Reimplement anyref processing and passes

This commit reimplements the `anyref` transformation pass tasked with
taking raw rustc output and enhancing the module to use `anyref`. This
was disabled in the previous commits during refactoring, and now the
pass is re-enabled in the manner originally intended.

Instead of being tangled up in the `js/mod.rs` pass, the anyref
transformation now happens locally within one module,
`cli-support/src/anyref.rs`, which exclusively uses the output of the
`webidl` module which produces a WebIDL bindings section as well as an
auxiliary wasm-bindgen specific section. This makes the anyref transform
much more straightforward and local, ensuring that it doesn't propagate
elsewhere and can be a largely local concern during the transformation.

The main addition needed to support this pass was detailed knowledge of
the ABI of a `Descriptor`. This knowledge is already implicitly
hardcoded in `js2rust.rs` and `rust2js.rs` through the ABI shims
generated. This was previously used for the anyref transformation to
piggy-back what was already there, but as a separate pass we are unable
to reuse the knowledge in the binding generator.

Instead `Descriptor` now has two dedicated methods describing the
various ABI properties of a type. This is then asserted to be correct
(all the time) when processing bindings, ensuring that the two are kept
in sync.

crates/anyref-xform/src/lib.rs

@@ -20,6 +20,7 @@ use std::cmp;
 use std::collections::{BTreeMap, HashMap, HashSet};
 use std::mem;
 use walrus::ir::*;
+use walrus::{ExportId, ImportId};
 use walrus::{FunctionId, GlobalId, InitExpr, Module, TableId, ValType};
 
 // must be kept in sync with src/lib.rs and ANYREF_HEAP_START
@@ -32,8 +33,8 @@ pub struct Context {
     // Functions within the module that we're gonna be wrapping, organized by
     // type. The `Function` contains information about what arguments/return
     // values in the function signature should turn into anyref.
-    imports: HashMap<String, HashMap<String, Function>>,
+    imports: HashMap<ImportId, Function>,
-    exports: HashMap<String, Function>,
+    exports: HashMap<ExportId, Function>,
     elements: BTreeMap<u32, (u32, Function)>,
 
     // When wrapping closures with new shims, this is the index of the next
@@ -42,9 +43,6 @@ pub struct Context {
 
     // The anyref table we'll be using, injected after construction
     table: Option<TableId>,
-
-    // Whether or not the transformation will actually be run at the end
-    pub enabled: bool,
 }
 
 struct Transform<'a> {
@@ -68,7 +66,6 @@ struct Transform<'a> {
 }
 
 struct Function {
-    name: String,
     // A map of argument index to whether it's an owned or borrowed anyref
     // (owned = true)
     args: HashMap<usize, bool>,
@@ -87,10 +84,6 @@ impl Context {
     /// large the function table is so we know what indexes to hand out when
     /// we're appending entries.
     pub fn prepare(&mut self, module: &mut Module) -> Result<(), Error> {
-        if !self.enabled {
-            return Ok(());
-        }
-
         // Figure out what the maximum index of functions pointers are. We'll
         // be adding new entries to the function table later (maybe) so
         // precalculate this ahead of time.
@@ -118,19 +111,13 @@ impl Context {
     /// transformed. The actual transformation happens later during `run`.
     pub fn import_xform(
         &mut self,
-        module: &str,
+        id: ImportId,
-        name: &str,
         anyref: &[(usize, bool)],
         ret_anyref: bool,
     ) -> &mut Self {
-        if !self.enabled {
+        if let Some(f) = self.function(anyref, ret_anyref) {
-            return self;
+            self.imports.insert(id, f);
         }
-        let f = self.function(name, anyref, ret_anyref);
-        self.imports
-            .entry(module.to_string())
-            .or_insert_with(Default::default)
-            .insert(name.to_string(), f);
         self
     }
 
@@ -138,15 +125,13 @@ impl Context {
     /// transformed. The actual transformation happens later during `run`.
     pub fn export_xform(
         &mut self,
-        name: &str,
+        id: ExportId,
         anyref: &[(usize, bool)],
         ret_anyref: bool,
     ) -> &mut Self {
-        if !self.enabled {
+        if let Some(f) = self.function(anyref, ret_anyref) {
-            return self;
+            self.exports.insert(id, f);
         }
-        let f = self.function(name, anyref, ret_anyref);
-        self.exports.insert(name.to_string(), f);
         self
     }
 
