Process validation attributes in newtype structs

schemars/tests/expected/validate_newtype.json

@@ -0,0 +1,8 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "title": "NewType",
+  "type": "integer",
+  "format": "uint8",
+  "maximum": 10.0,
+  "minimum": 0.0
+}

schemars/tests/validate.rs

@@ -46,3 +46,11 @@ pub struct Inner {
 fn validate() -> TestResult {
     test_default_generated_schema::<Struct>("validate")
 }
+
+#[derive(Debug, JsonSchema)]
+pub struct NewType(#[validate(range(max = 10))] u8);
+
+#[test]
+fn validate_newtype() -> TestResult {
+    test_default_generated_schema::<NewType>("validate_newtype")
+}

schemars_derive/src/schema_exprs.rs

@@ -61,7 +61,7 @@ fn expr_for_field(field: &Field, allow_ref: bool) -> TokenStream {
     let span = field.original.span();
     let gen = quote!(gen);
 
-    if allow_ref {
+    field.validation_attrs.apply_to_schema(if allow_ref {
         quote_spanned! {span=>
             {
                 #type_def
@@ -75,7 +75,7 @@ fn expr_for_field(field: &Field, allow_ref: bool) -> TokenStream {
                 <#ty as schemars::JsonSchema>::json_schema(#gen)
             }
         }
-    }
+    })
 }
 
 pub fn type_for_field_schema(field: &Field, local_id: usize) -> (syn::Type, Option<TokenStream>) {