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//! Functions within a wasm module.
use std::cmp;
use std::collections::BTreeMap;
use anyhow::{bail, Context};
use wasm_encoder::Encode;
use wasmparser::{FuncValidator, FunctionBody, Range, ValidatorResources};
#[cfg(feature = "parallel")]
use rayon::prelude::*;
mod local_function;
use crate::emit::{Emit, EmitContext};
use crate::error::Result;
use crate::ir::InstrLocId;
use crate::module::imports::ImportId;
use crate::module::Module;
use crate::parse::IndicesToIds;
use crate::tombstone_arena::{Id, Tombstone, TombstoneArena};
use crate::ty::TypeId;
use crate::ty::ValType;
use crate::{ExportItem, FunctionBuilder, InstrSeqBuilder, LocalId, Memory, MemoryId};
pub use self::local_function::LocalFunction;
/// A function identifier.
pub type FunctionId = Id<Function>;
/// Parameter(s) to a function
pub type FuncParams = Vec<ValType>;
/// Result(s) of a given function
pub type FuncResults = Vec<ValType>;
/// A wasm function.
///
/// Either defined locally or externally and then imported; see `FunctionKind`.
#[derive(Debug)]
pub struct Function {
// NB: Not public so that it can't get out of sync with the arena that this
// function lives within.
id: FunctionId,
/// The kind of function this is.
pub kind: FunctionKind,
/// An optional name associated with this function
pub name: Option<String>,
}
impl Tombstone for Function {
fn on_delete(&mut self) {
let ty = self.ty();
self.kind = FunctionKind::Uninitialized(ty);
self.name = None;
}
}
impl Function {
fn new_uninitialized(id: FunctionId, ty: TypeId) -> Function {
Function {
id,
kind: FunctionKind::Uninitialized(ty),
name: None,
}
}
/// Get this function's identifier.
pub fn id(&self) -> FunctionId {
self.id
}
/// Get this function's type's identifier.
pub fn ty(&self) -> TypeId {
match &self.kind {
FunctionKind::Local(l) => l.ty(),
FunctionKind::Import(i) => i.ty,
FunctionKind::Uninitialized(t) => *t,
}
}
}
/// The local- or external-specific bits of a function.
#[derive(Debug)]
pub enum FunctionKind {
/// An externally defined, imported wasm function.
Import(ImportedFunction),
/// A locally defined wasm function.
Local(LocalFunction),
/// A locally defined wasm function that we haven't parsed yet (but have
/// reserved its id and associated it with its original input wasm module
/// index). This should only exist within
/// `ModuleFunctions::add_local_functions`.
Uninitialized(TypeId),
}
impl FunctionKind {
/// Get the underlying `FunctionKind::Import` or panic if this is not an
/// import function
pub fn unwrap_import(&self) -> &ImportedFunction {
match self {
FunctionKind::Import(import) => import,
_ => panic!("not an import function"),
}
}
/// Get the underlying `FunctionKind::Local` or panic if this is not a local
/// function.
pub fn unwrap_local(&self) -> &LocalFunction {
match self {
FunctionKind::Local(l) => l,
_ => panic!("not a local function"),
}
}
/// Get the underlying `FunctionKind::Import` or panic if this is not an
/// import function
pub fn unwrap_import_mut(&mut self) -> &mut ImportedFunction {
match self {
FunctionKind::Import(import) => import,
_ => panic!("not an import function"),
}
}
/// Get the underlying `FunctionKind::Local` or panic if this is not a local
/// function.
pub fn unwrap_local_mut(&mut self) -> &mut LocalFunction {
match self {
FunctionKind::Local(l) => l,
_ => panic!("not a local function"),
}
}
}
/// An externally defined, imported function.
#[derive(Debug)]
pub struct ImportedFunction {
/// The import that brings this function into the module.
pub import: ImportId,
/// The type signature of this imported function.
pub ty: TypeId,
}
/// The set of functions within a module.