@@ -158,34 +143,26 @@ impl Context {
         idx: u32,
         anyref: &[(usize, bool)],
         ret_anyref: bool,
-    ) -> u32 {
+    ) -> Option<u32> {
-        if !self.enabled {
+        self.function(anyref, ret_anyref).map(|f| {
-            return idx;
-        }
-        let name = format!("closure{}", idx);
-        let f = self.function(&name, anyref, ret_anyref);
             let ret = self.next_element;
             self.next_element += 1;
             self.elements.insert(ret, (idx, f));
             ret
+        })
     }
 
-    fn function(&self, name: &str, anyref: &[(usize, bool)], ret_anyref: bool) -> Function {
+    fn function(&self, anyref: &[(usize, bool)], ret_anyref: bool) -> Option<Function> {
-        Function {
+        if !ret_anyref && anyref.len() == 0 {
-            name: name.to_string(),
+            return None;
+        }
+        Some(Function {
             args: anyref.iter().cloned().collect(),
             ret_anyref,
-        }
+        })
-    }
-
-    pub fn anyref_table_id(&self) -> TableId {
-        self.table.unwrap()
     }
 
     pub fn run(&mut self, module: &mut Module) -> Result<(), Error> {
-        if !self.enabled {
-            return Ok(());
-        }
         let table = self.table.unwrap();
 
         // Inject a stack pointer global which will be used for managing the
@@ -261,9 +238,7 @@ impl Transform<'_> {
 
         // Perform transformations of imports, exports, and function pointers.
         self.process_imports(module);
-        for m in self.cx.imports.values() {
+        assert!(self.cx.imports.is_empty());
-            assert!(m.is_empty());
-        }
         self.process_exports(module);
         assert!(self.cx.exports.is_empty());
         self.process_elements(module)?;
@@ -333,20 +308,15 @@ impl Transform<'_> {
                 walrus::ImportKind::Function(f) => f,
                 _ => continue,
             };
-            let import = {
+            let func = match self.cx.imports.remove(&import.id()) {
-                let entries = match self.cx.imports.get_mut(&import.module) {
                 Some(s) => s,
                 None => continue,
             };
-                match entries.remove(&import.name) {
-                    Some(s) => s,
-                    None => continue,
-                }
-            };
 
             let shim = self.append_shim(
                 f,
-                import,
+                &import.name,
+                func,
                 &mut module.types,
                 &mut module.funcs,
                 &mut module.locals,
@@ -356,29 +326,25 @@ impl Transform<'_> {
     }
 
     fn process_exports(&mut self, module: &mut Module) {
-        let mut new_exports = Vec::new();
+        // let mut new_exports = Vec::new();
-        for export in module.exports.iter() {
+        for export in module.exports.iter_mut() {
             let f = match export.item {
                 walrus::ExportItem::Function(f) => f,
                 _ => continue,
             };
-            let function = match self.cx.exports.remove(&export.name) {
+            let function = match self.cx.exports.remove(&export.id()) {
                 Some(s) => s,
                 None => continue,
             };
             let shim = self.append_shim(
                 f,
+                &export.name,
                 function,
                 &mut module.types,
                 &mut module.funcs,
                 &mut module.locals,
             );
-            new_exports.push((export.name.to_string(), shim, export.id()));
+            export.item = shim.into();
-        }
-
-        for (name, shim, old_id) in new_exports {
-            module.exports.add(&name, shim);
-            module.exports.delete(old_id);
         }
     }
 
@@ -402,6 +368,7 @@ impl Transform<'_> {
             let target = kind.elements[idx as usize].unwrap();
             let shim = self.append_shim(
                 target,
+                &format!("closure{}", idx),
                 function,
                 &mut module.types,
                 &mut module.funcs,
@@ -422,6 +389,7 @@ impl Transform<'_> {
     fn append_shim(
         &mut self,
         shim_target: FunctionId,
+        name: &str,
         mut func: Function,
         types: &mut walrus::ModuleTypes,
         funcs: &mut walrus::ModuleFunctions,
@@ -625,7 +593,7 @@ impl Transform<'_> {
         // nice name for debugging and then we're good to go!
         let expr = builder.with_side_effects(before, result, after);
         let id = builder.finish_parts(shim_ty, params, vec![expr], types, funcs);
-        let name = format!("{}_anyref_shim", func.name);
+        let name = format!("{}_anyref_shim", name);
         funcs.get_mut(id).name = Some(name);
         self.shims.insert(id);
         return id;

