cm, wit/bindgen: add HostLayout field to generated structs

CHANGELOG.md

@@ -6,8 +6,9 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 
 ### Added
 
+- Generated structs and structs in package `cm` now include a [`HostLayout` field](https://github.com/golang/go/issues/66408) in order to conform with the [relaxed types proposal](https://github.com/golang/go/issues/66984) for `GOARCH=wasm32`. The `cm.HostLayout` type is an alias for `structs.HostLayout` on Go 1.23 or later, and a polyfill for Go 1.22 or earlier.
 - [#163](https://github.com/bytecodealliance/wasm-tools-go/issues/163): added `cm.F32ToU64()` and `cm.U64ToF32()` for flattening `f32` and `u64` types in the Canonical ABI.
-- Test data from [bytecodealliance/wit-bindgen/tests/codegen](https://github.com/bytecodealliance/wit-bindgen/tree/main/tests/codegen)
+- Test data from [bytecodealliance/wit-bindgen/tests/codegen](https://github.com/bytecodealliance/wit-bindgen/tree/main/tests/codegen).
 
 ### Fixed
 

cm/hostlayout_go122.go

@@ -0,0 +1,11 @@
+//go:build !go1.23
+
+package cm
+
+// HostLayout marks a struct as using host memory layout.
+// See [structs.HostLayout] in Go 1.23 or later.
+type HostLayout struct {
+	_ hostLayout // prevent accidental conversion with plain struct{}
+}
+
+type hostLayout struct{}

cm/hostlayout_go123.go

@@ -0,0 +1,9 @@
+//go:build go1.23
+
+package cm
+
+import "structs"
+
+// HostLayout marks a struct as using host memory layout.
+// See [structs.HostLayout] in Go 1.23 or later.
+type HostLayout = structs.HostLayout

cm/layout_test.go → cm/hostlayout_test.go

@@ -10,6 +10,7 @@ import (
 
 func TestFieldAlignment(t *testing.T) {
 	var v1 struct {
+		_   HostLayout
 		_   bool
 		_   [0][7]byte
 		u64 uint64
@@ -22,6 +23,7 @@ func TestFieldAlignment(t *testing.T) {
 	}
 
 	var v2 struct {
+		_ HostLayout
 		_ bool
 		_ [0][7]byte
 		_ [0][51]float64
@@ -40,6 +42,7 @@ func TestFieldAlignment(t *testing.T) {
 
 	// size 1
 	var v3 struct {
+		_ HostLayout
 		_ struct{}
 		b bool // offset 0
 	}
@@ -52,6 +55,7 @@ func TestFieldAlignment(t *testing.T) {
 
 	// size 0
 	var v4 struct {
+		_ HostLayout
 		_ [0]uint32
 		b bool // offset 0!
 	}

cm/list.go

@@ -27,6 +27,7 @@ func ToList[S ~[]T, T any](s S) List[T] {
 // It is intended to be embedded in a [List], so embedding types maintain
 // the methods defined on this type.
 type list[T any] struct {
+	_    HostLayout
 	data *T
 	len  uint
 }

cm/option.go

@@ -25,6 +25,7 @@ func Some[T any](v T) Option[T] {
 // The first byte is a bool representing none or some,
 // followed by storage for the associated type T.
 type option[T any] struct {
+	_      HostLayout
 	isSome bool
 	some   T
 }

cm/result.go

@@ -21,6 +21,7 @@ type Result[Shape, OK, Err any] struct{ result[Shape, OK, Err] }
 
 // result represents the internal representation of a Component Model result type.
 type result[Shape, OK, Err any] struct {
+	_     HostLayout
 	isErr bool
 	_     [0]OK
 	_     [0]Err

cm/result_test.go

@@ -183,6 +183,7 @@ func TestIssue95Struct(t *testing.T) {
 	type (
 		// structResult  Result[structVariant, stringStruct, structVariant]
 		stringStruct struct {
+			_ HostLayout
 			// i int
 			s string
 		}

