Improved support for string enums (#4147)

CHANGELOG.md

@@ -23,6 +23,9 @@
 * Added `Debug` implementation to `JsError`.
   [#4136](https://github.com/rustwasm/wasm-bindgen/pull/4136)
 
+* Added support for `js_name` and `skip_typescript` attributes for string enums.
+  [#4147](https://github.com/rustwasm/wasm-bindgen/pull/4147)
+
 ### Changed
 
 * Implicitly enable reference type and multivalue transformations if the module already makes use of the corresponding target features.
@@ -79,6 +82,9 @@
 * Specify `"type": "module"` when deploying to nodejs-module
   [#4092](https://github.com/rustwasm/wasm-bindgen/pull/4092)
 
+* Fixed string enums not generating TypeScript types.
+  [#4147](https://github.com/rustwasm/wasm-bindgen/pull/4147)
+
 --------------------------------------------------------------------------------
 
 ## [0.2.93](https://github.com/rustwasm/wasm-bindgen/compare/0.2.92...0.2.93)

crates/backend/src/ast.rs

@@ -337,12 +337,18 @@ pub struct StringEnum {
     pub vis: syn::Visibility,
     /// The Rust enum's identifiers
     pub name: Ident,
+    /// The name of this string enum in JS/TS code
+    pub js_name: String,
     /// The Rust identifiers for the variants
     pub variants: Vec<Ident>,
     /// The JS string values of the variants
     pub variant_values: Vec<String>,
+    /// The doc comments on this enum, if any
+    pub comments: Vec<String>,
     /// Attributes to apply to the Rust enum
     pub rust_attrs: Vec<syn::Attribute>,
+    /// Whether to generate a typescript definition for this enum
+    pub generate_typescript: bool,
     /// Path to wasm_bindgen
     pub wasm_bindgen: Path,
 }

crates/backend/src/codegen.rs

@@ -1144,7 +1144,7 @@ impl ToTokens for ast::StringEnum {
     fn to_tokens(&self, tokens: &mut TokenStream) {
         let vis = &self.vis;
         let enum_name = &self.name;
-        let name_str = enum_name.to_string();
+        let name_str = self.js_name.to_string();
         let name_len = name_str.len() as u32;
         let name_chars = name_str.chars().map(u32::from);
         let variants = &self.variants;
@@ -1172,15 +1172,6 @@ impl ToTokens for ast::StringEnum {
 
         let wasm_bindgen = &self.wasm_bindgen;
 
-        let describe_variants = self.variant_values.iter().map(|variant_value| {
-            let length = variant_value.len() as u32;
-            let chars = variant_value.chars().map(u32::from);
-            quote! {
-                inform(#length);
-                #(inform(#chars);)*
-            }
-        });
-
         (quote! {
             #(#attrs)*
             #[non_exhaustive]
@@ -1257,7 +1248,6 @@ impl ToTokens for ast::StringEnum {
                     inform(#name_len);
                     #(inform(#name_chars);)*
                     inform(#variant_count);
-                    #(#describe_variants)*
                 }
             }
 

crates/backend/src/encode.rs

@@ -359,8 +359,14 @@ fn shared_import_type<'a>(i: &'a ast::ImportType, intern: &'a Interner) -> Impor
     }
 }
 
-fn shared_import_enum<'a>(_i: &'a ast::StringEnum, _intern: &'a Interner) -> StringEnum {
-    StringEnum {}
+fn shared_import_enum<'a>(i: &'a ast::StringEnum, _intern: &'a Interner) -> StringEnum<'a> {
+    StringEnum {
+        name: &i.js_name,
+        public: matches!(i.vis, syn::Visibility::Public(_)),
+        generate_typescript: i.generate_typescript,
+        variant_values: i.variant_values.iter().map(|x| &**x).collect(),
+        comments: i.comments.iter().map(|s| &**s).collect(),
+    }
 }
 
 fn shared_struct<'a>(s: &'a ast::Struct, intern: &'a Interner) -> Struct<'a> {

crates/cli-support/src/descriptor.rs

@@ -76,7 +76,6 @@ pub enum Descriptor {
         name: String,
         invalid: u32,
         hole: u32,
-        variant_values: Vec<String>,
     },
     RustStruct(String),
     Char,
@@ -171,12 +170,10 @@ impl Descriptor {
                 let variant_count = get(data);
                 let invalid = variant_count;
                 let hole = variant_count + 1;
-                let variant_values = (0..variant_count).map(|_| get_string(data)).collect();
                 Descriptor::StringEnum {
                     name,
                     invalid,
                     hole,
-                    variant_values,
                 }
             }
             RUST_STRUCT => {

