Adding support for doc comments on EnumDiscriminants generated type (#140)

Author: linclelinkpart5

strum_macros/src/helpers/metadata.rs

@@ -19,6 +19,7 @@ pub mod kw {
     custom_keyword!(derive);
     custom_keyword!(name);
     custom_keyword!(vis);
+    custom_keyword!(doc);
 
     // variant metadata
     custom_keyword!(message);
@@ -58,6 +59,7 @@ pub enum EnumDiscriminantsMeta {
     Derive { kw: kw::derive, paths: Vec<Path> },
     Name { kw: kw::name, name: Ident },
     Vis { kw: kw::vis, vis: Visibility },
+    Doc { kw: kw::doc, doc: LitStr },
     Other { path: Path, nested: TokenStream },
 }
 
@@ -84,6 +86,12 @@ impl Parse for EnumDiscriminantsMeta {
             parenthesized!(content in input);
             let vis = content.parse()?;
             Ok(EnumDiscriminantsMeta::Vis { kw, vis })
+        } else if input.peek(kw::doc) {
+            let kw = input.parse()?;
+            let content;
+            parenthesized!(content in input);
+            let doc = content.parse()?;
+            Ok(EnumDiscriminantsMeta::Doc { kw, doc })
         } else {
             let path = input.parse()?;
             let content;
@@ -100,6 +108,7 @@ impl Spanned for EnumDiscriminantsMeta {
             EnumDiscriminantsMeta::Derive { kw, .. } => kw.span,
             EnumDiscriminantsMeta::Name { kw, .. } => kw.span,
             EnumDiscriminantsMeta::Vis { kw, .. } => kw.span,
+            EnumDiscriminantsMeta::Doc { kw, .. } => kw.span,
             EnumDiscriminantsMeta::Other { path, .. } => path.span(),
         }
     }

strum_macros/src/helpers/type_props.rs

@@ -1,7 +1,7 @@
 use proc_macro2::TokenStream;
 use quote::quote;
 use std::default::Default;
-use syn::{DeriveInput, Ident, Path, Visibility};
+use syn::{DeriveInput, Ident, LitStr, Path, Visibility};
 
 use super::case_style::CaseStyle;
 use super::metadata::{DeriveInputExt, EnumDiscriminantsMeta, EnumMeta};
@@ -18,6 +18,7 @@ pub struct StrumTypeProperties {
     pub discriminant_name: Option<Ident>,
     pub discriminant_others: Vec<TokenStream>,
     pub discriminant_vis: Option<Visibility>,
+    pub discriminant_docs: Vec<LitStr>,
 }
 
 impl HasTypeProperties for DeriveInput {
@@ -64,6 +65,9 @@ impl HasTypeProperties for DeriveInput {
                     vis_kw = Some(kw);
                     output.discriminant_vis = Some(vis);
                 }
+                EnumDiscriminantsMeta::Doc { doc, .. } => {
+                    output.discriminant_docs.push(doc);
+                }
                 EnumDiscriminantsMeta::Other { path, nested } => {
                     output.discriminant_others.push(quote! { #path(#nested) });
                 }

strum_macros/src/macros/enum_discriminants.rs

@@ -29,6 +29,15 @@ pub fn enum_discriminants_inner(ast: &DeriveInput) -> syn::Result<TokenStream> {
         #[derive(Clone, Copy, Debug, PartialEq, Eq, #(#derives),*)]
     };
 
+    // Create #[doc] attrs for new generated type.
+    let docs = type_properties.discriminant_docs;
+
+    let docs = quote! {
+        #(#[doc = #docs])*
+    };
+
+    println!("{:?}", docs);
+
     // Work out the name
     let default_name = syn::Ident::new(
         &format!("{}Discriminants", name.to_string()),
@@ -125,7 +134,7 @@ pub fn enum_discriminants_inner(ast: &DeriveInput) -> syn::Result<TokenStream> {
     };
 
     Ok(quote! {
-        /// Auto-generated discriminant enum variants
+        #docs
         #derives
         #(#[ #pass_though_attributes ])*
         #discriminants_vis enum #discriminants_name {