chore!: simplify discriminants handling in schema derives (#241)

There’s no need for a separate discriminant variable and assignment statement in the derived code. The value of the discriminant can be included directly in the entry for the variant. Co-authored-by: dj8yf0μl <26653921+dj8yfo@users.noreply.github.com>
near · Oct 25, 2023 · 71a9d4d · 71a9d4d
1 parent f1f820b
commit 71a9d4d
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Showing 16 changed files with 80 additions and 142 deletions.
diff --git a/borsh-derive/src/internals/schema/enums/mod.rs b/borsh-derive/src/internals/schema/enums/mod.rs
@@ -39,7 +39,6 @@ pub fn process(input: &ItemEnum, cratename: Path) -> syn::Result<TokenStream2> {
     let discriminants = Discriminants::new(&input.variants);
 
     // Generate functions that return the schema for variants.
-    let mut discriminant_variables = vec![];
     let mut variants_defs = vec![];
     let mut inner_defs = TokenStream2::new();
     let mut add_recursive_defs = TokenStream2::new();
@@ -60,14 +59,12 @@ pub fn process(input: &ItemEnum, cratename: Path) -> syn::Result<TokenStream2> {
         inner_defs.extend(variant_output.inner_struct);
         add_recursive_defs.extend(variant_output.add_definitions_recursively_call);
         variants_defs.push(variant_output.variant_entry);
-        discriminant_variables.push(variant_output.discriminant_variable_assignment);
     }
 
     let type_definitions = quote! {
         fn add_definitions_recursively(definitions: &mut #cratename::__private::maybestd::collections::BTreeMap<#cratename::schema::Declaration, #cratename::schema::Definition>) {
             #inner_defs
             #add_recursive_defs
-            #(#discriminant_variables)*
             let definition = #cratename::schema::Definition::Enum {
                 tag_width: 1,
                 variants: #cratename::__private::maybestd::vec![#(#variants_defs),*],
@@ -93,8 +90,6 @@ struct VariantOutput {
     inner_struct: TokenStream2,
     /// call to `add_definitions_recursively`.
     add_definitions_recursively_call: TokenStream2,
-    /// declaration of `u8` variable, holding the value for discriminant of a variant
-    discriminant_variable_assignment: TokenStream2,
     /// entry with a variant's declaration, element in vector of whole enum's definition
     variant_entry: TokenStream2,
 }
@@ -108,18 +103,9 @@ struct DiscriminantInfo<'a> {
 fn process_discriminant(
     variant_ident: &Ident,
     info: DiscriminantInfo<'_>,
-) -> syn::Result<(Ident, TokenStream2)> {
-    let discriminant_value =
-        info.discriminants
-            .get(variant_ident, info.use_discriminant, info.variant_idx)?;
-
-    let discriminant_variable_name = format!("discriminant_{}", info.variant_idx);
-    let discriminant_variable = Ident::new(&discriminant_variable_name, Span::call_site());
-
-    let discriminant_variable_assignment = quote! {
-        let #discriminant_variable: u8 = #discriminant_value;
-    };
-    Ok((discriminant_variable, discriminant_variable_assignment))
+) -> syn::Result<TokenStream2> {
+    info.discriminants
+        .get(variant_ident, info.use_discriminant, info.variant_idx)
 }
 
 fn process_variant(
@@ -139,21 +125,21 @@ fn process_variant(
         inner_struct_definition(variant, cratename, &full_variant_ident, enum_generics);
     let (_ig, inner_struct_ty_generics, _wc) = inner_struct_generics.split_for_impl();
 
-    let add_definitions_recursively_call = quote! {
-        <#full_variant_ident #inner_struct_ty_generics as #cratename::BorshSchema>::add_definitions_recursively(definitions);
+    let variant_type = quote! {
+        <#full_variant_ident #inner_struct_ty_generics as #cratename::BorshSchema>
     };
+    let discriminant_value = process_discriminant(&variant.ident, discriminant_info)?;
 
