_sans_lifetime {
         $(#[$attr])*
         #[derive(Copy, Clone, PartialEq, PartialOrd, Eq, Ord, Hash)]
         $vis struct $Struct(
-            salsa::Id,
+            $Id,
             std::marker::PhantomData < &'static  salsa::plumbing::interned::Value < $Struct > >
         );
 
@@ -96,10 +99,12 @@ macro_rules! setup_interned_struct_sans_lifetime {
                 type Data<'a> = StructData<'a>;
                 type Struct<'a> = $Struct;
                 fn struct_from_id<'db>(id: salsa::Id) -> Self::Struct<'db> {
-                    $Struct(id, std::marker::PhantomData)
+                    use $zalsa::FromId;
+                    $Struct(<$Id>::from_id(id), std::marker::PhantomData)
                 }
                 fn deref_struct(s: Self::Struct<'_>) -> salsa::Id {
-                    s.0
+                    use $zalsa::AsId;
+                    s.0.as_id()
                 }
             }
 
@@ -118,13 +123,13 @@ macro_rules! setup_interned_struct_sans_lifetime {
 
             impl $zalsa::AsId for $Struct {
                 fn as_id(&self) -> salsa::Id {
-                    self.0
+                    self.0.as_id()
                 }
             }
 
             impl $zalsa::FromId for $Struct {
                 fn from_id(id: salsa::Id) -> Self {
-                    Self(id, std::marker::PhantomData)
+                    Self(<$Id>::from_id(id), std::marker::PhantomData)
                 }
             }
 

components/salsa-macros/src/accumulator.rs

@@ -42,6 +42,7 @@ impl AllowedOptions for Accumulator {
     const RECOVERY_FN: bool = false;
     const LRU: bool = false;
     const CONSTRUCTOR_NAME: bool = false;
+    const ID: bool = true;
 }
 
 struct StructMacro {

components/salsa-macros/src/input.rs

@@ -55,6 +55,8 @@ impl crate::options::AllowedOptions for InputStruct {
     const LRU: bool = false;
 
     const CONSTRUCTOR_NAME: bool = true;
+
+    const ID: bool = true;
 }
 
 impl SalsaStructAllowedOptions for InputStruct {

components/salsa-macros/src/interned.rs

@@ -56,6 +56,8 @@ impl crate::options::AllowedOptions for InternedStruct {
     const LRU: bool = false;
 
     const CONSTRUCTOR_NAME: bool = true;
+
+    const ID: bool = true;
 }
 
 impl SalsaStructAllowedOptions for InternedStruct {

components/salsa-macros/src/interned_sans_lifetime.rs

@@ -32,6 +32,7 @@ pub(crate) fn interned_sans_lifetime(
 
 type InternedArgs = Options<InternedStruct>;
 
+#[derive(Debug)]
 struct InternedStruct;
 
 impl crate::options::AllowedOptions for InternedStruct {
@@ -56,6 +57,8 @@ impl crate::options::AllowedOptions for InternedStruct {
     const LRU: bool = false;
 
     const CONSTRUCTOR_NAME: bool = true;
+
+    const ID: bool = true;
 }
 
 impl SalsaStructAllowedOptions for InternedStruct {
@@ -93,6 +96,7 @@ impl Macro {
         let field_tys = salsa_struct.field_tys();
         let field_indexed_tys = salsa_struct.field_indexed_tys();
         let generate_debug_impl = salsa_struct.generate_debug_impl();
+        let id = salsa_struct.id();
 
         let zalsa = self.hygiene.ident("zalsa");
         let zalsa_struct = self.hygiene.ident("zalsa_struct");
@@ -108,6 +112,7 @@ impl Macro {
                     vis: #vis,
                     Struct: #struct_ident,
                     db_lt: #db_lt,
+                    id: #id,
                     new_fn: #new_fn,
                     field_options: [#(#field_options),*],
                     field_ids: [#(#field_ids),*],

components/salsa-macros/src/options.rs

@@ -7,6 +7,7 @@ use syn::{ext::IdentExt, spanned::Spanned};
 /// are required and trailing commas are permitted. The options accepted
 /// for any particular location are configured via the `AllowedOptions`
 /// trait.
+#[derive(Debug)]
 pub(crate) struct Options<A: AllowedOptions> {
     /// The `return_ref` option is used to signal that field/return type is "by ref"
     ///
@@ -66,6 +67,12 @@ pub(crate) struct Options<A: AllowedOptions> {
     /// If this is `Some`, the value is the `<ident>`.
     pub constructor_name: Option<syn::Ident>,
 
