Be sure to generate classes for empty structs

Closes #131

crates/backend/src/ast.rs

@@ -415,6 +415,7 @@ impl Program {
     pub fn shared(&self) -> shared::Program {
         shared::Program {
             exports: self.exports.iter().map(|a| a.shared()).collect(),
+            structs: self.structs.iter().map(|a| a.name.as_ref().to_string()).collect(),
             enums: self.enums.iter().map(|a| a.shared()).collect(),
             imports: self.imports.iter().map(|a| a.shared()).collect(),
             version: shared::version(),

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

@@ -1279,6 +1279,11 @@ impl<'a, 'b> SubContext<'a, 'b> {
         for e in self.program.enums.iter() {
             self.generate_enum(e);
         }
+        for s in self.program.structs.iter() {
+            self.cx.exported_classes
+                .entry(s.clone())
+                .or_insert_with(Default::default);
+        }
     }
 
     pub fn generate_export(&mut self, export: &shared::Export) {

crates/shared/src/lib.rs

@@ -8,6 +8,7 @@ pub struct Program {
     pub exports: Vec<Export>,
     pub enums: Vec<Enum>,
     pub imports: Vec<Import>,
+    pub structs: Vec<String>,
     pub version: String,
     pub schema_version: String,
 }

tests/all/classes.rs

@@ -367,8 +367,6 @@ fn pass_into_js_as_js_class() {
         .test();
 }
 
-
-
 #[test]
 fn constructors() {
     project()
@@ -445,3 +443,33 @@ fn constructors() {
         "#)
         .test();
 }
+
+#[test]
+fn empty_structs() {
+    project()
+        .debug(false)
+        .file("src/lib.rs", r#"
+            #![feature(proc_macro, wasm_custom_section, wasm_import_module)]
+
+            extern crate wasm_bindgen;
+
+            use wasm_bindgen::prelude::*;
+
+            #[wasm_bindgen]
+            pub struct MissingClass {}
+
+            #[wasm_bindgen]
+            pub struct Other {}
+
+            #[wasm_bindgen]
+            impl Other { pub fn return_a_value() -> MissingClass { MissingClass {} } }
+        "#)
+        .file("test.ts", r#"
+            import { Other } from "./out";
+
+            export function test() {
+                Other.return_a_value();
+            }
+        "#)
+        .test();
+}