-    let (discriminant_variable, discriminant_variable_assignment) =
-        process_discriminant(&variant.ident, discriminant_info)?;
-
-    let variant_entry = quote! {
-        (#discriminant_variable as i64, #variant_name.to_string(), <#full_variant_ident #inner_struct_ty_generics as #cratename::BorshSchema>::declaration())
-    };
     Ok(VariantOutput {
         inner_struct,
-        add_definitions_recursively_call,
-        variant_entry,
-        discriminant_variable_assignment,
+        add_definitions_recursively_call: quote! {
+            #variant_type::add_definitions_recursively(definitions);
+        },
+        variant_entry: quote! {
+            (u8::from(#discriminant_value) as i64,
+             #variant_name.into(),
+             #variant_type::declaration())
+        },
     })
 }
 

diff --git a/borsh-derive/src/internals/schema/enums/snapshots/borsh_discriminant_false.snap b/borsh-derive/src/internals/schema/enums/snapshots/borsh_discriminant_false.snap
@@ -42,23 +42,17 @@ impl borsh::BorshSchema for X {
         <XD as borsh::BorshSchema>::add_definitions_recursively(definitions);
         <XE as borsh::BorshSchema>::add_definitions_recursively(definitions);
         <XF as borsh::BorshSchema>::add_definitions_recursively(definitions);
-        let discriminant_0: u8 = 0u8;
-        let discriminant_1: u8 = 1u8;
-        let discriminant_2: u8 = 2u8;
-        let discriminant_3: u8 = 3u8;
-        let discriminant_4: u8 = 4u8;
-        let discriminant_5: u8 = 5u8;
         let definition = borsh::schema::Definition::Enum {
             tag_width: 1,
             variants: borsh::__private::maybestd::vec![
-                (discriminant_0 as i64, "A".to_string(), < XA as borsh::BorshSchema >
-                ::declaration()), (discriminant_1 as i64, "B".to_string(), < XB as
-                borsh::BorshSchema > ::declaration()), (discriminant_2 as i64, "C"
-                .to_string(), < XC as borsh::BorshSchema > ::declaration()),
-                (discriminant_3 as i64, "D".to_string(), < XD as borsh::BorshSchema >
-                ::declaration()), (discriminant_4 as i64, "E".to_string(), < XE as
-                borsh::BorshSchema > ::declaration()), (discriminant_5 as i64, "F"
-                .to_string(), < XF as borsh::BorshSchema > ::declaration())
+                (u8::from(0u8) as i64, "A".into(), < XA as borsh::BorshSchema >
+                ::declaration()), (u8::from(1u8) as i64, "B".into(), < XB as
+                borsh::BorshSchema > ::declaration()), (u8::from(2u8) as i64, "C".into(),
+                < XC as borsh::BorshSchema > ::declaration()), (u8::from(3u8) as i64, "D"
+                .into(), < XD as borsh::BorshSchema > ::declaration()), (u8::from(4u8) as
+                i64, "E".into(), < XE as borsh::BorshSchema > ::declaration()),
+                (u8::from(5u8) as i64, "F".into(), < XF as borsh::BorshSchema >
+                ::declaration())
             ],
         };
         borsh::schema::add_definition(