crates/cli-support/src/anyref.rs

@@ -0,0 +1,87 @@
+use crate::descriptor::Function;
+use crate::webidl::{ImportBinding, WasmBindgenAux, WebidlCustomSection, AuxImport};
+use failure::Error;
+use std::collections::HashSet;
+use walrus::Module;
+
+pub fn process(module: &mut Module) -> Result<(), Error> {
+    let mut cfg = wasm_bindgen_anyref_xform::Context::default();
+    cfg.prepare(module)?;
+    let bindings = module
+        .customs
+        .get_typed::<WebidlCustomSection>()
+        .expect("webidl custom section should exist");
+
+    for (export, binding) in bindings.exports.iter() {
+        let (args, ret) = extract_anyrefs(binding);
+        cfg.export_xform(*export, &args, ret);
+    }
+
+    for (import, kind) in bindings.imports.iter() {
+        let binding = match kind {
+            ImportBinding::Function(f) => f,
+            ImportBinding::Constructor(f) => f,
+            ImportBinding::Method(f) => f,
+        };
+        let (args, ret) = extract_anyrefs(binding);
+        cfg.import_xform(*import, &args, ret);
+    }
+
+    let aux = module
+        .customs
+        .get_typed_mut::<WasmBindgenAux>()
+        .expect("webidl custom section should exist");
+    for import in aux.import_map.values_mut() {
+        let closure = match import {
+            AuxImport::Closure(f) => f,
+            _ => continue,
+        };
+        let (args, ret) = extract_anyrefs(&closure.function);
+        if let Some(new) = cfg.table_element_xform(closure.shim_idx, &args, ret) {
+            closure.shim_idx = new;
+        }
+    }
+
+    cfg.run(module)?;
+    walrus::passes::gc::run(module);
+
+    // The GC pass above may end up removing some imported intrinsics. For
+    // example `__wbindgen_object_clone_ref` is no longer needed after the
+    // anyref pass. Make sure to delete the associated metadata for those
+    // intrinsics so we don't try to access stale intrinsics later on.
+    let remaining_imports = module
+        .imports
+        .iter()
+        .map(|i| i.id())
+        .collect::<HashSet<_>>();
+    module
+        .customs
+        .get_typed_mut::<WebidlCustomSection>()
+        .expect("webidl custom section should exist")
+        .imports
+        .retain(|id, _| remaining_imports.contains(id));
+    module
+        .customs
+        .get_typed_mut::<WasmBindgenAux>()
+        .expect("wasm-bindgen aux section should exist")
+        .import_map
+        .retain(|id, _| remaining_imports.contains(id));
+    Ok(())
+}
+
+fn extract_anyrefs(f: &Function) -> (Vec<(usize, bool)>, bool) {
+    let mut args = Vec::new();
+    let mut cur = 0;
+    if f.ret.abi_returned_through_pointer() {
+        cur += 1;
+    }
+    for arg in f.arguments.iter() {
+        if arg.is_anyref() {
+            args.push((cur, true));
+        } else if arg.is_ref_anyref() {
+            args.push((cur, false));
+        }
+        cur += arg.abi_arg_count();
+    }
+    (args, f.ret.is_anyref())
+}