#[derive(Debug, Default)]
pub struct ModuleFunctions {
/// The arena containing this module's functions.
arena: TombstoneArena<Function>,
/// Original code section offset.
pub(crate) code_section_offset: usize,
}
impl ModuleFunctions {
/// Construct a new, empty set of functions for a module.
pub fn new() -> ModuleFunctions {
Default::default()
}
/// Create a new externally defined, imported function.
pub fn add_import(&mut self, ty: TypeId, import: ImportId) -> FunctionId {
self.arena.alloc_with_id(|id| Function {
id,
kind: FunctionKind::Import(ImportedFunction { import, ty }),
name: None,
})
}
/// Create a new internally defined function
pub fn add_local(&mut self, func: LocalFunction) -> FunctionId {
let func_name = func.builder().name.clone();
self.arena.alloc_with_id(|id| Function {
id,
kind: FunctionKind::Local(func),
name: func_name,
})
}
/// Gets a reference to a function given its id
pub fn get(&self, id: FunctionId) -> &Function {
&self.arena[id]
}
/// Gets a reference to a function given its id
pub fn get_mut(&mut self, id: FunctionId) -> &mut Function {
&mut self.arena[id]
}
/// Get a function ID by its name.
///
/// The name used is the "name" custom section name and *not* the export
/// name, if a function happens to be exported.
///
/// Note that function names are *not* guaranteed to be unique. This will
/// return the first function in the module with the given name.
pub fn by_name(&self, name: &str) -> Option<FunctionId> {
self.arena.iter().find_map(|(id, f)| {
if f.name.as_ref().map(|s| s.as_str()) == Some(name) {
Some(id)
} else {
None
}
})
}
/// Removes a function from this module.
///
/// It is up to you to ensure that any potential references to the deleted
/// function are also removed, eg `call` expressions, exports, table
/// elements, etc.
pub fn delete(&mut self, id: FunctionId) {
self.arena.delete(id);
}
/// Get a shared reference to this module's functions.
pub fn iter(&self) -> impl Iterator<Item = &Function> {
self.arena.iter().map(|(_, f)| f)
}
/// Get a shared reference to this module's functions.
///
/// Requires the `parallel` feature of this crate to be enabled.
#[cfg(feature = "parallel")]
pub fn par_iter(&self) -> impl ParallelIterator<Item = &Function> {
self.arena.par_iter().map(|(_, f)| f)
}
/// Get an iterator of this module's local functions
pub fn iter_local(&self) -> impl Iterator<Item = (FunctionId, &LocalFunction)> {
self.iter().filter_map(|f| match &f.kind {
FunctionKind::Local(local) => Some((f.id(), local)),
_ => None,
})
}
/// Get a parallel iterator of this module's local functions
///
/// Requires the `parallel` feature of this crate to be enabled.
#[cfg(feature = "parallel")]
pub fn par_iter_local(&self) -> impl ParallelIterator<Item = (FunctionId, &LocalFunction)> {
self.par_iter().filter_map(|f| match &f.kind {
FunctionKind::Local(local) => Some((f.id(), local)),
_ => None,
})
}
/// Get a mutable reference to this module's functions.
pub fn iter_mut(&mut self) -> impl Iterator<Item = &mut Function> {
self.arena.iter_mut().map(|(_, f)| f)
}
/// Get a mutable reference to this module's functions.
///
/// Requires the `parallel` feature of this crate to be enabled.
#[cfg(feature = "parallel")]
pub fn par_iter_mut(&mut self) -> impl ParallelIterator<Item = &mut Function> {
self.arena.par_iter_mut().map(|(_, f)| f)
}
/// Get an iterator of this module's local functions
pub fn iter_local_mut(&mut self) -> impl Iterator<Item = (FunctionId, &mut LocalFunction)> {
self.iter_mut().filter_map(|f| {
let id = f.id();
match &mut f.kind {
FunctionKind::Local(local) => Some((id, local)),
_ => None,
}
})
}
/// Get a parallel iterator of this module's local functions
///
/// Requires the `parallel` feature of this crate to be enabled.
#[cfg(feature = "parallel")]
pub fn par_iter_local_mut(
&mut self,
) -> impl ParallelIterator<Item = (FunctionId, &mut LocalFunction)> {
self.par_iter_mut().filter_map(|f| {
let id = f.id();
match &mut f.kind {
FunctionKind::Local(local) => Some((id, local)),
_ => None,
}
})
}
pub(crate) fn emit_func_section(&self, cx: &mut EmitContext) {
log::debug!("emit function section");
let functions = used_local_functions(cx);
if functions.len() == 0 {
return;
}
let mut func_section = wasm_encoder::FunctionSection::new();
for (id, function, _size) in functions {
let index = cx.indices.get_type_index(function.ty());
func_section.function(index);
// Assign an index to all local defined functions before we start
// translating them. While translating they may refer to future
// functions, so we'll need to have an index for it by that point.