diff --git a/borsh-derive/src/internals/schema/enums/snapshots/borsh_discriminant_true.snap b/borsh-derive/src/internals/schema/enums/snapshots/borsh_discriminant_true.snap
@@ -42,23 +42,17 @@ impl borsh::BorshSchema for X {
         <XD as borsh::BorshSchema>::add_definitions_recursively(definitions);
         <XE as borsh::BorshSchema>::add_definitions_recursively(definitions);
         <XF as borsh::BorshSchema>::add_definitions_recursively(definitions);
-        let discriminant_0: u8 = 0;
-        let discriminant_1: u8 = 20;
-        let discriminant_2: u8 = 20 + 1;
-        let discriminant_3: u8 = 20 + 1 + 1;
-        let discriminant_4: u8 = 10;
-        let discriminant_5: u8 = 10 + 1;
         let definition = borsh::schema::Definition::Enum {
             tag_width: 1,
             variants: borsh::__private::maybestd::vec![
-                (discriminant_0 as i64, "A".to_string(), < XA as borsh::BorshSchema >
-                ::declaration()), (discriminant_1 as i64, "B".to_string(), < XB as
-                borsh::BorshSchema > ::declaration()), (discriminant_2 as i64, "C"
-                .to_string(), < XC as borsh::BorshSchema > ::declaration()),
-                (discriminant_3 as i64, "D".to_string(), < XD as borsh::BorshSchema >
-                ::declaration()), (discriminant_4 as i64, "E".to_string(), < XE as
-                borsh::BorshSchema > ::declaration()), (discriminant_5 as i64, "F"
-                .to_string(), < XF as borsh::BorshSchema > ::declaration())
+                (u8::from(0) as i64, "A".into(), < XA as borsh::BorshSchema >
+                ::declaration()), (u8::from(20) as i64, "B".into(), < XB as
+                borsh::BorshSchema > ::declaration()), (u8::from(20 + 1) as i64, "C"
+                .into(), < XC as borsh::BorshSchema > ::declaration()), (u8::from(20 + 1
+                + 1) as i64, "D".into(), < XD as borsh::BorshSchema > ::declaration()),
+                (u8::from(10) as i64, "E".into(), < XE as borsh::BorshSchema >
+                ::declaration()), (u8::from(10 + 1) as i64, "F".into(), < XF as
+                borsh::BorshSchema > ::declaration())
             ],
         };
         borsh::schema::add_definition(

diff --git a/borsh-derive/src/internals/schema/enums/snapshots/complex_enum.snap b/borsh-derive/src/internals/schema/enums/snapshots/complex_enum.snap
@@ -35,19 +35,15 @@ impl borsh::BorshSchema for A {
         <AEggs as borsh::BorshSchema>::add_definitions_recursively(definitions);
         <ASalad as borsh::BorshSchema>::add_definitions_recursively(definitions);
         <ASausage as borsh::BorshSchema>::add_definitions_recursively(definitions);
-        let discriminant_0: u8 = 0u8;
-        let discriminant_1: u8 = 1u8;
-        let discriminant_2: u8 = 2u8;
-        let discriminant_3: u8 = 3u8;
         let definition = borsh::schema::Definition::Enum {
             tag_width: 1,
             variants: borsh::__private::maybestd::vec![
-                (discriminant_0 as i64, "Bacon".to_string(), < ABacon as
-                borsh::BorshSchema > ::declaration()), (discriminant_1 as i64, "Eggs"
-                .to_string(), < AEggs as borsh::BorshSchema > ::declaration()),
-                (discriminant_2 as i64, "Salad".to_string(), < ASalad as
-                borsh::BorshSchema > ::declaration()), (discriminant_3 as i64, "Sausage"
-                .to_string(), < ASausage as borsh::BorshSchema > ::declaration())
+                (u8::from(0u8) as i64, "Bacon".into(), < ABacon as borsh::BorshSchema >
+                ::declaration()), (u8::from(1u8) as i64, "Eggs".into(), < AEggs as
+                borsh::BorshSchema > ::declaration()), (u8::from(2u8) as i64, "Salad"
+                .into(), < ASalad as borsh::BorshSchema > ::declaration()),
+                (u8::from(3u8) as i64, "Sausage".into(), < ASausage as borsh::BorshSchema
+                > ::declaration())
             ],
         };
         borsh::schema::add_definition(

