Remove slice logic of "commit to wasm"

When adding support for mutable slices I was under the impression that if the
wasm memory was reallocated while we were using it then we'd have to commit the
changes from the original buffer back to the new buffer. What I didn't know,
however, is that once the wasm memory is reallocated then all views into it are
supposed to be defunkt.

It looks like node 9 didn't have this implementation quite right and it appears
fixed in node 10, causing the deleted test here to fail. While this commit does
raise the question of whether this is the right approach to interact with slices
in JS I think the answer is still "yes". The user can always initiate the copy
if need be and that seems strictly better than copying 100% of the time.

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

@@ -1264,60 +1264,6 @@ impl<'a> Context<'a> {
         }
     }
 
-    fn expose_commit_slice_to_wasm(&mut self, ty: VectorKind)
-        -> Result<&'static str, Error>
-    {
-        let gen = |me: &mut Context, name: &'static str, size: usize, get: &str| {
-            me.global(&format!("
-                function {name}(ptr, view) {{
-                    if (view.buffer !== wasm.memory.buffer)
-                        {get}().set(view, ptr / {size});
-                }}
-            ",
-                name = name,
-                size = size,
-                get = get,
-            ));
-            name
-        };
-        match ty {
-            VectorKind::String => bail!("strings cannot be used with mutable slices"),
-            VectorKind::Anyref => bail!("js values cannot be used with mutable slices"),
-            VectorKind::I8 => {
-                self.expose_int8_memory();
-                Ok(gen(self, "commitI8ToWasm", 1, "getInt8Memory"))
-            }
-            VectorKind::U8 => {
-                self.expose_uint8_memory();
-                Ok(gen(self, "commitU8ToWasm", 1, "getUint8Memory"))
-            }
-            VectorKind::I16 => {
-                self.expose_int16_memory();
-                Ok(gen(self, "commitI16ToWasm", 2, "getInt16Memory"))
-            }
-            VectorKind::U16 => {
-                self.expose_uint16_memory();
-                Ok(gen(self, "commitU16ToWasm", 2, "getUint16Memory"))
-            }
-            VectorKind::I32 => {
-                self.expose_int32_memory();
-                Ok(gen(self, "commitI32ToWasm", 4, "getInt32Memory"))
-            }
-            VectorKind::U32 => {
-                self.expose_uint32_memory();
-                Ok(gen(self, "commitU32ToWasm", 4, "getUint32Memory"))
-            }
-            VectorKind::F32 => {
-                self.expose_f32_memory();
-                Ok(gen(self, "commitF32ToWasm", 4, "getFloat32Memory"))
-            }
-            VectorKind::F64 => {
-                self.expose_f64_memory();
-                Ok(gen(self, "commitF64ToWasm", 8, "getFloat64Memory"))
-            }
-        }
-    }
-
     fn expose_get_global_argument(&mut self) -> Result<(), Error> {
         if !self.exposed_globals.insert("get_global_argument") {
             return Ok(());

crates/cli-support/src/js/rust2js.rs

@@ -93,9 +93,6 @@ impl<'a, 'b> Rust2Js<'a, 'b> {
                     wasm.__wbindgen_free({0}, {1} * {size});\
                 ", abi, abi2, size = ty.size()));
                 self.cx.require_internal_export("__wbindgen_free")?;
-            } else if arg.is_mut_ref() {
-                let f = self.cx.expose_commit_slice_to_wasm(ty)?;
-                self.finally(&format!("{}({1}, v{1});", f, abi));
             }
             self.js_arguments.push(format!("v{}", abi));
             return Ok(())