crates/cli-support/src/descriptor.rs

@@ -292,6 +292,83 @@ impl Descriptor {
             _ => false,
         }
     }
+
+    pub fn abi_returned_through_pointer(&self) -> bool {
+        if self.vector_kind().is_some() {
+            return true;
+        }
+        if self.get_64().is_some() {
+            return true;
+        }
+        match self {
+            Descriptor::Option(inner) => match &**inner {
+                Descriptor::Anyref
+                | Descriptor::RustStruct(_)
+                | Descriptor::Enum { .. }
+                | Descriptor::Char
+                | Descriptor::Boolean
+                | Descriptor::I8
+                | Descriptor::U8
+                | Descriptor::I16
+                | Descriptor::U16 => false,
+                _ => true,
+            },
+            _ => false,
+        }
+    }
+
+    pub fn abi_arg_count(&self) -> usize {
+        if let Descriptor::Option(inner) = self {
+            if inner.get_64().is_some() {
+                return 4;
+            }
+            if let Descriptor::Ref(inner) = &**inner {
+                match &**inner {
+                    Descriptor::Anyref => return 1,
+                    _ => {}
+                }
+            }
+        }
+        if self.stack_closure().is_some() {
+            return 2;
+        }
+        if self.abi_returned_through_pointer() {
+            2
+        } else {
+            1
+        }
+    }
+
+    pub fn assert_abi_return_correct(&self, before: usize, after: usize) {
+        if before != after {
+            assert_eq!(
+                before + 1,
+                after,
+                "abi_returned_through_pointer wrong for {:?}",
+                self,
+            );
+            assert!(
+                self.abi_returned_through_pointer(),
+                "abi_returned_through_pointer wrong for {:?}",
+                self,
+            );
+        } else {
+            assert!(
+                !self.abi_returned_through_pointer(),
+                "abi_returned_through_pointer wrong for {:?}",
+                self,
+            );
+        }
+    }
+
+    pub fn assert_abi_arg_correct(&self, before: usize, after: usize) {
+        assert_eq!(
+            before + self.abi_arg_count(),
+            after,
+            "abi_arg_count wrong for {:?}",
+            self,
+        );
+    }
 }
 
 fn get(a: &mut &[u32]) -> u32 {

crates/cli-support/src/js/js2rust.rs

@@ -68,15 +68,6 @@ pub struct Js2Rust<'a, 'b: 'a> {
     /// The string value here is the class that this should be a constructor
     /// for.
     constructor: Option<String>,
-
-    /// metadata for anyref transformations
-    anyref_args: Vec<(usize, bool)>,
-    ret_anyref: bool,
-}
-
-pub enum ExportedShim<'a> {
-    Named(&'a str),
-    TableElement(&'a mut u32),
 }
 
 impl<'a, 'b> Js2Rust<'a, 'b> {
@@ -92,8 +83,6 @@ impl<'a, 'b> Js2Rust<'a, 'b> {
             ret_ty: String::new(),
             ret_expr: String::new(),
             constructor: None,
-            anyref_args: Vec::new(),
-            ret_anyref: false,
         }
     }
 
@@ -104,17 +93,26 @@ impl<'a, 'b> Js2Rust<'a, 'b> {
         function: &Function,
         opt_arg_names: &Option<Vec<String>>,
     ) -> Result<&mut Self, Error> {
-        if let Some(arg_names) = opt_arg_names {
+        let arg_names = match opt_arg_names {
+            Some(arg_names) => arg_names.iter().map(|s| Some(s.as_str())).collect(),
+            None => vec![None; function.arguments.len()],
+        };
         assert_eq!(arg_names.len(), function.arguments.len());
         for (arg, arg_name) in function.arguments.iter().zip(arg_names) {
-                self.argument(arg, arg_name.as_str())?;
+            // Process the function argument and assert that the metadata about
-            }
+            // the number of arguments on the Rust side required is correct.
-        } else {
+            let before = self.rust_arguments.len();
-            for arg in function.arguments.iter() {
+            self.argument(arg, arg_name)?;
-                self.argument(arg, None)?;
+            arg.assert_abi_arg_correct(before, self.rust_arguments.len());
-            }
         }
+
+        // Process the return argument, and assert that the metadata returned
+        // about the descriptor is indeed correct.
+        let before = self.rust_arguments.len();
         self.ret(&function.ret)?;
+        function
+            .ret
+            .assert_abi_return_correct(before, self.rust_arguments.len());
         Ok(self)
     }
 
@@ -181,12 +179,9 @@ impl<'a, 'b> Js2Rust<'a, 'b> {
         ret
     }
 
-    pub fn argument<'c, I>(&mut self, arg: &Descriptor, opt_arg_name: I) -> Result<&mut Self, Error>
+    fn argument(&mut self, arg: &Descriptor, arg_name: Option<&str>) -> Result<&mut Self, Error> {
-    where
-        I: Into<Option<&'c str>>,
-    {
         let i = self.arg_idx;
-        let name = self.abi_arg(opt_arg_name.into());
+        let name = self.abi_arg(arg_name);
 