diff --git a/borsh-derive/src/internals/schema/enums/snapshots/complex_enum_generics.snap b/borsh-derive/src/internals/schema/enums/snapshots/complex_enum_generics.snap
@@ -43,19 +43,15 @@ where
         <AEggs as borsh::BorshSchema>::add_definitions_recursively(definitions);
         <ASalad<C> as borsh::BorshSchema>::add_definitions_recursively(definitions);
         <ASausage<W> as borsh::BorshSchema>::add_definitions_recursively(definitions);
-        let discriminant_0: u8 = 0u8;
-        let discriminant_1: u8 = 1u8;
-        let discriminant_2: u8 = 2u8;
-        let discriminant_3: u8 = 3u8;
         let definition = borsh::schema::Definition::Enum {
             tag_width: 1,
             variants: borsh::__private::maybestd::vec![
-                (discriminant_0 as i64, "Bacon".to_string(), < ABacon as
-                borsh::BorshSchema > ::declaration()), (discriminant_1 as i64, "Eggs"
-                .to_string(), < AEggs as borsh::BorshSchema > ::declaration()),
-                (discriminant_2 as i64, "Salad".to_string(), < ASalad < C > as
-                borsh::BorshSchema > ::declaration()), (discriminant_3 as i64, "Sausage"
-                .to_string(), < ASausage < W > as borsh::BorshSchema > ::declaration())
+                (u8::from(0u8) as i64, "Bacon".into(), < ABacon as borsh::BorshSchema >
+                ::declaration()), (u8::from(1u8) as i64, "Eggs".into(), < AEggs as
+                borsh::BorshSchema > ::declaration()), (u8::from(2u8) as i64, "Salad"
+                .into(), < ASalad < C > as borsh::BorshSchema > ::declaration()),
+                (u8::from(3u8) as i64, "Sausage".into(), < ASausage < W > as
+                borsh::BorshSchema > ::declaration())
             ],
         };
         borsh::schema::add_definition(

diff --git a/...ve/src/internals/schema/enums/snapshots/complex_enum_generics_borsh_skip_named_field.snap b/...ve/src/internals/schema/enums/snapshots/complex_enum_generics_borsh_skip_named_field.snap
@@ -45,20 +45,15 @@ where
         <AEggs as borsh::BorshSchema>::add_definitions_recursively(definitions);
         <ASalad<C> as borsh::BorshSchema>::add_definitions_recursively(definitions);
         <ASausage<W, U> as borsh::BorshSchema>::add_definitions_recursively(definitions);
-        let discriminant_0: u8 = 0u8;
-        let discriminant_1: u8 = 1u8;
-        let discriminant_2: u8 = 2u8;
-        let discriminant_3: u8 = 3u8;
         let definition = borsh::schema::Definition::Enum {
             tag_width: 1,
             variants: borsh::__private::maybestd::vec![
-                (discriminant_0 as i64, "Bacon".to_string(), < ABacon as
-                borsh::BorshSchema > ::declaration()), (discriminant_1 as i64, "Eggs"
-                .to_string(), < AEggs as borsh::BorshSchema > ::declaration()),
-                (discriminant_2 as i64, "Salad".to_string(), < ASalad < C > as
-                borsh::BorshSchema > ::declaration()), (discriminant_3 as i64, "Sausage"
-                .to_string(), < ASausage < W, U > as borsh::BorshSchema >
-                ::declaration())
+                (u8::from(0u8) as i64, "Bacon".into(), < ABacon as borsh::BorshSchema >
+                ::declaration()), (u8::from(1u8) as i64, "Eggs".into(), < AEggs as
+                borsh::BorshSchema > ::declaration()), (u8::from(2u8) as i64, "Salad"
+                .into(), < ASalad < C > as borsh::BorshSchema > ::declaration()),
+                (u8::from(3u8) as i64, "Sausage".into(), < ASausage < W, U > as
+                borsh::BorshSchema > ::declaration())
             ],
         };
         borsh::schema::add_definition(

