ReferenceError when resource has no functions #221

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1. MendyBerger commented on Jun 12, 2025

   

   MendyBerger

   on Jun 12, 2025

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   Running into the same issue with wasi:graphics-context/graphics-context#abstract-buffer.

   It either gives a similar error to the one posted by the OP or sometimes even just hangs indefinitely without any errors.

   Adding a simple foo: func(); to the resource gets it to work correctly.
2. ericgregory commented on Mar 19, 2026

   

   ericgregory

   on Mar 19, 2026

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   Confirming this bug in 0.19.4-rc.1 with a different WASI interface: wasi:sockets/network (wasi:sockets@0.2.3).

   wasi:sockets/network defines a single network resource with no methods. It is referenced by wasi:sockets/instance-network (instanceNetwork() returns a network) and by wasi:sockets/tcp (socket methods take borrow<network>). Neither of those interfaces defines the class — they just use it — so the class is never emitted and any guest code that calls instanceNetwork() or binds/connects a TCP socket throws at runtime:

   ReferenceError: import_network_0_2_3$Network is not defined
   

   Minimal reproducer

   WIT world:

   package example:sockets-demo@0.1.0;
   
   world sockets-demo {
     import wasi:sockets/instance-network@0.2.3;
     import wasi:sockets/tcp@0.2.3;
     import wasi:sockets/tcp-create-socket@0.2.3;
     import wasi:io/poll@0.2.0;
     export wasi:cli/run@0.2.0;
   }

   TypeScript guest:

   import { instanceNetwork } from 'wasi:sockets/instance-network@0.2.3';
   import { createTcpSocket } from 'wasi:sockets/tcp-create-socket@0.2.3';
   
   export const run = {
     run(): void {
       const network = instanceNetwork(); // throws: import_network_0_2_3$Network is not defined
       const socket = createTcpSocket('ipv4');
       // ...
     },
   };

   The generated bindings emit finalizationRegistry_import$network_0_2_3$network = new FinalizationRegistry(...) but never class import_network_0_2_3$Network { ... }. The class is only generated when the owning interface (wasi:sockets/network) has at least one callable function — since it has none, the class is skipped entirely.

   Root cause

   The issue is in spidermonkey-embedding-splicer. The class-generation code path is gated on the interface having callable functions; resource types in function-less interfaces fall through without a class definition. The class should be emitted for every imported resource, regardless of whether the owning interface has any callable functions.

   JS-side workaround patch

   While the right fix is in the splicer, here is a patch applied to componentize.js that works around the issue. It scans the generated bindings for finalization registries with no matching class and injects minimal class definitions after symbolDispose is declared:

   // After spliceBindings() — inject missing resource classes
   {
     const registryRe = /finalizationRegistry_import\$([^$]+)\$([^\s=]+) = new FinalizationRegistry/g;
     let m;
     const missingClasses = [];
     while ((m = registryRe.exec(jsBindings)) !== null) {
       const iface = m[1];
       const rsc = m[2];
       const className = `import_${iface}$${rsc.charAt(0).toUpperCase()}${rsc.slice(1)}`;
       if (!jsBindings.includes(`class ${className}`)) {
         missingClasses.push({ iface, rsc, className });
       }
     }
     if (missingClasses.length > 0) {
       const injected = missingClasses.map(({ iface, rsc, className }) =>
         `class ${className} {\n` +
         `  [symbolDispose]() {\n` +
         `    finalizationRegistry_import$${iface}$${rsc}.unregister(this);\n` +
         `    $resource_import$${iface}$drop$${rsc}(this[symbolRscHandle]);\n` +
         `    this[symbolRscHandle] = undefined;\n` +
         `  }\n` +
         `}\n`
       ).join('');
       jsBindings = jsBindings.replace(
         '\nconst symbolDispose = Symbol.dispose || Symbol.for(\'dispose\');',
         '\nconst symbolDispose = Symbol.dispose || Symbol.for(\'dispose\');\n' + injected,
       );
     }
   }

   This was developed while building a TypeScript wasmCloud service-and-component template that uses wasi:sockets for intra-workload TCP communication: wasmCloud/typescript#583
3. carsonfarmer commented on Sep 26, 2026

   

   carsonfarmer

   on Sep 26, 2026

   Last edited by carsonfarmer

   Contributor

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   I reproduced this on 0.23.0 and 4d812f5. #357 fixes the missing class generation and adds a regression for returning, borrowing and disposing of a resource with no methods.
4. andreiltd

   closed this as completedin #357on Oct 19, 2026