         let (arg, optional) = match arg {
             Descriptor::Option(t) => (&**t, true),
@@ -252,7 +247,6 @@ impl<'a, 'b> Js2Rust<'a, 'b> {
                     self.rust_arguments
                         .push(format!("isLikeNone({0}) ? 0 : addToAnyrefTable({0})", name));
                 } else {
-                    self.anyref_args.push((self.rust_arguments.len(), true));
                     self.rust_arguments.push(name);
                 }
             } else {
@@ -449,7 +443,6 @@ impl<'a, 'b> Js2Rust<'a, 'b> {
             self.js_arguments
                 .push(JsArgument::required(name.clone(), "any".to_string()));
             if self.cx.config.anyref {
-                self.anyref_args.push((self.rust_arguments.len(), false));
                 self.rust_arguments.push(name);
             } else {
                 // the "stack-ful" nature means that we're always popping from the
@@ -492,7 +485,7 @@ impl<'a, 'b> Js2Rust<'a, 'b> {
         Ok(self)
     }
 
-    pub fn ret(&mut self, ty: &Descriptor) -> Result<&mut Self, Error> {
+    fn ret(&mut self, ty: &Descriptor) -> Result<&mut Self, Error> {
         if let Some(name) = ty.rust_struct() {
             match &self.constructor {
                 Some(class) if class == name => {
@@ -566,7 +559,6 @@ impl<'a, 'b> Js2Rust<'a, 'b> {
         if ty.is_anyref() {
             self.ret_ty = "any".to_string();
             self.ret_expr = format!("return {};", self.cx.take_object("RET"));
-            self.ret_anyref = true;
             return Ok(self);
         }
 
@@ -784,12 +776,7 @@ impl<'a, 'b> Js2Rust<'a, 'b> {
     /// Returns two strings, the first of which is the JS expression for the
     /// generated function shim and the second is a TypeScript signature of the
     /// JS expression.
-    pub fn finish(
+    pub fn finish(&mut self, prefix: &str, invoc: &str) -> (String, String, String) {
-        &mut self,
-        prefix: &str,
-        invoc: &str,
-        exported_shim: ExportedShim,
-    ) -> (String, String, String) {
         let js_args = self
             .js_arguments
             .iter()
@@ -854,23 +841,6 @@ impl<'a, 'b> Js2Rust<'a, 'b> {
         }
         ts.push(';');
 
-        if self.ret_anyref || self.anyref_args.len() > 0 {
-            match exported_shim {
-                ExportedShim::Named(name) => {
-                    self.cx
-                        .anyref
-                        .export_xform(name, &self.anyref_args, self.ret_anyref);
-                }
-                ExportedShim::TableElement(idx) => {
-                    *idx = self.cx.anyref.table_element_xform(
-                        *idx,
-                        &self.anyref_args,
-                        self.ret_anyref,
-                    );
-                }
-            }
-        }
-
         (js, ts, self.js_doc_comments())
     }
 

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

@@ -2,7 +2,7 @@ mod js2rust;
 mod rust2js;
 
 use crate::descriptor::VectorKind;
-use crate::js::js2rust::{ExportedShim, Js2Rust};
+use crate::js::js2rust::Js2Rust;
 use crate::js::rust2js::Rust2Js;
 use crate::webidl::{AuxEnum, AuxExport, AuxExportKind, AuxImport, AuxStruct};
 use crate::webidl::{JsImport, JsImportName, WasmBindgenAux, WebidlCustomSection};
@@ -47,8 +47,6 @@ pub struct Context<'a> {
     /// A map of the name of npm dependencies we've loaded so far to the path
     /// they're defined in as well as their version specification.
     pub npm_dependencies: HashMap<String, (PathBuf, String)>,
-
-    pub anyref: wasm_bindgen_anyref_xform::Context,
 }
 
 #[derive(Default)]
@@ -99,7 +97,6 @@ impl<'a> Context<'a> {
             module,
             function_table_needed: false,
             memory,
-            anyref: Default::default(),
             npm_dependencies: Default::default(),
         })
     }
@@ -192,13 +189,6 @@ impl<'a> Context<'a> {
         // `__wrap` and such.
         self.write_classes()?;
 