// We're guaranteed the function section is emitted before the code
// section so we should be covered here.
cx.indices.push_func(id);
}
cx.wasm_module.section(&func_section);
}
}
impl Module {
/// Declare local functions after seeing the `function` section of a wasm
/// executable.
pub(crate) fn declare_local_functions(
&mut self,
section: wasmparser::FunctionSectionReader,
ids: &mut IndicesToIds,
) -> Result<()> {
log::debug!("parse function section");
for func in section {
let ty = ids.get_type(func?)?;
let id = self
.funcs
.arena
.alloc_with_id(|id| Function::new_uninitialized(id, ty));
let idx = ids.push_func(id);
if self.config.generate_synthetic_names_for_anonymous_items {
self.funcs.get_mut(id).name = Some(format!("f{}", idx));
}
}
Ok(())
}
/// Add the locally defined functions in the wasm module to this instance.
pub(crate) fn parse_local_functions(
&mut self,
functions: Vec<(FunctionBody<'_>, FuncValidator<ValidatorResources>)>,
indices: &mut IndicesToIds,
on_instr_pos: Option<&(dyn Fn(&usize) -> InstrLocId + Sync + Send + 'static)>,
) -> Result<()> {
log::debug!("parse code section");
let num_imports = self.funcs.arena.len() - functions.len();
// First up serially create corresponding `LocalId` instances for all
// functions as well as extract the operators parser for each function.
// This is pretty tough to parallelize, but we can look into it later if
// necessary and it's a bottleneck!
let mut bodies = Vec::with_capacity(functions.len());
for (i, (body, mut validator)) in functions.into_iter().enumerate() {
let index = (num_imports + i) as u32;
let id = indices.get_func(index)?;
let ty = match self.funcs.arena[id].kind {
FunctionKind::Uninitialized(ty) => ty,
_ => unreachable!(),
};
// First up, implicitly add locals for all function arguments. We also
// record these in the function itself for later processing.
let mut args = Vec::new();
let type_ = self.types.get(ty);
for ty in type_.params().iter() {
let local_id = self.locals.add(*ty);
let idx = indices.push_local(id, local_id);
args.push(local_id);
if self.config.generate_synthetic_names_for_anonymous_items {
let name = format!("arg{}", idx);
self.locals.get_mut(local_id).name = Some(name);
}
}
// Ensure that there exists a `Type` for the function's entry
// block. This is required because multi-value blocks reference a
// `Type`, however function entry's type is implicit in the
// encoding, and doesn't already exist in the `ModuleTypes`.
let results = type_.results().to_vec();
self.types.add_entry_ty(&results);
// Next up comes all the locals of the function.
let mut reader = body.get_binary_reader();
for _ in 0..reader.read_var_u32()? {
let pos = reader.original_position();
let count = reader.read_var_u32()?;
let ty = reader.read_type()?;
validator.define_locals(pos, count, ty)?;
let ty = ValType::parse(&ty)?;
for _ in 0..count {
let local_id = self.locals.add(ty);
let idx = indices.push_local(id, local_id);
if self.config.generate_synthetic_names_for_anonymous_items {
let name = format!("l{}", idx);
self.locals.get_mut(local_id).name = Some(name);
}
}
}
bodies.push((id, reader, args, ty, validator));
}
// Wasm modules can often have a lot of functions and this operation can
// take some time, so parse all function bodies in parallel.
let results = maybe_parallel!(bodies.(into_iter | into_par_iter))
.map(|(id, body, args, ty, validator)| {
(
id,
LocalFunction::parse(
self,
indices,
id,
ty,
args,
body,
on_instr_pos,
validator,
),
)
})
.collect::<Vec<_>>();
// After all the function bodies are collected and finished push them
// into our function arena.
for (id, func) in results {
let func = func?;
self.funcs.arena[id].kind = FunctionKind::Local(func);
}
Ok(())
}
/// Retrieve the ID for the first exported memory.
