More user-friendly error message about missing value for `name` attribute in module macro

Update the `[lua_module]` doc

mlua_derive/src/lib.rs

@@ -18,7 +18,14 @@ struct ModuleAttributes {
 impl ModuleAttributes {
     fn parse(&mut self, meta: ParseNestedMeta) -> Result<()> {
         if meta.path.is_ident("name") {
-            self.name = Some(meta.value()?.parse::<LitStr>()?.parse()?);
+            match meta.value() {
+                Ok(value) => {
+                    self.name = Some(value.parse::<LitStr>()?.parse()?);
+                }
+                Err(_) => {
+                    return Err(meta.error(format!("`name` attribute must have a value")));
+                }
+            }
         } else {
             return Err(meta.error("unsupported module attribute"));
         }

src/lib.rs

@@ -230,6 +230,17 @@ pub use mlua_derive::chunk;
 ///
 /// Internally in the code above the compiler defines C function `luaopen_my_module`.
 ///
+/// You can also pass options to the attribute:
+///
+/// name - name of the module, defaults to the name of the function
+///
+/// ```ignore
+/// #[mlua::lua_module(name = "alt_module")]
+/// fn my_module(lua: &Lua) -> Result<Table> {
+///     ...
+/// }
+/// ```
+///
 #[cfg(any(feature = "module", docsrs))]
 #[cfg_attr(docsrs, doc(cfg(feature = "module")))]
 pub use mlua_derive::lua_module;