-        // And now that we're almost ready, run the final "anyref" pass. This is
-        // where we transform a wasm module which doesn't actually use `anyref`
-        // anywhere to using the type internally. The transformation here is
-        // based off all the previous data we've collected so far for each
-        // import/export listed.
-        // self.anyref.run(self.module)?;
-
         // We're almost done here, so we can delete any internal exports (like
         // `__wbindgen_malloc`) if none of our JS glue actually needed it.
         self.unexport_unused_internal_exports();
@@ -1794,9 +1784,17 @@ impl<'a> Context<'a> {
         if !self.should_write_global("anyref_table") {
             return;
         }
-        self.module
+        let table = self
-            .exports
+            .module
-            .add("__wbg_anyref_table", self.anyref.anyref_table_id());
+            .tables
+            .iter()
+            .find(|t| match t.kind {
+                walrus::TableKind::Anyref(_) => true,
+                _ => false,
+            })
+            .expect("failed to find anyref table in module")
+            .id();
+        self.module.exports.add("__wbg_anyref_table", table);
     }
 
     fn expose_add_to_anyref_table(&mut self) -> Result<(), Error> {
@@ -1878,11 +1876,7 @@ impl<'a> Context<'a> {
             AuxExportKind::Function(name) => {
                 let (js, ts, js_doc) = Js2Rust::new(&name, self)
                     .process(&descriptor, &export.arg_names)?
-                    .finish(
+                    .finish("function", &format!("wasm.{}", wasm_name));
-                        "function",
-                        &format!("wasm.{}", wasm_name),
-                        ExportedShim::Named(&wasm_name),
-                    );
                 self.export(
                     &name,
                     &js,
@@ -1897,11 +1891,7 @@ impl<'a> Context<'a> {
                 let (js, ts, raw_docs) = Js2Rust::new("constructor", self)
                     .constructor(Some(&class))
                     .process(&descriptor, &export.arg_names)?
-                    .finish(
+                    .finish("", &format!("wasm.{}", wasm_name));
-                        "",
-                        &format!("wasm.{}", wasm_name),
-                        ExportedShim::Named(&wasm_name),
-                    );
                 let exported = require_class(&mut self.exported_classes, class);
                 if exported.has_constructor {
                     bail!("found duplicate constructor for class `{}`", class);
@@ -1924,11 +1914,9 @@ impl<'a> Context<'a> {
                         j2r.method(false);
                     }
                 }
-                let (js, ts, raw_docs) = j2r.process(&descriptor, &export.arg_names)?.finish(
+                let (js, ts, raw_docs) = j2r
-                    "",
+                    .process(&descriptor, &export.arg_names)?
-                    &format!("wasm.{}", wasm_name),
+                    .finish("", &format!("wasm.{}", wasm_name));
-                    ExportedShim::Named(&wasm_name),
-                );
                 let ret_ty = j2r.ret_ty.clone();
                 let exported = require_class(&mut self.exported_classes, class);
                 let docs = format_doc_comments(&export.comments, Some(raw_docs));

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

@@ -1,6 +1,5 @@
 use crate::descriptor::Descriptor;
 use crate::intrinsic::Intrinsic;
-use crate::js::js2rust::ExportedShim;
 use crate::js::{Context, Js2Rust};
 use crate::webidl::{AuxImport, AuxValue, ImportBinding};
 use failure::{bail, Error};
@@ -119,9 +118,19 @@ impl<'a, 'b> Rust2Js<'a, 'b> {
             }
         };
         for arg in function.arguments.iter() {
+            // Process the function argument and assert that the metadata about
+            // the number of arguments on the Rust side required is correct.
+            let before = self.shim_arguments.len();
             self.argument(arg)?;
+            arg.assert_abi_arg_correct(before, self.shim_arguments.len());
         }
+        // Process the return argument, and assert that the metadata returned
+        // about the descriptor is indeed correct.
+        let before = self.shim_arguments.len();
         self.ret(&function.ret)?;
+        function
+            .ret
+            .assert_abi_return_correct(before, self.shim_arguments.len());
         Ok(self)
     }
 
