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ydnarydnar
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Merge pull request #353 from bytecodealliance/ydnar/issue350
wit: align record size to max field alignment
2 parents 6bcf449 + cf9588b commit 5c4ace4

16 files changed

Lines changed: 64 additions & 19 deletions

‎CHANGELOG.md‎

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@@ -11,6 +11,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
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### Fixed
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- [#306](https://github.com/bytecodealliance/go-modules/issues/306): do not emit incompatible version feature gates when serializing WIT. For example, if a world with version `0.1.0` *includes* a world from another package with a `@since(version = 0.2.0)` feature gate, then strip that feature gate when serializing to WIT if the version is greater than the world’s package version.
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- [#350](https://github.com/bytecodealliance/go-modules/issues/350): correctly align `record` size to the highest alignment of its fields, per [specification](https://github.com/WebAssembly/component-model/blob/main/design/mvp/CanonicalABI.md#element-size).
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## [v0.6.2] — 2025-03-16

‎cm/result_test.go‎

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@@ -387,3 +387,37 @@ func TestIssue344BoolResult(t *testing.T) {
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t.Errorf("*v.OK(): %v, expected %v", got, want)
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}
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}
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func TestIssue350(t *testing.T) {
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type Shape struct {
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_ HostLayout
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shape [unsafe.Sizeof(Tuple3[uint16, Result[uint64, uint64, struct{}], uint8]{})]byte
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// Previously, with bug in (*Record).Size() algorithm:
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// shape [unsafe.Sizeof(Option[[3]string]{})]byte
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}
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type O Option[[3]string]
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type E Tuple3[uint16, Result[uint64, uint64, struct{}], uint8]
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type T Result[Shape, O, E]
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shapeSize := unsafe.Sizeof(Shape{})
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errSize := unsafe.Sizeof(E{})
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if errSize > shapeSize {
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t.Errorf("size of err type (%d) > size of shape type (%d)", errSize, shapeSize)
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var e E
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base := uintptr(unsafe.Pointer(&e))
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f0 := uintptr(unsafe.Pointer(&e.F0)) - base
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f1 := uintptr(unsafe.Pointer(&e.F1)) - base
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f2 := uintptr(unsafe.Pointer(&e.F2)) - base
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t.Logf("Offsets: F0: %d F1: %d F2 %d", f0, f1, f2)
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}
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// _ = Err[T](
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// Err, uint8]{
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// F0: 0,
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// F1: OK[Result[uint64, uint64, struct{}]](0),
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// F2: 0,
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// },
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// )
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}

‎wit/abi.go‎

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@@ -9,7 +9,7 @@ import (
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// [Canonical ABI] [size], [alignment], and [flat] representation.
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//
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// [Canonical ABI]: https://github.com/WebAssembly/component-model/blob/main/design/mvp/CanonicalABI.md
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// [size]: https://github.com/WebAssembly/component-model/blob/main/design/mvp/CanonicalABI.md#size
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// [size]: https://github.com/WebAssembly/component-model/blob/main/design/mvp/CanonicalABI.md#element-size
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// [alignment]: https://github.com/WebAssembly/component-model/blob/main/design/mvp/CanonicalABI.md#alignment
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// [flat]: https://github.com/WebAssembly/component-model/blob/main/design/mvp/CanonicalABI.md#flattening
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type ABI interface {

‎wit/abi_test.go‎

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@@ -99,7 +99,7 @@ func TestDiscriminant(t *testing.T) {
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}
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}
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func TestTypeSize(t *testing.T) {
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func TestTypeSizeAndAlign(t *testing.T) {
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tests := []struct {
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name string
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v Type
@@ -119,6 +119,10 @@ func TestTypeSize(t *testing.T) {
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{"f64", F64{}, 8, 8},
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{"char", Char{}, 4, 4},
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{"string", String{}, 8, 4},
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{"option<string>", &TypeDef{Kind: &Option{Type: String{}}}, 12, 4},
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{"option<f32>", &TypeDef{Kind: &Option{Type: F32{}}}, 8, 4},
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{"variant", &TypeDef{Kind: &Variant{Cases: []Case{{Type: String{}}, {Type: F64{}}}}}, 16, 8},
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{"record", &TypeDef{Kind: &Record{Fields: []Field{{Type: U16{}}, {Type: &TypeDef{Kind: &Result{OK: U64{}}}}, {Type: U8{}}}}}, 32, 8},
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}
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for _, tt := range tests {
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t.Run(tt.name, func(t *testing.T) {
@@ -156,6 +160,7 @@ func TestTypeFlat(t *testing.T) {
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{"option<string>", &TypeDef{Kind: &Option{Type: String{}}}, []Type{U32{}, PointerTo(U8{}), U32{}}},
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{"option<f32>", &TypeDef{Kind: &Option{Type: F32{}}}, []Type{U32{}, F32{}}},
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{"variant", &TypeDef{Kind: &Variant{Cases: []Case{{Type: String{}}, {Type: F64{}}}}}, []Type{U32{}, U64{}, U32{}}},
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{"record", &TypeDef{Kind: &Record{Fields: []Field{{Type: U16{}}, {Type: &TypeDef{Kind: &Result{OK: U64{}}}}, {Type: U8{}}}}}, []Type{U32{}, U32{}, U64{}, U32{}}},
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}
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for _, tt := range tests {
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t.Run(tt.name, func(t *testing.T) {
@@ -177,9 +182,6 @@ func witFor[T Node](nodes ...T) []string {
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// TestHasBorrow verifies that HasBorrow returns true for WIT types that contain a Borrow type.
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func TestHasBorrow(t *testing.T) {
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makeBorrow := func() *TypeDef { return &TypeDef{Kind: &Borrow{}} }
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makeTypeDef := func(kind TypeDefKind) *TypeDef { return &TypeDef{Kind: kind} }
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testCases := []struct {
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name string
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typeDef *TypeDef
@@ -211,3 +213,11 @@ func TestHasBorrow(t *testing.T) {
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})
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}
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}
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func makeTypeDef(kind TypeDefKind) *TypeDef {
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return &TypeDef{Kind: kind}
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}
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func makeBorrow() *TypeDef {
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return &TypeDef{Kind: &Borrow{}}
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}