crates/cli-support/src/js/binding.rs

@@ -576,20 +576,11 @@ fn instruction(
     log_error: &mut bool,
     constructor: &Option<String>,
 ) -> Result<(), Error> {
-    fn wasm_to_string_enum(variant_values: &[String], index: &str) -> String {
+    fn wasm_to_string_enum(name: &str, index: &str) -> String {
         // e.g. ["a","b","c"][someIndex]
-        let mut enum_val_expr = String::new();
-        enum_val_expr.push('[');
-        for variant in variant_values {
-            enum_val_expr.push_str(&format!("\"{variant}\","));
-        }
-        enum_val_expr.push(']');
-        enum_val_expr.push('[');
-        enum_val_expr.push_str(index);
-        enum_val_expr.push(']');
-        enum_val_expr
+        format!("__wbindgen_enum_{name}[{index}]")
     }
-    fn string_enum_to_wasm(variant_values: &[String], invalid: u32, enum_val: &str) -> String {
+    fn string_enum_to_wasm(name: &str, invalid: u32, enum_val: &str) -> String {
         // e.g. (["a","b","c"].indexOf(someEnumVal) + 1 || 4) - 1
         //                                                 |
         //                                           invalid + 1
@@ -598,16 +589,10 @@ fn instruction(
         // and with +1 we get 0 which is falsey, so we can use || to
         // substitute invalid+1. Finally, we just do -1 to get the correct
         // values for everything.
-        let mut enum_val_expr = String::new();
-        enum_val_expr.push_str("([");
-        for variant in variant_values.iter() {
-            enum_val_expr.push_str(&format!("\"{variant}\","));
-        }
-        enum_val_expr.push_str(&format!(
-            "].indexOf({enum_val}) + 1 || {invalid}) - 1",
+        format!(
+            "(__wbindgen_enum_{name}.indexOf({enum_val}) + 1 || {invalid}) - 1",
             invalid = invalid + 1
-        ));
-        enum_val_expr
+        )
     }
 
     match instr {
@@ -702,34 +687,31 @@ fn instruction(
             }
         }
 
-        Instruction::WasmToStringEnum { variant_values } => {
+        Instruction::WasmToStringEnum { name } => {
             let index = js.pop();
-            js.push(wasm_to_string_enum(variant_values, &index))
+            js.push(wasm_to_string_enum(name, &index))
         }
 
-        Instruction::OptionWasmToStringEnum { variant_values, .. } => {
+        Instruction::OptionWasmToStringEnum { name, .. } => {
             // Since hole is currently variant_count+1 and the lookup is
             // ["a","b","c"][index], the lookup will implicitly return map
             // the hole to undefined, because OOB indexes will return undefined.
             let index = js.pop();
-            js.push(wasm_to_string_enum(variant_values, &index))
+            js.push(wasm_to_string_enum(name, &index))
         }
 
-        Instruction::StringEnumToWasm {
-            variant_values,
-            invalid,
-        } => {
+        Instruction::StringEnumToWasm { name, invalid } => {
             let enum_val = js.pop();
-            js.push(string_enum_to_wasm(variant_values, *invalid, &enum_val))
+            js.push(string_enum_to_wasm(name, *invalid, &enum_val))
         }
 
         Instruction::OptionStringEnumToWasm {
-            variant_values,
+            name,
             invalid,
             hole,
         } => {
             let enum_val = js.pop();
-            let enum_val_expr = string_enum_to_wasm(variant_values, *invalid, &enum_val);
+            let enum_val_expr = string_enum_to_wasm(name, *invalid, &enum_val);
 
             // e.g. someEnumVal == undefined ? 4 : (string_enum_to_wasm(someEnumVal))
             //                  |

crates/cli-support/src/js/mod.rs

@@ -2,7 +2,7 @@ use crate::descriptor::VectorKind;
 use crate::intrinsic::Intrinsic;
 use crate::wit::{
     Adapter, AdapterId, AdapterJsImportKind, AdapterType, AuxExportedMethodKind, AuxReceiverKind,
-    AuxValue,
+    AuxStringEnum, AuxValue,
 };
 use crate::wit::{AdapterKind, Instruction, InstructionData};
 use crate::wit::{AuxEnum, AuxExport, AuxExportKind, AuxImport, AuxStruct};
@@ -2529,9 +2529,12 @@ __wbg_set_wasm(wasm);"
         pairs.sort_by_key(|(k, _)| *k);
         check_duplicated_getter_and_setter_names(&pairs)?;
 
-        for (_, e) in self.aux.enums.iter() {
+        for (_, e) in crate::sorted_iter(&self.aux.enums) {
             self.generate_enum(e)?;
         }
+        for (_, e) in crate::sorted_iter(&self.aux.string_enums) {
+            self.generate_string_enum(e)?;
+        }
 
         for s in self.aux.structs.iter() {
             self.generate_struct(s)?;
@@ -3808,6 +3811,42 @@ __wbg_set_wasm(wasm);"
         Ok(())
     }
 
