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Add annotations proposal implementation #322

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abf4c6c
Add annotations proposal implementation
MaxDesiatov Mar 16, 2026
1b0da45
Fix dependencies.json duplicates
MaxDesiatov Mar 16, 2026
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5 changes: 1 addition & 4 deletions Package.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -88,10 +88,7 @@ let package = Package(
.testTarget(
name: "WATTests",
dependencies: [
.target(
name: "WasmTools",
condition: .when(traits: ["ComponentModel"])
),
"WasmTools",
"WAT",
]
),
Expand Down
2 changes: 1 addition & 1 deletion README.md
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Expand Up @@ -101,7 +101,7 @@ Proposals are grouped by their [phase](https://github.com/WebAssembly/meetings/b
| [Tail Call](https://github.com/WebAssembly/tail-call) | ✅ Implemented | [0.1.4] |
| [Typed Function References](https://github.com/WebAssembly/function-references) | 🚧 Parser implemented | [0.2.0] |
| [Branch Hinting](https://github.com/WebAssembly/branch-hinting) | ❌ Not implemented | |
| [Custom Annotation Syntax in the Text Format](https://github.com/WebAssembly/annotations) | ❌ Not implemented | |
| [Custom Annotation Syntax in the Text Format](https://github.com/WebAssembly/annotations) | ✅ Implemented | `main` branch |
| [Exception Handling](https://github.com/WebAssembly/exception-handling) | ❌ Not implemented | |
| [Extended Constant Expressions](https://github.com/WebAssembly/extended-const) | ❌ Not implemented | |
| [Garbage Collection](https://github.com/WebAssembly/gc) | ❌ Not implemented | |
Expand Down
72 changes: 64 additions & 8 deletions Sources/WAT/BinaryEncoding/Encoder.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -29,7 +29,17 @@ package struct Encoder {
output.append(contentsOf: contentEncoder.output)
}

package mutating func encodeVector<Source: Collection, E: Error>(
/// Overload accepting any RawRepresentable<UInt8> for ergonomic use with enums.
mutating func section<ID: RawRepresentable<UInt8>, E: Error>(id: ID, _ sectionContent: (inout Encoder) throws(E) -> Void) throws(E) {
try section(id: id.rawValue, sectionContent)
}

/// Append a single byte from any RawRepresentable<UInt8> value.
mutating func append<T: RawRepresentable<UInt8>>(_ value: T) {
output.append(value.rawValue)
}

mutating func encodeVector<Source: Collection, E: Error>(
_ values: Source, encodeElement: (Source.Element, inout Encoder) throws(E) -> Void
) throws(E) {
writeUnsignedLEB128(UInt32(values.count))
Expand Down Expand Up @@ -311,7 +321,7 @@ extension WAT.WatParser.ElementDecl {
case .refNull(let type):
try exprEncoder.visitRefNull(type: type)
default:
throw WatParserError("unexpected instruction in element expression (\(instruction)", location: nil)
throw WatParserError("unexpected instruction in element expression \(instruction)", location: nil)
}
try exprEncoder.visitEnd()
encoder.output.append(contentsOf: exprEncoder.encoder.output)
Expand Down Expand Up @@ -582,22 +592,28 @@ func encode(module: inout Wat, options: EncodeOptions) throws(WatParserError) ->
encoder.writeHeader()

var codeEncoder = Encoder()
let functions = module.functionsMap.compactMap { (function: WatParser.FunctionDecl) -> ([WatParser.LocalDecl], WatParser.FunctionDecl)? in
let functions = module.functionsMap.enumerated().compactMap { (index: Int, function: WatParser.FunctionDecl) -> (Int, [WatParser.LocalDecl], WatParser.FunctionDecl)? in
guard case .definition(let locals, _) = function.kind else {
return nil
}
return (locals, function)
return (index, locals, function)
}
var functionSection: [UInt32] = []
var hasDataSegmentInstruction = false
var functionLabelNames: [[(Int, String)]] = []

// Track function type indices for name section (maps function definition index to type index)
var functionTypeIndices: [Int: Int] = [:]
// Track label names per function for name section subsection 3
var labelNamesPerFunction: [(funcIndex: Int, labels: [(index: Int, name: String)])] = []
var definitionIndex = 0

if !functions.isEmpty {
try codeEncoder.section(id: 0x0A) { encoder throws(WatParserError) in
try encoder.encodeVector(
functions,
encodeElement: { source, encoder throws(WatParserError) in
let (locals, function) = source
let (funcIndex, locals, function) = source
var exprEncoder = ExpressionEncoder()
// Encode locals
var localsEntries: [(type: ValueType, count: UInt32)] = []
Expand Down Expand Up @@ -625,30 +641,48 @@ func encode(module: inout Wat, options: EncodeOptions) throws(WatParserError) ->
}
}

let cs = module.customSections

func emitCustomSections(placement: CustomSectionDecl.Placement, encoder: inout Encoder) {
for section in cs where section.placement == placement {
encoder.section(id: 0) { encoder in
section.name.encode(to: &encoder)
encoder.output.append(contentsOf: section.content)
}
}
}

// Section 1: Type section
emitCustomSections(placement: .before(.type), encoder: &encoder)
if !module.types.isEmpty {
encoder.section(id: 0x01) { encoder in
encoder.encodeVector(module.types, transform: \.type.signature)
}
}
emitCustomSections(placement: .after(.type), encoder: &encoder)