///
/// This method does not work in contexts with [multi-memory enabled](https://github.com/WebAssembly/multi-memory),
/// and will error if more than one memory is present.
pub fn get_memory_id(&self) -> Result<MemoryId> {
if self.memories.len() > 1 {
bail!("multiple memories unsupported")
}
self.memories
.iter()
.next()
.map(Memory::id)
.context("module does not export a memory")
}
/// Replace a single exported function with the result of the provided builder function.
///
/// The builder function is provided a mutable reference to an [`InstrSeqBuilder`] which can be
/// used to build the function as necessary.
///
/// For example, if you wanted to replace an exported function with a no-op,
///
/// ```ignore
/// module.replace_exported_func(fid, |(body, arg_locals)| {
/// builder.func_body().unreachable();
/// });
/// ```
///
/// The arguments passed to the original function will be passed to the
/// new exported function that was built in your closure.
///
/// This function returns the function ID of the *new* function,
/// after it has been inserted into the module as an export.
pub fn replace_exported_func(
&mut self,
fid: FunctionId,
builder_fn: impl FnOnce((&mut InstrSeqBuilder, &Vec<LocalId>)),
) -> Result<FunctionId> {
let original_export_id = self
.exports
.get_exported_func(fid)
.map(|e| e.id())
.with_context(|| format!("no exported function with ID [{fid:?}]"))?;
if let Function {
kind: FunctionKind::Local(lf),
..
} = self.funcs.get(fid)
{
// Retrieve the params & result types for the exported (local) function
let ty = self.types.get(lf.ty());
let (params, results) = (ty.params().to_vec(), ty.results().to_vec());
// Add the function produced by `fn_builder` as a local function
let mut builder = FunctionBuilder::new(&mut self.types, ¶ms, &results);
let mut new_fn_body = builder.func_body();
builder_fn((&mut new_fn_body, &lf.args));
let func = builder.local_func(lf.args.clone());
let new_fn_id = self.funcs.add_local(func);
// Mutate the existing export to use the new local function
let export = self.exports.get_mut(original_export_id);
export.item = ExportItem::Function(new_fn_id);
Ok(new_fn_id)
} else {
bail!("cannot replace function [{fid:?}], it is not an exported function");
}
}
/// Replace a single imported function with the result of the provided builder function.
///
/// The builder function is provided a mutable reference to an [`InstrSeqBuilder`] which can be
/// used to build the function as necessary.
///
/// For example, if you wanted to replace an imported function with a no-op,
///
/// ```ignore
/// module.replace_imported_func(fid, |(body, arg_locals)| {
/// builder.func_body().unreachable();
/// });
/// ```
///
/// The arguments passed to the original function will be passed to the
/// new exported function that was built in your closure.
///
/// This function returns the function ID of the *new* function, and
/// removes the existing import that has been replaced (the function will become local).
pub fn replace_imported_func(
&mut self,
fid: FunctionId,
builder_fn: impl FnOnce((&mut InstrSeqBuilder, &Vec<LocalId>)),
) -> Result<FunctionId> {
let original_import_id = self
.imports
.get_imported_func(fid)
.map(|import| import.id())
.with_context(|| format!("no exported function with ID [{fid:?}]"))?;
if let Function {
kind: FunctionKind::Import(ImportedFunction { ty: tid, .. }),
..
} = self.funcs.get(fid)
{
// Retrieve the params & result types for the imported function
let ty = self.types.get(*tid);
let (params, results) = (ty.params().to_vec(), ty.results().to_vec());
// Build the list LocalIds used by args to match the original function
let args = params
.iter()
.map(|ty| self.locals.add(*ty))
.collect::<Vec<_>>();
// Build the new function
let mut builder = FunctionBuilder::new(&mut self.types, ¶ms, &results);
let mut new_fn_body = builder.func_body();
builder_fn((&mut new_fn_body, &args));
let new_func_kind = FunctionKind::Local(builder.local_func(args));
// Mutate the existing function, changing it from a FunctionKind::ImportedFunction
// to the local function produced by running the provided `fn_builder`
let func = self.funcs.get_mut(fid);
func.kind = new_func_kind;
self.imports.delete(original_import_id);
Ok(fid)
} else {
bail!("cannot replace function [{fid:?}], it is not an imported function");
}
}
}
fn used_local_functions<'a>(cx: &mut EmitContext<'a>) -> Vec<(FunctionId, &'a LocalFunction, u64)> {
// Extract all local functions because imported ones were already
// emitted as part of the import sectin. Find the size of each local
// function. Sort imported functions in order so that we can get their
// index in the function index space.