@@ -308,7 +317,6 @@ impl<'a, 'b> Rust2Js<'a, 'b> {
 
         if let Some((f, mutable)) = arg.stack_closure() {
             let arg2 = self.shim_argument();
-            let mut shim = f.shim_idx;
             let (js, _ts, _js_doc) = {
                 let mut builder = Js2Rust::new("", self.cx);
                 if mutable {
@@ -320,11 +328,10 @@ impl<'a, 'b> Rust2Js<'a, 'b> {
                 } else {
                     builder.rust_argument("this.a");
                 }
-                builder.rust_argument("this.b").process(f, &None)?.finish(
+                builder
-                    "function",
+                    .rust_argument("this.b")
-                    "this.f",
+                    .process(f, &None)?
-                    ExportedShim::TableElement(&mut shim),
+                    .finish("function", "this.f")
-                )
             };
             self.cx.function_table_needed = true;
             self.global_idx();
@@ -338,7 +345,7 @@ impl<'a, 'b> Rust2Js<'a, 'b> {
                 abi,
                 arg2,
                 js = js,
-                idx = shim,
+                idx = f.shim_idx,
             ));
             self.finally(&format!("cb{0}.a = cb{0}.b = 0;", abi));
             self.js_arguments.push(format!("cb{0}.bind(cb{0})", abi));
@@ -741,7 +748,6 @@ impl<'a, 'b> Rust2Js<'a, 'b> {
                 assert!(self.style == Style::Function);
                 assert!(!variadic);
                 assert_eq!(self.js_arguments.len(), 3);
-                let mut shim = closure.shim_idx;
                 let (js, _ts, _js_doc) = {
                     let mut builder = Js2Rust::new("", self.cx);
 
@@ -777,11 +783,9 @@ impl<'a, 'b> Rust2Js<'a, 'b> {
                             .finally("this.a = 0;")
                             .finally("}");
                     }
-                    builder.process(&closure.function, &None)?.finish(
+                    builder
-                        "function",
+                        .process(&closure.function, &None)?
-                        "f",
+                        .finish("function", "f")
-                        ExportedShim::TableElement(&mut shim),
-                    )
                 };
                 self.cx.function_table_needed = true;
                 let body = format!(
@@ -795,7 +799,7 @@ impl<'a, 'b> Rust2Js<'a, 'b> {
                         let real = cb.bind(cb);
                         real.original = cb;
                     ",
-                    shim,
+                    closure.shim_idx,
                     closure.dtor_idx,
                     &self.js_arguments[1],
                     js,
@@ -978,32 +982,6 @@ impl<'a, 'b> Rust2Js<'a, 'b> {
         ret.push_str(&invoc);
         ret.push_str("\n}\n");
 
-        // if self.ret_anyref || self.anyref_args.len() > 0 {
-        //     // Some return values go at the the beginning of the argument list
-        //     // (they force a return pointer). Handle that here by offsetting all
-        //     // our arg indices by one, but throw in some sanity checks for if
-        //     // this ever changes.
-        //     if let Some(start) = self.shim_arguments.get(0) {
-        //         if start == "ret" {
-        //             assert!(!self.ret_anyref);
-        //             if let Some(next) = self.shim_arguments.get(1) {
-        //                 assert_eq!(next, "arg0");
-        //             }
-        //             for (idx, _) in self.anyref_args.iter_mut() {
-        //                 *idx += 1;
-        //             }
-        //         } else {
-        //             assert_eq!(start, "arg0");
-        //         }
-        //     }
-        //     self.cx.anyref.import_xform(
-        //         "__wbindgen_placeholder__",
-        //         shim,
-        //         &self.anyref_args,
-        //         self.ret_anyref,
-        //     );
-        // }
-
         Ok(ret)
     }
 

crates/cli-support/src/lib.rs

@@ -9,6 +9,7 @@ use std::path::{Path, PathBuf};
 use std::str;
 use walrus::Module;
 
+mod anyref;
 mod decode;
 mod intrinsic;
 mod descriptor;
@@ -316,6 +317,10 @@ impl Bindgen {
         // supports that aren't covered by WebIDL bindings.
         webidl::process(&mut module)?;
 
+        if self.anyref {
+            anyref::process(&mut module)?;
+        }
+
         // If we're in a testing mode then remove the start function since we
         // shouldn't execute it.
         if !self.emit_start {
@@ -326,8 +331,6 @@ impl Bindgen {
         // shim generation which will actually generate JS for all this.
         let (js, ts) = {
             let mut cx = js::Context::new(&mut module, self)?;
-            cx.anyref.enabled = self.anyref;
-            cx.anyref.prepare(cx.module)?;
 
             let aux = cx.module.customs.delete_typed::<webidl::WasmBindgenAux>()
                 .expect("aux section should be present");