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https://github.com/fluencelabs/wasm-bindgen
synced 2025-03-17 10:40:50 +00:00
Get rid of the wasm interface types return pointer hacks
Now that using standard Wasm interface types implies multi-value support, we don't need these return pointer hacks anymore.
This commit is contained in:
Nick Fitzgerald
parent
311ae1941f
commit
25dd84c503
@ -954,7 +954,10 @@ impl<'a> Context<'a> {
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match op.kind {
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decode::OperationKind::Regular => {
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if op.is_static {
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Ok((AuxImport::ValueWithThis(class, function.name.to_string()), false))
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Ok((
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AuxImport::ValueWithThis(class, function.name.to_string()),
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false,
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))
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} else if structural {
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Ok((
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AuxImport::StructuralMethod(function.name.to_string()),
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@ -1361,48 +1364,26 @@ impl<'a> Context<'a> {
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.bindings
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.get(bind.binding)
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.ok_or_else(|| format_err!("bad binding id"))?;
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let mut return_via_outptr = None;
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let (wasm_ty, webidl_ty, incoming, outgoing) = match binding {
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ast::FunctionBinding::Export(e) => {
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// This `match` is weird, see the comment at the top of
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// `standard.rs` for what it's doing.
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let outgoing = match e.result.bindings.get(0) {
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Some(ast::OutgoingBindingExpression::As(a)) if a.idx == u32::max_value() => {
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return_via_outptr = Some(vec![walrus::ValType::I32, walrus::ValType::I32]);
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&e.result.bindings[1..]
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}
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_ => &e.result.bindings[..],
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};
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(
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e.wasm_ty,
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e.webidl_ty,
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e.params.bindings.as_slice(),
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outgoing,
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)
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}
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ast::FunctionBinding::Import(e) => {
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// This `match` is weird, see the comment at the top of
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// `standard.rs` for what it's doing.
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let incoming = match e.result.bindings.get(0) {
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Some(ast::IncomingBindingExpression::Get(g)) if g.idx == u32::max_value() => {
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return_via_outptr = Some(vec![walrus::ValType::I32, walrus::ValType::I32]);
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&e.result.bindings[1..]
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}
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_ => &e.result.bindings[..],
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};
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(
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e.wasm_ty,
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e.webidl_ty,
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incoming,
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e.params.bindings.as_slice(),
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)
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}
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ast::FunctionBinding::Export(e) => (
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e.wasm_ty,
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e.webidl_ty,
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e.params.bindings.as_slice(),
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&e.result.bindings[..],
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),
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ast::FunctionBinding::Import(e) => (
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e.wasm_ty,
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e.webidl_ty,
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&e.result.bindings[..],
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e.params.bindings.as_slice(),
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),
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};
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let webidl_ty = standard::copy_ty(&mut self.bindings.types, webidl_ty, &std.types);
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let webidl_ty = match webidl_ty {
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ast::WebidlTypeRef::Id(id) => <ast::WebidlFunction as ast::WebidlTypeId>::wrap(id),
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_ => bail!("invalid webidl type listed"),
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};
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Ok(Binding {
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wasm_ty,
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webidl_ty,
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@ -1416,7 +1397,7 @@ impl<'a> Context<'a> {
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.cloned()
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.map(NonstandardOutgoing::Standard)
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.collect(),
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return_via_outptr,
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return_via_outptr: None,
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})
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}
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@ -16,39 +16,6 @@
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//! generating any JS glue. Any JS glue currently generated is also invalid if
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//! the module contains the wasm bindings section and it's actually respected.
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// NB: Returning strings is weird
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//
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// This module has what is currently a pretty gross hack for dealing with
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// returning strings. One of the banner features of WebIDL bindings is not
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// requiring any language-specific glue to use wasm files and you get all sorts
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// of types like integers and strings by default. Note that strings are a huge
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// thing here.
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//
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// Dealing with *incoming* strings is easy enough in that the binding expression
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// has an allocator function to call and it's filled in and passed as two
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// pointers. Outgoing strings are a little harder, however, for two reasons:
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//
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// * One is that we need to return two values, which requires multi-value
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// * Another is that someone's got to free the string at some point
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//
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// Rust/wasm-bindgen don't support multi-value, and WebIDL bindings as literally
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// spec'd right this red hot second don't support freeing strings that we pass
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// out. These both have obvious fixes (supporting multi-value and extending the
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// bindings spec to support freeing) but we also want something working right
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// this red-hot second.
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//
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// To get things working we employ a terrible hack where the first bindign
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// expression of the result a function may indicate "use a thing that's way off
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// in the ether" and that's actually a sentinel for "oh ignore everything else
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// and the string is returned through an out-ptr as the first argument". This
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// manifests in all sorts of special hacks all over the place to handle this,
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// and it's a real bummer.
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//
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// This is in general just an explainer for the current state of things and
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// also a preemptive apology for writing the code to handle this in so many
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// places. I, like you, look forward to actually fixing this for real as the
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// spec continues to evolve and we implement more in wasm-bindgen.
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use crate::descriptor::VectorKind;
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use crate::webidl::{AuxExportKind, AuxImport, AuxValue, JsImport, JsImportName};
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use crate::webidl::{NonstandardIncoming, NonstandardOutgoing};
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@ -240,7 +207,7 @@ pub fn add_section(
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name
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)
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})?;
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let mut result = extract_outgoing(&binding.outgoing).with_context(|_| {
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let result = extract_outgoing(&binding.outgoing).with_context(|_| {
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format!(
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"failed to map return value for export `{}` to standard \
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binding expressions",
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@ -248,18 +215,7 @@ pub fn add_section(
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)
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})?;
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// see comment at top of this module about returning strings for what
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// this is doing and why it's weird
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if binding.return_via_outptr.is_some() {
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result.insert(
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0,
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ast::OutgoingBindingExpressionAs {
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idx: u32::max_value(),
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ty: ast::WebidlScalarType::Long.into(),
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}
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.into(),
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);
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}
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assert!(binding.return_via_outptr.is_none());
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let binding = section.bindings.insert(ast::ExportBinding {
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wasm_ty: binding.wasm_ty,
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webidl_ty: copy_ty(
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@ -293,24 +249,14 @@ pub fn add_section(
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module_name, name,
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)
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})?;
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let mut result = extract_incoming(&binding.incoming).with_context(|_| {
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let result = extract_incoming(&binding.incoming).with_context(|_| {
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format!(
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"failed to map return value of import `{}::{}` to standard \
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binding expressions",
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module_name, name,
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)
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})?;
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// see comment at top of this module about returning strings for what
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// this is doing and why it's weird
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if binding.return_via_outptr.is_some() {
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result.insert(
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0,
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ast::IncomingBindingExpressionGet {
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idx: u32::max_value(),
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}
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.into(),
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);
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}
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assert!(binding.return_via_outptr.is_none());
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let binding = section.bindings.insert(ast::ImportBinding {
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wasm_ty: binding.wasm_ty,
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webidl_ty: copy_ty(
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