+    fn generate_string_enum(&mut self, string_enum: &AuxStringEnum) -> Result<(), Error> {
+        let docs = format_doc_comments(&string_enum.comments, None);
+
+        let variants: Vec<_> = string_enum
+            .variant_values
+            .iter()
+            .map(|v| format!("\"{v}\""))
+            .collect();
+
+        if string_enum.generate_typescript {
+            self.typescript.push_str(&docs);
+            if string_enum.public {
+                self.typescript.push_str("export ");
+            }
+            self.typescript.push_str("type ");
+            self.typescript.push_str(&string_enum.name);
+            self.typescript.push_str(" = ");
+
+            if variants.is_empty() {
+                self.typescript.push_str("never");
+            } else {
+                self.typescript.push_str(&variants.join(" | "));
+            }
+
+            self.typescript.push_str(";\n");
+        }
+
+        self.global(&format!(
+            "const __wbindgen_enum_{name} = [{values}];\n",
+            name = string_enum.name,
+            values = variants.join(", ")
+        ));
+
+        Ok(())
+    }
+
     fn generate_struct(&mut self, struct_: &AuxStruct) -> Result<(), Error> {
         let class = require_class(&mut self.exported_classes, &struct_.name);
         class.comments = format_doc_comments(&struct_.comments, None);

crates/cli-support/src/wit/incoming.rs

@@ -108,11 +108,11 @@ impl InstructionBuilder<'_, '_> {
                     &[AdapterType::I32],
                 );
             },
-            Descriptor::StringEnum { name, variant_values, invalid, .. } => {
+            Descriptor::StringEnum { name, invalid, .. } => {
                 self.instruction(
                     &[AdapterType::StringEnum(name.clone())],
                     Instruction::StringEnumToWasm {
-                        variant_values: variant_values.clone(),
+                        name: name.clone(),
                         invalid: *invalid,
                     },
                     &[AdapterType::I32],
@@ -308,14 +308,13 @@ impl InstructionBuilder<'_, '_> {
             }
             Descriptor::StringEnum {
                 name,
-                variant_values,
                 invalid,
                 hole,
             } => {
                 self.instruction(
                     &[AdapterType::StringEnum(name.clone()).option()],
                     Instruction::OptionStringEnumToWasm {
-                        variant_values: variant_values.clone(),
+                        name: name.clone(),
                         invalid: *invalid,
                         hole: *hole,
                     },

crates/cli-support/src/wit/mod.rs

@@ -573,7 +573,7 @@ impl<'a> Context<'a> {
             decode::ImportKind::Static(s) => self.import_static(&import, s),
             decode::ImportKind::String(s) => self.import_string(s),
             decode::ImportKind::Type(t) => self.import_type(&import, t),
-            decode::ImportKind::Enum(_) => Ok(()),
+            decode::ImportKind::Enum(e) => self.string_enum(e),
         }
     }
 
@@ -865,6 +865,33 @@ impl<'a> Context<'a> {
         Ok(())
     }
 
+    fn string_enum(&mut self, string_enum: &decode::StringEnum<'_>) -> Result<(), Error> {
+        let aux = AuxStringEnum {
+            name: string_enum.name.to_string(),
+            public: string_enum.public,
+            comments: concatenate_comments(&string_enum.comments),
+            variant_values: string_enum
+                .variant_values
+                .iter()
+                .map(|v| v.to_string())
+                .collect(),
+            generate_typescript: string_enum.generate_typescript,
+        };
+        let mut result = Ok(());
+        self.aux
+            .string_enums
+            .entry(aux.name.clone())
+            .and_modify(|existing| {
+                result = Err(anyhow!(
+                    "duplicate string enums:\n{:?}\n{:?}",
+                    existing,
+                    aux
+                ));
+            })
+            .or_insert(aux);
+        result
+    }
+
     fn enum_(&mut self, enum_: decode::Enum<'_>) -> Result<(), Error> {
         let aux = AuxEnum {
             name: enum_.name.to_string(),

crates/cli-support/src/wit/nonstandard.rs

@@ -42,6 +42,9 @@ pub struct WasmBindgenAux {
     /// Auxiliary information to go into JS/TypeScript bindings describing the
     /// exported enums from Rust.
     pub enums: HashMap<String, AuxEnum>,
+    /// Auxiliary information to go into JS/TypeScript bindings describing the
+    /// exported string enums from Rust.
+    pub string_enums: HashMap<String, AuxStringEnum>,
 
     /// Auxiliary information to go into JS/TypeScript bindings describing the
     /// exported structs from Rust and their fields they've got exported.
@@ -172,6 +175,20 @@ pub struct AuxEnum {
     pub generate_typescript: bool,
 }
 
+#[derive(Debug)]
+pub struct AuxStringEnum {
+    /// The name of this enum
+    pub name: String,
+    /// Whether this enum is public
+    pub public: bool,
+    /// The copied Rust comments to forward to JS
+    pub comments: String,
+    /// A list of variants values
+    pub variant_values: Vec<String>,
+    /// Whether typescript bindings should be generated for this enum.
+    pub generate_typescript: bool,
+}
+
 #[derive(Debug)]
 pub struct AuxStruct {
     /// The name of this struct