let mut functions = Vec::new();
for f in cx.module.funcs.iter() {
match &f.kind {
FunctionKind::Local(l) => functions.push((f.id(), l, l.size())),
FunctionKind::Import(_) => {}
FunctionKind::Uninitialized(_) => unreachable!(),
}
}
// Sort local functions from largest to smallest; we will emit them in
// this order. This helps load times, since wasm engines generally use
// the function as their level of granularity for parallelism. We want
// larger functions compiled before smaller ones because they will take
// longer to compile.
functions.sort_by_key(|(id, _, size)| (cmp::Reverse(*size), *id));
functions
}
fn collect_non_default_code_offsets(
code_transform: &mut BTreeMap<InstrLocId, usize>,
code_offset: usize,
map: Vec<(InstrLocId, usize)>,
) {
for (src, dst) in map {
let dst = dst + code_offset;
if !src.is_default() {
code_transform.insert(src, dst);
}
}
}
impl Emit for ModuleFunctions {
fn emit(&self, cx: &mut EmitContext) {
log::debug!("emit code section");
let functions = used_local_functions(cx);
if functions.len() == 0 {
return;
}
let mut wasm_code_section = wasm_encoder::CodeSection::new();
let generate_map = cx.module.config.preserve_code_transform;
// Functions can typically take awhile to serialize, so serialize
// everything in parallel. Afterwards we'll actually place all the
// functions together.
let bytes = maybe_parallel!(functions.(into_iter | into_par_iter))
.map(|(id, func, _size)| {
log::debug!("emit function {:?} {:?}", id, cx.module.funcs.get(id).name);
let mut wasm = Vec::new();
let mut map = if generate_map { Some(Vec::new()) } else { None };
let (locals_types, used_locals, local_indices) = func.emit_locals(cx.module);
let mut wasm_function = wasm_encoder::Function::new(locals_types);
func.emit_instructions(
cx.indices,
&local_indices,
&mut wasm_function,
map.as_mut(),
);
wasm_function.encode(&mut wasm);
(
wasm,
wasm_function.byte_len(),
id,
used_locals,
local_indices,
map,
)
})
.collect::<Vec<_>>();
let mut instruction_map = BTreeMap::new();
cx.indices.locals.reserve(bytes.len());
let mut offset_data = Vec::new();
for (wasm, byte_len, id, used_locals, local_indices, map) in bytes {
let leb_len = wasm.len() - byte_len;
wasm_code_section.raw(&wasm[leb_len..]);
cx.indices.locals.insert(id, local_indices);
cx.locals.insert(id, used_locals);
offset_data.push((byte_len, id, map, leb_len));
}
cx.wasm_module.section(&wasm_code_section);
let code_section_start_offset =
cx.wasm_module.as_slice().len() - wasm_code_section.byte_len();
let mut cur_offset = code_section_start_offset;
// update the map afterwards based on final offset differences
for (byte_len, id, map, leb_len) in offset_data {
// (this assumes the leb encodes the same)
let code_start_offset = cur_offset + leb_len;
cur_offset += leb_len + byte_len;
if let Some(map) = map {
collect_non_default_code_offsets(&mut instruction_map, code_start_offset, map);
}
cx.code_transform.function_ranges.push((
id,
Range {
// inclusive leb part
start: code_start_offset - leb_len,
end: cur_offset,
},
));
}
cx.code_transform.function_ranges.sort_by_key(|i| i.0);
// FIXME: code section start in DWARF debug information expects 2 bytes before actual code section start.
cx.code_transform.code_section_start = code_section_start_offset - 2;
cx.code_transform.instruction_map = instruction_map.into_iter().collect();
}
}
#[cfg(test)]
mod tests {
use super::*;
use crate::{Export, FunctionBuilder, Module};
#[test]
fn get_memory_id() {
let mut module = Module::default();
let expected_id = module.memories.add_local(false, 0, None);
assert!(module.get_memory_id().is_ok_and(|id| id == expected_id));
}
/// Running `replace_exported_func` with a closure that builds
/// a function should replace the existing function with the new one
#[test]
fn replace_exported_func() {
let mut module = Module::default();
// Create original function
let mut builder = FunctionBuilder::new(&mut module.types, &[], &[]);
builder.func_body().i32_const(1234).drop();
let original_fn_id: FunctionId = builder.finish(vec![], &mut module.funcs);
let original_export_id = module.exports.add("dummy", original_fn_id);
// Replace the existing function with a new one with a reversed const value
let new_fn_id = module
.replace_exported_func(original_fn_id, |(body, _)| {
body.i32_const(4321).drop();
})
.expect("function replacement worked");
assert!(
module.exports.get_exported_func(original_fn_id).is_none(),
"replaced function cannot be gotten by ID"
);
// Ensure the function was replaced
match module
.exports
.get_exported_func(new_fn_id)
.expect("failed to unwrap exported func")
{
exp @ Export {
item: ExportItem::Function(fid),
..