diff --git a/...ve/src/internals/schema/enums/snapshots/complex_enum_generics_borsh_skip_tuple_field.snap b/...ve/src/internals/schema/enums/snapshots/complex_enum_generics_borsh_skip_tuple_field.snap
@@ -45,19 +45,15 @@ where
         <AEggs as borsh::BorshSchema>::add_definitions_recursively(definitions);
         <ASalad<C> as borsh::BorshSchema>::add_definitions_recursively(definitions);
         <ASausage<W> as borsh::BorshSchema>::add_definitions_recursively(definitions);
-        let discriminant_0: u8 = 0u8;
-        let discriminant_1: u8 = 1u8;
-        let discriminant_2: u8 = 2u8;
-        let discriminant_3: u8 = 3u8;
         let definition = borsh::schema::Definition::Enum {
             tag_width: 1,
             variants: borsh::__private::maybestd::vec![
-                (discriminant_0 as i64, "Bacon".to_string(), < ABacon as
-                borsh::BorshSchema > ::declaration()), (discriminant_1 as i64, "Eggs"
-                .to_string(), < AEggs as borsh::BorshSchema > ::declaration()),
-                (discriminant_2 as i64, "Salad".to_string(), < ASalad < C > as
-                borsh::BorshSchema > ::declaration()), (discriminant_3 as i64, "Sausage"
-                .to_string(), < ASausage < W > as borsh::BorshSchema > ::declaration())
+                (u8::from(0u8) as i64, "Bacon".into(), < ABacon as borsh::BorshSchema >
+                ::declaration()), (u8::from(1u8) as i64, "Eggs".into(), < AEggs as
+                borsh::BorshSchema > ::declaration()), (u8::from(2u8) as i64, "Salad"
+                .into(), < ASalad < C > as borsh::BorshSchema > ::declaration()),
+                (u8::from(3u8) as i64, "Sausage".into(), < ASausage < W > as
+                borsh::BorshSchema > ::declaration())
             ],
         };
         borsh::schema::add_definition(

diff --git a/borsh-derive/src/internals/schema/enums/snapshots/filter_foreign_attrs.snap b/borsh-derive/src/internals/schema/enums/snapshots/filter_foreign_attrs.snap
@@ -29,14 +29,12 @@ impl borsh::BorshSchema for A {
         }
         <AB as borsh::BorshSchema>::add_definitions_recursively(definitions);
         <ANegative as borsh::BorshSchema>::add_definitions_recursively(definitions);
-        let discriminant_0: u8 = 0u8;
-        let discriminant_1: u8 = 1u8;
         let definition = borsh::schema::Definition::Enum {
             tag_width: 1,
             variants: borsh::__private::maybestd::vec![
-                (discriminant_0 as i64, "B".to_string(), < AB as borsh::BorshSchema >
-                ::declaration()), (discriminant_1 as i64, "Negative".to_string(), <
-                ANegative as borsh::BorshSchema > ::declaration())
+                (u8::from(0u8) as i64, "B".into(), < AB as borsh::BorshSchema >
+                ::declaration()), (u8::from(1u8) as i64, "Negative".into(), < ANegative
+                as borsh::BorshSchema > ::declaration())
             ],
         };
         borsh::schema::add_definition(

diff --git a/borsh-derive/src/internals/schema/enums/snapshots/generic_associated_type.snap b/borsh-derive/src/internals/schema/enums/snapshots/generic_associated_type.snap
@@ -56,15 +56,12 @@ where
         <EnumParametrizedC<
             T,
         > as borsh::BorshSchema>::add_definitions_recursively(definitions);
-        let discriminant_0: u8 = 0u8;
-        let discriminant_1: u8 = 1u8;
         let definition = borsh::schema::Definition::Enum {
             tag_width: 1,
             variants: borsh::__private::maybestd::vec![
-                (discriminant_0 as i64, "B".to_string(), < EnumParametrizedB < K, V > as
-                borsh::BorshSchema > ::declaration()), (discriminant_1 as i64, "C"
-                .to_string(), < EnumParametrizedC < T > as borsh::BorshSchema >
-                ::declaration())
+                (u8::from(0u8) as i64, "B".into(), < EnumParametrizedB < K, V > as
+                borsh::BorshSchema > ::declaration()), (u8::from(1u8) as i64, "C".into(),
+                < EnumParametrizedC < T > as borsh::BorshSchema > ::declaration())
             ],
         };
         borsh::schema::add_definition(