‎wit/enum.go‎

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@@ -29,7 +29,7 @@ func (e *Enum) Despecialize() TypeDefKind {
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// type that can represent 0...len(e.Cases).
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// It is first [despecialized] into a [Variant] with no associated types, then sized.
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//
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// [ABI byte size]: https://github.com/WebAssembly/component-model/blob/main/design/mvp/CanonicalABI.md#size
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// [ABI byte size]: https://github.com/WebAssembly/component-model/blob/main/design/mvp/CanonicalABI.md#element-size
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// [despecialized]: https://github.com/WebAssembly/component-model/blob/main/design/mvp/CanonicalABI.md#despecialization
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func (e *Enum) Size() uintptr {
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return e.Despecialize().Size()

‎wit/flags.go‎

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@@ -11,7 +11,7 @@ type Flags struct {
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// Size returns the [ABI byte size] of [Flags] f.
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//
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// [ABI byte size]: https://github.com/WebAssembly/component-model/blob/main/design/mvp/CanonicalABI.md#size
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// [ABI byte size]: https://github.com/WebAssembly/component-model/blob/main/design/mvp/CanonicalABI.md#element-size
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func (f *Flags) Size() uintptr {
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n := len(f.Flags)
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switch {

‎wit/future.go‎

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@@ -12,7 +12,7 @@ type Future struct {
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// Size returns the [ABI byte size] for a [Future].
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//
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// [ABI byte size]: https://github.com/WebAssembly/component-model/blob/main/design/mvp/CanonicalABI.md#size
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// [ABI byte size]: https://github.com/WebAssembly/component-model/blob/main/design/mvp/CanonicalABI.md#element-size
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func (*Future) Size() uintptr { return 4 }
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// Align returns the [ABI byte alignment] a [Future].

‎wit/list.go‎

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@@ -11,7 +11,7 @@ type List struct {
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// Size returns the [ABI byte size] for a [List].
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//
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// [ABI byte size]: https://github.com/WebAssembly/component-model/blob/main/design/mvp/CanonicalABI.md#size
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// [ABI byte size]: https://github.com/WebAssembly/component-model/blob/main/design/mvp/CanonicalABI.md#element-size
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func (*List) Size() uintptr { return 8 } // [2]int32
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// Align returns the [ABI byte alignment] a [List].

‎wit/option.go‎

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@@ -27,7 +27,7 @@ func (o *Option) Despecialize() TypeDefKind {
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// Size returns the [ABI byte size] for [Option] o.
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// It is first [despecialized] into a [Variant] with two cases, "none" and "some(T)", then sized.
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//
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// [ABI byte size]: https://github.com/WebAssembly/component-model/blob/main/design/mvp/CanonicalABI.md#size
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// [ABI byte size]: https://github.com/WebAssembly/component-model/blob/main/design/mvp/CanonicalABI.md#element-size
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// [despecialized]: https://github.com/WebAssembly/component-model/blob/main/design/mvp/CanonicalABI.md#despecialization
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func (o *Option) Size() uintptr {
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return o.Despecialize().Size()

‎wit/pointer.go‎

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@@ -14,7 +14,7 @@ type Pointer struct {
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// Size returns the [ABI byte size] for [Pointer].
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//
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// [ABI byte size]: https://github.com/WebAssembly/component-model/blob/main/design/mvp/CanonicalABI.md#size
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// [ABI byte size]: https://github.com/WebAssembly/component-model/blob/main/design/mvp/CanonicalABI.md#element-size
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func (*Pointer) Size() uintptr { return 4 }
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// Align returns the [ABI byte alignment] for [Pointer].

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