Eagerly cached TypedArray objects cause circular dependency for bundler modes

[ishitatsuyuki]

Describe the Bug

Descriptions like cachedInt32Memory0 = new Int32Array(wasm.memory.buffer); creates a circular dependency between the bg module and the instantiation wrapper created by bundlers, because the wrapper needs to import the bg module to pass the exports to WebAssembly.instantiate's second argument (importObject), while this depends on wasm.memory which is initialized after the instantiation is complete.

Steps to Reproduce

I haven't isolated the reproduction yet, because it seems to depend on the use of certain ArrayBuffer related function calls.

I'm using https://github.com/Menci/vite-plugin-wasm, but at a quick glance Webpack should be doing the implementation in basically the same manner.

Errors

Uncaught ReferenceError: can't access lexical declaration 'memory' before initialization
    <anonymous> http://localhost:3000/rust/pkg/wasm_bg.js?t=1655889863398:318

Proposed modification

Just make it lazy.

diff --git a/crates/cli-support/src/js/mod.rs b/crates/cli-support/src/js/mod.rs
index 8ca6a854..86dda79c 100644
--- a/crates/cli-support/src/js/mod.rs
+++ b/crates/cli-support/src/js/mod.rs
@@ -607,10 +607,9 @@ impl<'a> Context<'a> {
             for kind in views {
                 writeln!(
                     out,
-                    "cached{kind}Memory{num} = new {kind}Array(wasm.{mem}.buffer);",
+                    "cached{kind}Memory{num} = new {kind}Array();",
                     kind = kind,
                     num = num,
-                    mem = mem,
                 )
                 .unwrap()
             }

[gthb]

In my case (running in Node.js 16, importing the wasm-bindgen module as an ES module, having run wasm-pack with --target bundler and changed the generated package.json to have "type": "module" and a "main" attribute), the problem manifested as:

ReferenceError: memory is not defined

(just adding that comment to make this issue easier for others to find than it was for me! 😊)