diff --git a/...h-derive/src/internals/schema/enums/snapshots/generic_associated_type_param_override.snap b/...h-derive/src/internals/schema/enums/snapshots/generic_associated_type_param_override.snap
@@ -57,15 +57,12 @@ where
         <EnumParametrizedC<
             T,
         > as borsh::BorshSchema>::add_definitions_recursively(definitions);
-        let discriminant_0: u8 = 0u8;
-        let discriminant_1: u8 = 1u8;
         let definition = borsh::schema::Definition::Enum {
             tag_width: 1,
             variants: borsh::__private::maybestd::vec![
-                (discriminant_0 as i64, "B".to_string(), < EnumParametrizedB < K, V > as
-                borsh::BorshSchema > ::declaration()), (discriminant_1 as i64, "C"
-                .to_string(), < EnumParametrizedC < T > as borsh::BorshSchema >
-                ::declaration())
+                (u8::from(0u8) as i64, "B".into(), < EnumParametrizedB < K, V > as
+                borsh::BorshSchema > ::declaration()), (u8::from(1u8) as i64, "C".into(),
+                < EnumParametrizedC < T > as borsh::BorshSchema > ::declaration())
             ],
         };
         borsh::schema::add_definition(

diff --git a/borsh-derive/src/internals/schema/enums/snapshots/recursive_enum.snap b/borsh-derive/src/internals/schema/enums/snapshots/recursive_enum.snap
@@ -37,14 +37,12 @@ where
         struct AC<K: Key>(K, Vec<A>);
         <AB<K, V> as borsh::BorshSchema>::add_definitions_recursively(definitions);
         <AC<K> as borsh::BorshSchema>::add_definitions_recursively(definitions);
-        let discriminant_0: u8 = 0u8;
-        let discriminant_1: u8 = 1u8;
         let definition = borsh::schema::Definition::Enum {
             tag_width: 1,
             variants: borsh::__private::maybestd::vec![
-                (discriminant_0 as i64, "B".to_string(), < AB < K, V > as
-                borsh::BorshSchema > ::declaration()), (discriminant_1 as i64, "C"
-                .to_string(), < AC < K > as borsh::BorshSchema > ::declaration())
+                (u8::from(0u8) as i64, "B".into(), < AB < K, V > as borsh::BorshSchema >
+                ::declaration()), (u8::from(1u8) as i64, "C".into(), < AC < K > as
+                borsh::BorshSchema > ::declaration())
             ],
         };
         borsh::schema::add_definition(

diff --git a/borsh-derive/src/internals/schema/enums/snapshots/simple_enum.snap b/borsh-derive/src/internals/schema/enums/snapshots/simple_enum.snap
@@ -22,14 +22,12 @@ impl borsh::BorshSchema for A {
         struct AEggs;
         <ABacon as borsh::BorshSchema>::add_definitions_recursively(definitions);
         <AEggs as borsh::BorshSchema>::add_definitions_recursively(definitions);
-        let discriminant_0: u8 = 0u8;
-        let discriminant_1: u8 = 1u8;
         let definition = borsh::schema::Definition::Enum {
             tag_width: 1,
             variants: borsh::__private::maybestd::vec![
-                (discriminant_0 as i64, "Bacon".to_string(), < ABacon as
-                borsh::BorshSchema > ::declaration()), (discriminant_1 as i64, "Eggs"
-                .to_string(), < AEggs as borsh::BorshSchema > ::declaration())
+                (u8::from(0u8) as i64, "Bacon".into(), < ABacon as borsh::BorshSchema >
+                ::declaration()), (u8::from(1u8) as i64, "Eggs".into(), < AEggs as
+                borsh::BorshSchema > ::declaration())
             ],
         };
         borsh::schema::add_definition(