Upgrade to darling 0.20 and syn v2 (#222)

macros/Cargo.toml

@@ -11,7 +11,7 @@ repository = "https://github.com/serenity-rs/poise/"
 proc-macro = true
 
 [dependencies]
-syn = { version = "1.0.64", features = ["full", "fold"] }
+syn = { version = "2", features = ["fold"] }
 quote = "1.0.9"
 proc-macro2 = "1.0.24"
-darling = "0.14.1"
+darling = "0.20"

macros/src/choice_parameter.rs

@@ -41,11 +41,11 @@ pub fn choice_parameter(input: syn::DeriveInput) -> Result<TokenStream, darling:
             .into());
         }
 
-        let attrs = variant
+        let attrs: Vec<_> = variant
             .attrs
             .into_iter()
-            .map(|attr| attr.parse_meta().map(syn::NestedMeta::Meta))
-            .collect::<Result<Vec<_>, _>>()?;
+            .map(|attr| darling::ast::NestedMeta::Meta(attr.meta))
+            .collect();
         let mut attrs = <VariantAttribute as darling::FromMeta>::from_list(&attrs)?;
 
         let main_name = if attrs.name.is_empty() {

macros/src/command/mod.rs

@@ -100,11 +100,13 @@ pub struct Invocation {
 fn extract_help_from_doc_comments(attrs: &[syn::Attribute]) -> (Option<String>, Option<String>) {
     let mut doc_lines = String::new();
     for attr in attrs {
-        if attr.path == quote::format_ident!("doc").into() {
-            for token in attr.tokens.clone() {
-                if let Ok(literal) = syn::parse2::<syn::LitStr>(token.into()) {
-                    doc_lines += literal.value().trim(); // Trim lines like rustdoc does
-                    doc_lines += "\n";
+        if let syn::Meta::NameValue(doc_attr) = &attr.meta {
+            if doc_attr.path == quote::format_ident!("doc").into() {
+                if let syn::Expr::Lit(lit_expr) = &doc_attr.value {
+                    if let syn::Lit::Str(literal) = &lit_expr.lit {
+                        doc_lines += literal.value().trim(); // Trim lines like rustdoc does
+                        doc_lines += "\n";
+                    }
                 }
             }
         }
@@ -170,11 +172,11 @@ pub fn command(
             }
         };
 
-        let attrs = pattern
+        let attrs: Vec<_> = pattern
             .attrs
             .drain(..)
-            .map(|attr| attr.parse_meta().map(syn::NestedMeta::Meta))
-            .collect::<Result<Vec<_>, _>>()?;
+            .map(|attr| darling::ast::NestedMeta::Meta(attr.meta))
+            .collect();
         let attrs = <ParamArgs as darling::FromMeta>::from_list(&attrs)?;
 
         let name = if let Some(rename) = &attrs.rename {
@@ -332,7 +334,7 @@ fn generate_command(mut inv: Invocation) -> Result<proc_macro2::TokenStream, dar
     let function = &inv.function;
     Ok(quote::quote! {
         #[allow(clippy::str_to_string)]
-        #function_visibility fn #function_ident#function_generics() -> ::poise::Command<
+        #function_visibility fn #function_ident #function_generics() -> ::poise::Command<
             <#ctx_type_with_static as poise::_GetGenerics>::U,
             <#ctx_type_with_static as poise::_GetGenerics>::E,
         > {

macros/src/lib.rs

@@ -185,7 +185,11 @@ exact desugaring
 */
 #[proc_macro_attribute]
 pub fn command(args: TokenStream, function: TokenStream) -> TokenStream {
-    let args = syn::parse_macro_input!(args as Vec<syn::NestedMeta>);
+    let args = match darling::ast::NestedMeta::parse_meta_list(args.into()) {
+        Ok(x) => x,
+        Err(e) => return e.into_compile_error().into(),
+    };
+
     let args = match <command::CommandArgs as darling::FromMeta>::from_list(&args) {
         Ok(x) => x,
         Err(e) => return e.write_errors().into(),

macros/src/modal.rs

@@ -35,22 +35,22 @@ pub fn modal(input: syn::DeriveInput) -> Result<TokenStream, darling::Error> {
         }
     };
 
-    let struct_attrs = input
+    let struct_attrs: Vec<_> = input
         .attrs
-        .iter()
-        .map(|attr| attr.parse_meta().map(syn::NestedMeta::Meta))
-        .collect::<Result<Vec<_>, _>>()?;
+        .into_iter()
+        .map(|attr| darling::ast::NestedMeta::Meta(attr.meta))
+        .collect();
     let struct_attrs = <StructAttributes as darling::FromMeta>::from_list(&struct_attrs)?;
 
     let mut builders = Vec::new();
     let mut parsers = Vec::new();
     for field in fields {
         // Extract data from syn::Field
-        let field_attrs = field
+        let field_attrs: Vec<_> = field
             .attrs
-            .iter()
-            .map(|attr| attr.parse_meta().map(syn::NestedMeta::Meta))
-            .collect::<Result<Vec<_>, _>>()?;
+            .into_iter()
+            .map(|attr| darling::ast::NestedMeta::Meta(attr.meta))
+            .collect();
         let field_attrs = <FieldAttributes as darling::FromMeta>::from_list(&field_attrs)?;
         let field_ident = field.ident.unwrap();
 

macros/src/util.rs

@@ -39,7 +39,7 @@ impl syn::fold::Fold for AllLifetimesToStatic {
 #[derive(Debug)]
 pub struct List<T>(pub Vec<T>);
 impl<T: darling::FromMeta> darling::FromMeta for List<T> {
-    fn from_list(items: &[::syn::NestedMeta]) -> darling::Result<Self> {
+    fn from_list(items: &[::darling::ast::NestedMeta]) -> darling::Result<Self> {
         items
             .iter()
             .map(|item| T::from_nested_meta(item))
@@ -57,7 +57,7 @@ impl<T> Default for List<T> {
 #[derive(Debug)]
 pub struct Tuple2<T>(pub T, pub T);
 impl<T: darling::FromMeta> darling::FromMeta for Tuple2<T> {
-    fn from_list(items: &[::syn::NestedMeta]) -> darling::Result<Self> {
+    fn from_list(items: &[::darling::ast::NestedMeta]) -> darling::Result<Self> {
         Ok(match items {
             [a, b] => Self(T::from_nested_meta(a)?, T::from_nested_meta(b)?),
             _ => {