// Section 2: Import section
emitCustomSections(placement: .before(.import), encoder: &encoder)
if !module.imports.isEmpty {
encoder.section(id: 0x02) { encoder in
encoder.encodeVector(module.imports)
}
}
emitCustomSections(placement: .after(.import), encoder: &encoder)

// Section 3: Function section
emitCustomSections(placement: .before(.func), encoder: &encoder)
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@kateinoigakukun kateinoigakukun Mar 29, 2026

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It's very error-prune to enforce inserting emitCustomSections before/after each section manually. Can we make it as a part of Encoder.section?

if !functionSection.isEmpty {
encoder.section(id: 0x03) { encoder in
encoder.encodeVector(functionSection) { typeIndex, encoder in
encoder.writeUnsignedLEB128(UInt32(typeIndex))
}
}
}
emitCustomSections(placement: .after(.func), encoder: &encoder)

// Section 4: Table section
emitCustomSections(placement: .before(.table), encoder: &encoder)
let tables = module.tablesMap.definitions()
if !tables.isEmpty {
try encoder.section(id: 0x04) { encoder throws(WatParserError) in
Expand All @@ -657,16 +691,20 @@ func encode(module: inout Wat, options: EncodeOptions) throws(WatParserError) ->
}
}
}
emitCustomSections(placement: .after(.table), encoder: &encoder)

// Section 5: Memory section
emitCustomSections(placement: .before(.memory), encoder: &encoder)
let memories = module.memories.definitions()
if !memories.isEmpty {
encoder.section(id: 0x05) { encoder in
encoder.encodeVector(memories)
}
}
emitCustomSections(placement: .after(.memory), encoder: &encoder)

// Section 6: Global section
emitCustomSections(placement: .before(.global), encoder: &encoder)
let globals = module.globals.definitions()
if !globals.isEmpty {
try encoder.section(id: 0x06) { encoder throws(WatParserError) in
Expand All @@ -675,31 +713,38 @@ func encode(module: inout Wat, options: EncodeOptions) throws(WatParserError) ->
}
}
}
emitCustomSections(placement: .after(.global), encoder: &encoder)

// Section 7: Export section
emitCustomSections(placement: .before(.export), encoder: &encoder)
if !module.exports.isEmpty {
encoder.section(id: 0x07) { encoder in
encoder.encodeVector(module.exports) { export, encoder in
export.encode(to: &encoder)
}
}
}
emitCustomSections(placement: .after(.export), encoder: &encoder)

// Section 8: Start section
emitCustomSections(placement: .before(.start), encoder: &encoder)
if let start = module.start {
encoder.section(id: 0x08) { encoder in
encoder.writeUnsignedLEB128(start)
}
}
emitCustomSections(placement: .after(.start), encoder: &encoder)

// Section 9: Element section
emitCustomSections(placement: .before(.elem), encoder: &encoder)
if !module.elementsMap.isEmpty {
try encoder.section(id: 0x09) { encoder throws(WatParserError) in
try encoder.encodeVector(module.elementsMap) { element, encoder throws(WatParserError) in
try element.encode(to: &encoder, wat: &module)
}
}
}
emitCustomSections(placement: .after(.elem), encoder: &encoder)

// Section 12: DataCount section
if !module.data.isEmpty, hasDataSegmentInstruction {
Expand All @@ -709,22 +754,33 @@ func encode(module: inout Wat, options: EncodeOptions) throws(WatParserError) ->
}

// Section 10: Code section
emitCustomSections(placement: .before(.code), encoder: &encoder)
encoder.output.append(contentsOf: codeEncoder.output)
emitCustomSections(placement: .after(.code), encoder: &encoder)

// Section 11: Data section
emitCustomSections(placement: .before(.data), encoder: &encoder)
if !module.data.isEmpty {
try encoder.section(id: 0x0B) { encoder throws(WatParserError) in
try encoder.encodeVector(module.data) { data, encoder throws(WatParserError) in
try data.encode(to: &encoder, wat: &module)
}
}
}
emitCustomSections(placement: .after(.data), encoder: &encoder)

// Unplaced custom sections go after all standard sections
emitCustomSections(placement: .unplaced, encoder: &encoder)

// (Optional) Name Section
if options.nameSection {
try encodeNameSection(module: &module, options: options, encoder: &encoder, functions: functions, functionLabelNames: functionLabelNames)
try encodeNameSection(module: &module, options: options, encoder: &encoder, functions: functions.map { ($0.1, $0.2) }, functionLabelNames: functionLabelNames)
}

// "last" placement goes after everything including the name section
emitCustomSections(placement: .before(.last), encoder: &encoder)
emitCustomSections(placement: .after(.last), encoder: &encoder)

return encoder.output
}

Expand Down Expand Up @@ -851,9 +907,9 @@ private func encodeNameSection(
encoder.section(id: 0) { encoder in
encoder.encode("name")

if let moduleId = module.id {
if let moduleName = module.id {
encoder.section(id: 0) { encoder in
encoder.encode(String(moduleId.dropFirst())) // Drop "$" prefix
encoder.encode(moduleName.nameValue)
}
}
if !functionNames.isEmpty {
Expand Down
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