feat: better errors in derive(ValueDeserialize) (#1095)

obmarg · Nov 12, 2024 · 735321a · 735321a
1 parent 1695b40
commit 735321a
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Showing 2 changed files with 30 additions and 25 deletions.
diff --git a/cynic-parser-deser-macros/src/attributes.rs b/cynic-parser-deser-macros/src/attributes.rs
@@ -9,7 +9,7 @@ pub struct StructAttribute {
 }
 
 impl StructAttribute {
-    pub fn from_attrs(attrs: &[Attribute]) -> Self {
+    pub fn from_attrs(attrs: &[Attribute]) -> Result<Self, syn::Error> {
         attrs
             .iter()
             .filter(|attr| attr.path().is_ident("deser"))
@@ -34,11 +34,10 @@ impl StructAttribute {
                     } else {
                         Err(meta.error("unsupported attribute"))
                     }
-                })
-                .unwrap();
-                output
+                })?;
+                Ok::<_, syn::Error>(output)
             })
-            .fold(Self::default(), |acc, inc| acc.merge(inc))
+            .try_fold(Self::default(), |acc, inc| Ok(acc.merge(inc?)))
     }
 
     fn merge(mut self, other: Self) -> Self {
@@ -69,7 +68,7 @@ pub enum FieldDefault {
 }
 
 impl FieldAttributes {
-    pub fn from_field(field: &Field, defaults: FieldAttributes) -> Self {
+    pub fn from_field(field: &Field, defaults: FieldAttributes) -> Result<Self, syn::Error> {
         field
             .attrs
             .iter()
@@ -101,11 +100,10 @@ impl FieldAttributes {
                     } else {
                         Err(meta.error("unsupported attribute"))
                     }
-                })
-                .unwrap();
-                output
+                })?;
+                Ok::<_, syn::Error>(output)
             })
-            .fold(defaults, |acc, inc| acc.merge(inc))
+            .try_fold(defaults, |acc, inc| Ok(acc.merge(inc?)))
     }
 
     fn merge(mut self, other: Self) -> Self {

diff --git a/cynic-parser-deser-macros/src/lib.rs b/cynic-parser-deser-macros/src/lib.rs
@@ -2,7 +2,7 @@ mod attributes;
 mod renames;
 
 use attributes::{FieldAttributes, FieldDefault, StructAttribute};
-use proc_macro2::TokenStream;
+use proc_macro2::{Span, TokenStream};
 use quote::{format_ident, quote, ToTokens};
 use syn::{parse_quote, Fields};
 
@@ -12,21 +12,25 @@ pub fn value_deserialize(input: proc_macro::TokenStream) -> proc_macro::TokenStr
 
     let ast = syn::parse_macro_input!(input as syn::DeriveInput);
 
-    match value_deser_impl(ast) {
+    match value_deser_impl(&ast) {
         Ok(tokens) => tokens.into(),
-        Err(_) => {
-            todo!("put out a dummy impl as well as the compile errors");
-            // e.to_compile_error().into(),
+        Err(error) => {
+            // TODO: Output a dummy impl...
+            let compile_error = error.to_compile_error();
+            quote! {
+                #compile_error
+            }
+            .into()
         }
     }
 }
 
-fn value_deser_impl(ast: syn::DeriveInput) -> Result<TokenStream, ()> {
-    let syn::Data::Struct(data) = ast.data else {
+fn value_deser_impl(ast: &syn::DeriveInput) -> Result<TokenStream, syn::Error> {
+    let syn::Data::Struct(data) = &ast.data else {
         panic!("ValueDeserialize can only be derived on structs");
     };
 
-    let ident = ast.ident;
+    let ident = &ast.ident;
 
     let (original_impl_generics, ty_generics, where_clause) = ast.generics.split_for_impl();
     let (impl_generics, deser_lifetime) = match ast.generics.lifetimes().next() {
@@ -45,23 +49,26 @@ fn value_deser_impl(ast: syn::DeriveInput) -> Result<TokenStream, ()> {
         }
     };
 
-    let Fields::Named(named) = data.fields else {
-        panic!("ValueDeserialize can only be derived on structs with named fields");
+    let Fields::Named(named) = &data.fields else {
+        return Err(syn::Error::new(
+            Span::call_site(),
+            "ValueDeserialize can only be derived on structs with named fields",
+        ));
     };
 
-    let struct_attrs = StructAttribute::from_attrs(&ast.attrs);
+    let struct_attrs = StructAttribute::from_attrs(&ast.attrs)?;
     let default_field_attrs = struct_attrs.to_field_defaults();
 
     let fields = named
         .named
         .iter()
         .map(|field| {
-            (
+            Ok::<_, syn::Error>((
                 field,
-                FieldAttributes::from_field(field, default_field_attrs.clone()),
-            )
+                FieldAttributes::from_field(field, default_field_attrs.clone())?,
+            ))
         })
-        .collect::<Vec<_>>();
+        .collect::<Result<Vec<_>, _>>()?;
 
     let field_names = named
         .named