Chore filter const generics (#1118)

This commit will filter out const generics from being added to the
schema composing because the value is not used in anyway.

Perhaps in some future release the real support of const generics could
be experimented.

Fixes #1115

Author: juhaku

utoipa-gen/CHANGELOG.md

@@ -26,6 +26,7 @@
 
 ### Fixed
 
+* Chore filter const generics (https://github.com/juhaku/utoipa/pull/1118)
 * Fix impl `ToSchema` for container types (https://github.com/juhaku/utoipa/pull/1107)
 * Fix description on `inline` field (https://github.com/juhaku/utoipa/pull/1102)
 * Fix `title` on unnamed struct and references (https://github.com/juhaku/utoipa/pull/1101)

utoipa-gen/src/component.rs

@@ -1184,7 +1184,10 @@ impl ComponentSchema {
                     let mut object_schema_reference = SchemaReference::default();
 
                     if let Some(children) = &type_tree.children {
-                        let children_name = Self::compose_name(children)?;
+                        let children_name = Self::compose_name(
+                            Self::filter_const_generics(children, container.generics),
+                            container.generics,
+                        )?;
                         name_tokens.extend(quote! { std::borrow::Cow::Owned(format!("{}_{}", < #rewritten_path as utoipa::ToSchema >::name(), #children_name)) });
                     } else {
                         name_tokens.extend(
@@ -1205,7 +1208,8 @@ impl ComponentSchema {
                             schema_references.extend(Self::compose_child_references(children)?);
 
                             let composed_generics =
-                                Self::compose_generics(children)?.collect::<Array<_>>();
+                                Self::compose_generics(children, container.generics)?
+                                    .collect::<Array<_>>();
                             quote_spanned! {type_path.span()=>
                                 <#rewritten_path as utoipa::__dev::ComposeSchema>::compose(#composed_generics.to_vec())
                             }
@@ -1242,8 +1246,11 @@ impl ComponentSchema {
                         // only set schema references tokens for concrete non generic types
                         if index.is_none() {
                             let reference_tokens = if let Some(children) = &type_tree.children {
-                                let composed_generics =
-                                    Self::compose_generics(children)?.collect::<Array<_>>();
+                                let composed_generics = Self::compose_generics(
+                                    Self::filter_const_generics(children, container.generics),
+                                    container.generics,
+                                )?
+                                .collect::<Array<_>>();
                                 quote! { <#rewritten_path as utoipa::__dev::ComposeSchema>::compose(#composed_generics.to_vec()) }
                             } else {
                                 quote! { <#rewritten_path as utoipa::PartialSchema>::schema() }
@@ -1356,7 +1363,10 @@ impl ComponentSchema {
         Ok(())
     }
 
-    fn compose_name<'tr, I>(children: I) -> Result<TokenStream, Diagnostics>
+    fn compose_name<'tr, I>(
+        children: I,
+        generics: &'tr Generics,
+    ) -> Result<TokenStream, Diagnostics>
     where
         I: IntoIterator<Item = &'tr TypeTree<'tr>>,
     {
@@ -1365,12 +1375,12 @@ impl ComponentSchema {
             .map(|type_tree| {
                 let name = type_tree
                     .path
-                    .as_ref()
+                    .as_deref()
                     .expect("Generic ValueType::Object must have path");
-                let rewritten_name = name.as_ref().rewrite_path()?;
+                let rewritten_name = name.rewrite_path()?;
 
                 if let Some(children) = &type_tree.children {
-                    let children_name = Self::compose_name(children)?;
+                    let children_name = Self::compose_name(Self::filter_const_generics(children, generics), generics)?;
 
                     Ok(quote! { std::borrow::Cow::Owned(format!("{}_{}", <#rewritten_name as utoipa::ToSchema>::name(), #children_name)) })
                 } else {
@@ -1384,6 +1394,7 @@ impl ComponentSchema {
 
     fn compose_generics<'v, I: IntoIterator<Item = &'v TypeTree<'v>>>(
         children: I,
+        generics: &'v Generics,
     ) -> Result<impl Iterator<Item = TokenStream> + 'v, Diagnostics>
     where
         <I as std::iter::IntoIterator>::IntoIter: 'v,
@@ -1395,7 +1406,7 @@ impl ComponentSchema {
                 .expect("inline TypeTree ValueType::Object must have child path if generic");
             let rewritten_path = path.rewrite_path()?;
             if let Some(children) = &child.children {
-                let items = Self::compose_generics(children)?.collect::<Array<_>>();
+                let items = Self::compose_generics(Self::filter_const_generics(children, generics), generics)?.collect::<Array<_>>();
                 Ok(quote! { <#rewritten_path as utoipa::__dev::ComposeSchema>::compose(#items.to_vec()) })
             } else {
                 Ok(quote! { <#rewritten_path as utoipa::PartialSchema>::schema() })
@@ -1406,6 +1417,31 @@ impl ComponentSchema {
         Ok(iter)
     }
 
+    fn filter_const_generics<'v, I: IntoIterator<Item = &'v TypeTree<'v>>>(
+        children: I,
+        generics: &'v Generics,
+    ) -> impl IntoIterator<Item = &'v TypeTree<'v>> + 'v
+    where
+        <I as std::iter::IntoIterator>::IntoIter: 'v,
+    {
+        children.into_iter().filter(|type_tree| {
+            let path = type_tree
+                .path
+                .as_deref()
+                .expect("child TypeTree must have a Path, did you call this on array or tuple?");
+            let is_const = path
+                .get_ident()
+                .map(|path_ident| {
+                    generics.params.iter().any(
+                        |param| matches!(param, GenericParam::Const(ty) if ty.ident == *path_ident),
+                    )
+                })
+                .unwrap_or(false);
+
+            !is_const
+        })
+    }
+
     fn compose_child_references<'a, I: IntoIterator<Item = &'a TypeTree<'a>> + 'a>(
         children: I,
     ) -> Result<impl Iterator<Item = SchemaReference> + 'a, Diagnostics> {
@@ -1416,8 +1452,8 @@ impl ComponentSchema {
             } else if type_tree.value_type == ValueType::Object {
                 let type_path = type_tree
                     .path
-                    .as_ref()
-                    .expect("Object TypePath must have type path, compose child references").as_ref();
+                    .as_deref()
+                    .expect("Object TypePath must have type path, compose child references");
 
                 let rewritten_path = type_path.rewrite_path()?;
 

utoipa-gen/tests/schema_derive_test.rs

@@ -5854,3 +5854,35 @@ fn schema_manual_impl() {
         })
     )
 }
+
+#[test]
+fn const_generic_test() {
+    #![allow(unused)]
+
+    #[derive(ToSchema)]
+    pub struct ArrayResponse<T: ToSchema, const N: usize> {
+        array: [T; N],
+    }
+
+    #[derive(ToSchema)]
+    struct CombinedResponse<T: ToSchema, const N: usize> {
+        pub array_response: ArrayResponse<T, N>,
+    }
+
+    use utoipa::PartialSchema;
+    let schema = <CombinedResponse<String, 1> as PartialSchema>::schema();
+    let value = serde_json::to_value(schema).expect("schema is JSON serializable");
+
+    assert_json_eq! {
+        value,
+        json!({
+            "properties": {
+                "array_response": {
+                    "$ref": "#/components/schemas/ArrayResponse_String"
+                }
+            },
+            "required": ["array_response"],
+            "type": "object"
+        })
+    }
+}