} => {
assert_eq!(*fid, new_fn_id, "retrieved function ID matches");
assert_eq!(exp.id(), original_export_id, "export ID is unchanged");
}
_ => panic!("expected an Export with a Function inside"),
}
}
/// Running `replace_exported_func` with a closure that returns None
/// should replace the function with a generated no-op function
#[test]
fn replace_exported_func_generated_no_op() {
let mut module = Module::default();
// Create original function
let mut builder = FunctionBuilder::new(&mut module.types, &[], &[]);
builder.func_body().i32_const(1234).drop();
let original_fn_id: FunctionId = builder.finish(vec![], &mut module.funcs);
let original_export_id = module.exports.add("dummy", original_fn_id);
// Replace the existing function with a new one with a reversed const value
let new_fn_id = module
.replace_exported_func(original_fn_id, |(body, _arg_locals)| {
body.unreachable();
})
.expect("export function replacement worked");
assert!(
module.exports.get_exported_func(original_fn_id).is_none(),
"replaced export function cannot be gotten by ID"
);
// Ensure the function was replaced
match module
.exports
.get_exported_func(new_fn_id)
.expect("failed to unwrap exported func")
{
exp @ Export {
item: ExportItem::Function(fid),
name,
..
} => {
assert_eq!(name, "dummy", "function name on export is unchanged");
assert_eq!(*fid, new_fn_id, "retrieved function ID matches");
assert_eq!(exp.id(), original_export_id, "export ID is unchanged");
}
_ => panic!("expected an Export with a Function inside"),
}
}
/// Running `replace_imported_func` with a closure that builds
/// a function should replace the existing function with the new one
#[test]
fn replace_imported_func() {
let mut module = Module::default();
// Create original import function
let types = module.types.add(&[], &[]);
let (original_fn_id, original_import_id) = module.add_import_func("mod", "dummy", types);
// Replace the existing function with a new one with a reversed const value
let new_fn_id = module
.replace_imported_func(original_fn_id, |(body, _)| {
body.i32_const(4321).drop();
})
.expect("import fn replacement worked");
assert!(
!module.imports.iter().any(|i| i.id() == original_import_id),
"original import is missing",
);
assert!(
module.imports.get_imported_func(original_fn_id).is_none(),
"replaced import function cannot be gotten by ID"
);
assert!(
module.imports.get_imported_func(new_fn_id).is_none(),
"new import function cannot be gotten by ID (it is now local)"
);
assert!(
matches!(module.funcs.get(new_fn_id).kind, FunctionKind::Local(_)),
"new local function has the right kind"
);
}
/// Running `replace_imported_func` with a closure that returns None
/// should replace the function with a generated no-op function
#[test]
fn replace_imported_func_generated_no_op() {
let mut module = Module::default();
// Create original import function
let types = module.types.add(&[], &[]);
let (original_fn_id, original_import_id) = module.add_import_func("mod", "dummy", types);
// Replace the existing function with a new one with a reversed const value
let new_fn_id = module
.replace_imported_func(original_fn_id, |(body, _arg_locals)| {
body.unreachable();
})
.expect("import fn replacement worked");
assert!(
!module.imports.iter().any(|i| i.id() == original_import_id),
"original import is missing",
);
assert!(
module.imports.get_imported_func(original_fn_id).is_none(),
"replaced import function cannot be gotten by ID"
);
assert!(
module.imports.get_imported_func(new_fn_id).is_none(),
"new import function cannot be gotten by ID (it is now local)"
);
assert!(
matches!(module.funcs.get(new_fn_id).kind, FunctionKind::Local(_)),
"new local function has the right kind"
);
}
}