Allow destructuring in command parameters (#217)

macros/src/command/mod.rs

@@ -79,7 +79,6 @@ struct ParamArgs {
 
 /// Part of the Invocation struct. Represents a single parameter of a Discord command.
 struct CommandParameter {
-    ident: syn::Ident,
     name: String,
     type_: syn::Type,
     args: ParamArgs,
@@ -162,18 +161,14 @@ pub fn command(
     // Collect argument names/types/attributes to insert into generated function
     let mut parameters = Vec::new();
     for command_param in function.sig.inputs.iter_mut().skip(1) {
+        let span = command_param.span();
+
         let pattern = match command_param {
-            syn::FnArg::Typed(x) => &mut *x,
+            syn::FnArg::Typed(x) => x,
             syn::FnArg::Receiver(r) => {
                 return Err(syn::Error::new(r.span(), "self argument is invalid here").into());
             }
         };
-        let ident = match &*pattern.pat {
-            syn::Pat::Ident(pat_ident) => &pat_ident.ident,
-            x => {
-                return Err(syn::Error::new(x.span(), "must use an identifier pattern here").into())
-            }
-        };
 
         let attrs = pattern
             .attrs
@@ -182,15 +177,19 @@ pub fn command(
             .collect::<Result<Vec<_>, _>>()?;
         let attrs = <ParamArgs as darling::FromMeta>::from_list(&attrs)?;
 
+        let name = if let Some(rename) = &attrs.rename {
+            rename.clone()
+        } else if let syn::Pat::Ident(ident) = &*pattern.pat {
+            ident.ident.to_string().trim_start_matches("r#").into()
+        } else {
+            let message = "#[rename = \"...\"] must be specified for pattern parameters";
+            return Err(syn::Error::new(pattern.pat.span(), message).into());
+        };
         parameters.push(CommandParameter {
-            ident: ident.clone(),
-            name: attrs
-                .rename
-                .clone()
-                .unwrap_or_else(|| ident.to_string().trim_start_matches("r#").to_string()),
+            name,
             type_: (*pattern.ty).clone(),
             args: attrs,
-            span: command_param.span(),
+            span,
         });
     }
 

macros/src/command/prefix.rs

@@ -1,4 +1,5 @@
 use super::Invocation;
+use quote::format_ident;
 use syn::spanned::Spanned as _;
 
 fn quote_parameter(p: &super::CommandParameter) -> Result<proc_macro2::TokenStream, syn::Error> {
@@ -14,23 +15,20 @@ fn quote_parameter(p: &super::CommandParameter) -> Result<proc_macro2::TokenStre
         (false, true, false) => Modifier::Rest,
         (false, false, true) => Modifier::Flag,
         _ => {
-            return Err(syn::Error::new(
-                p.span,
-                "modifiers like #[lazy] or #[rest] currently cannot be used together",
-            )
-            .into())
+            let message = "modifiers like #[lazy] or #[rest] currently cannot be used together";
+            return Err(syn::Error::new(p.span, message));
         }
     };
     let type_ = &p.type_;
     Ok(match modifier {
         Modifier::Flag => {
             if p.type_ != syn::parse_quote! { bool } {
-                return Err(syn::Error::new(p.type_.span(), "Must use bool for flags").into());
+                return Err(syn::Error::new(p.type_.span(), "Must use bool for flags"));
             }
             // TODO: doesn't work for r#keywords :( I cant be arsed to fix this rn because basically
             // nobody uses this feature anyways and I'd have to go change the macro_rules macro to
             // not accept non-quoted idents anymore
-            let literal = proc_macro2::Literal::string(&p.ident.to_string());
+            let literal = proc_macro2::Literal::string(&p.name);
             quote::quote! { #[flag] (#literal) }
         }
         Modifier::Lazy => quote::quote! { #[lazy] (#type_) },
@@ -40,7 +38,9 @@ fn quote_parameter(p: &super::CommandParameter) -> Result<proc_macro2::TokenStre
 }
 
 pub fn generate_prefix_action(inv: &Invocation) -> Result<proc_macro2::TokenStream, syn::Error> {
-    let param_idents = inv.parameters.iter().map(|p| &p.ident).collect::<Vec<_>>();
+    let param_idents = (0..inv.parameters.len())
+        .map(|i| format_ident!("poise_param_{i}"))
+        .collect::<Vec<_>>();
     let param_specs = inv
         .parameters
         .iter()
@@ -52,7 +52,6 @@ pub fn generate_prefix_action(inv: &Invocation) -> Result<proc_macro2::TokenStre
     };
 
     Ok(quote::quote! {
-        #[allow(clippy::used_underscore_binding)]
         |ctx| Box::pin(async move {
             let ( #( #param_idents, )* .. ) = ::poise::parse_prefix_args!(
                 ctx.serenity_context, ctx.msg, ctx.args, 0 =>

macros/src/command/slash.rs

@@ -1,5 +1,6 @@
 use super::Invocation;
 use crate::util::extract_type_parameter;
+use quote::format_ident;
 use syn::spanned::Spanned as _;
 
 pub fn generate_parameters(inv: &Invocation) -> Result<Vec<proc_macro2::TokenStream>, syn::Error> {
@@ -143,7 +144,9 @@ pub fn generate_slash_action(inv: &Invocation) -> Result<proc_macro2::TokenStrea
         }
     }
 
-    let param_identifiers = inv.parameters.iter().map(|p| &p.ident).collect::<Vec<_>>();
+    let param_identifiers = (0..inv.parameters.len())
+        .map(|i| format_ident!("poise_param_{i}"))
+        .collect::<Vec<_>>();
     let param_names = inv.parameters.iter().map(|p| &p.name).collect::<Vec<_>>();
 
     let param_types = inv