+    /// The `id = <path>` option is used to set a custom ID for interrned structs.
+    ///
+    /// The custom ID needs to handle
+    /// If this is `Some`, the value is the `<ident>`.
+    pub id: Option<syn::Path>,
+
     /// Remember the `A` parameter, which plays no role after parsing.
     phantom: PhantomData<A>,
 }
@@ -85,6 +92,7 @@ impl<A: AllowedOptions> Default for Options<A> {
             phantom: Default::default(),
             lru: Default::default(),
             singleton: Default::default(),
+            id: Default::default(),
         }
     }
 }
@@ -102,6 +110,7 @@ pub(crate) trait AllowedOptions {
     const RECOVERY_FN: bool;
     const LRU: bool;
     const CONSTRUCTOR_NAME: bool;
+    const ID: bool;
 }
 
 type Equals = syn::Token![=];
@@ -252,7 +261,7 @@ impl<A: AllowedOptions> syn::parse::Parse for Options<A> {
                 }
             } else if ident == "constructor" {
                 if A::CONSTRUCTOR_NAME {
-                    let _eq = Equals::parse(input)?;
+                    let _eq: syn::token::Eq = Equals::parse(input)?;
                     let ident = syn::Ident::parse(input)?;
                     if let Some(old) = std::mem::replace(&mut options.constructor_name, Some(ident))
                     {
@@ -267,6 +276,17 @@ impl<A: AllowedOptions> syn::parse::Parse for Options<A> {
                         "`constructor` option not allowed here",
                     ));
                 }
+            } else if ident == "id" {
+                if A::ID {
+                    let _eq = Equals::parse(input)?;
+                    let path = syn::Path::parse(input)?;
+                    options.id = Some(path);
+                } else {
+                    return Err(syn::Error::new(
+                        ident.span(),
+                        "`id` option not allowed here",
+                    ));
+                }
             } else {
                 return Err(syn::Error::new(
                     ident.span(),

components/salsa-macros/src/salsa_struct.rs

@@ -118,6 +118,13 @@ where
         }
     }
 
+    pub(crate) fn id(&self) -> syn::Path {
+        match &self.args.id {
+            Some(id) => id.clone(),
+            None => parse_quote!(salsa::Id),
+        }
+    }
+
     /// Disallow `#[id]` attributes on the fields of this struct.
     ///
     /// If an `#[id]` field is found, return an error.

components/salsa-macros/src/tracked_fn.rs

@@ -44,6 +44,8 @@ impl crate::options::AllowedOptions for TrackedFn {
     const LRU: bool = true;
 
     const CONSTRUCTOR_NAME: bool = false;
+
+    const ID: bool = true;
 }
 
 struct Macro {

components/salsa-macros/src/tracked_struct.rs

@@ -50,6 +50,8 @@ impl crate::options::AllowedOptions for TrackedStruct {
     const LRU: bool = false;
 
     const CONSTRUCTOR_NAME: bool = true;
+
+    const ID: bool = true;
 }
 
 impl SalsaStructAllowedOptions for TrackedStruct {

tests/interned-sans-lifetime.rs

@@ -2,23 +2,38 @@ use expect_test::expect;
 use std::path::{Path, PathBuf};
 use test_log::test;
 
-#[salsa::interned_sans_lifetime]
+#[derive(Clone, Copy, Hash, Debug, PartialEq, Eq, PartialOrd, Ord)]
+struct CustomSalsaIdWrapper(salsa::Id);
+
+impl salsa::plumbing::AsId for CustomSalsaIdWrapper {
+    fn as_id(&self) -> salsa::Id {
+        self.0
+    }
+}
+
+impl salsa::plumbing::FromId for CustomSalsaIdWrapper {
+    fn from_id(id: salsa::Id) -> Self {
+        CustomSalsaIdWrapper(id)
+    }
+}
+
+#[salsa::interned_sans_lifetime(id = CustomSalsaIdWrapper)]
 struct InternedString {
     data: String,
 }
 
-#[salsa::interned_sans_lifetime]
+#[salsa::interned_sans_lifetime(id = CustomSalsaIdWrapper)]
 struct InternedPair {
     data: (InternedString, InternedString),
 }
 
-#[salsa::interned_sans_lifetime]
+#[salsa::interned_sans_lifetime(id = CustomSalsaIdWrapper)]
 struct InternedTwoFields {
     data1: String,
     data2: String,
 }
 
-#[salsa::interned_sans_lifetime]
+#[salsa::interned_sans_lifetime(id = CustomSalsaIdWrapper)]
 struct InternedVec {
     data1: Vec<String>,
 }