cm/tuple.go

@@ -4,6 +4,7 @@ package cm
 //
 // [Component Model tuple]: https://component-model.bytecodealliance.org/design/wit.html#tuples
 type Tuple[T0, T1 any] struct {
+	_  HostLayout
 	F0 T0
 	F1 T1
 }
@@ -12,6 +13,7 @@ type Tuple[T0, T1 any] struct {
 //
 // [Component Model tuple]: https://component-model.bytecodealliance.org/design/wit.html#tuples
 type Tuple3[T0, T1, T2 any] struct {
+	_  HostLayout
 	F0 T0
 	F1 T1
 	F2 T2
@@ -21,6 +23,7 @@ type Tuple3[T0, T1, T2 any] struct {
 //
 // [Component Model tuple]: https://component-model.bytecodealliance.org/design/wit.html#tuples
 type Tuple4[T0, T1, T2, T3 any] struct {
+	_  HostLayout
 	F0 T0
 	F1 T1
 	F2 T2
@@ -31,6 +34,7 @@ type Tuple4[T0, T1, T2, T3 any] struct {
 //
 // [Component Model tuple]: https://component-model.bytecodealliance.org/design/wit.html#tuples
 type Tuple5[T0, T1, T2, T3, T4 any] struct {
+	_  HostLayout
 	F0 T0
 	F1 T1
 	F2 T2
@@ -42,6 +46,7 @@ type Tuple5[T0, T1, T2, T3, T4 any] struct {
 //
 // [Component Model tuple]: https://component-model.bytecodealliance.org/design/wit.html#tuples
 type Tuple6[T0, T1, T2, T3, T4, T5 any] struct {
+	_  HostLayout
 	F0 T0
 	F1 T1
 	F2 T2
@@ -54,6 +59,7 @@ type Tuple6[T0, T1, T2, T3, T4, T5 any] struct {
 //
 // [Component Model tuple]: https://component-model.bytecodealliance.org/design/wit.html#tuples
 type Tuple7[T0, T1, T2, T3, T4, T5, T6 any] struct {
+	_  HostLayout
 	F0 T0
 	F1 T1
 	F2 T2
@@ -67,6 +73,7 @@ type Tuple7[T0, T1, T2, T3, T4, T5, T6 any] struct {
 //
 // [Component Model tuple]: https://component-model.bytecodealliance.org/design/wit.html#tuples
 type Tuple8[T0, T1, T2, T3, T4, T5, T6, T7 any] struct {
+	_  HostLayout
 	F0 T0
 	F1 T1
 	F2 T2
@@ -81,6 +88,7 @@ type Tuple8[T0, T1, T2, T3, T4, T5, T6, T7 any] struct {
 //
 // [Component Model tuple]: https://component-model.bytecodealliance.org/design/wit.html#tuples
 type Tuple9[T0, T1, T2, T3, T4, T5, T6, T7, T8 any] struct {
+	_  HostLayout
 	F0 T0
 	F1 T1
 	F2 T2
@@ -96,6 +104,7 @@ type Tuple9[T0, T1, T2, T3, T4, T5, T6, T7, T8 any] struct {
 //
 // [Component Model tuple]: https://component-model.bytecodealliance.org/design/wit.html#tuples
 type Tuple10[T0, T1, T2, T3, T4, T5, T6, T7, T8, T9 any] struct {
+	_  HostLayout
 	F0 T0
 	F1 T1
 	F2 T2
@@ -112,6 +121,7 @@ type Tuple10[T0, T1, T2, T3, T4, T5, T6, T7, T8, T9 any] struct {
 //
 // [Component Model tuple]: https://component-model.bytecodealliance.org/design/wit.html#tuples
 type Tuple11[T0, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10 any] struct {
+	_   HostLayout
 	F0  T0
 	F1  T1
 	F2  T2
@@ -129,6 +139,7 @@ type Tuple11[T0, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10 any] struct {
 //
 // [Component Model tuple]: https://component-model.bytecodealliance.org/design/wit.html#tuples
 type Tuple12[T0, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11 any] struct {
+	_   HostLayout
 	F0  T0
 	F1  T1
 	F2  T2
@@ -147,6 +158,7 @@ type Tuple12[T0, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11 any] struct {
 //
 // [Component Model tuple]: https://component-model.bytecodealliance.org/design/wit.html#tuples
 type Tuple13[T0, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12 any] struct {
+	_   HostLayout
 	F0  T0
 	F1  T1
 	F2  T2
@@ -166,6 +178,7 @@ type Tuple13[T0, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12 any] struct {
 //
 // [Component Model tuple]: https://component-model.bytecodealliance.org/design/wit.html#tuples
 type Tuple14[T0, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13 any] struct {
+	_   HostLayout
 	F0  T0
 	F1  T1
 	F2  T2
@@ -186,6 +199,7 @@ type Tuple14[T0, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13 any] str
 //
 // [Component Model tuple]: https://component-model.bytecodealliance.org/design/wit.html#tuples
 type Tuple15[T0, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14 any] struct {
+	_   HostLayout
 	F0  T0
 	F1  T1
 	F2  T2
@@ -207,6 +221,7 @@ type Tuple15[T0, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14 any
 //
 // [Component Model tuple]: https://component-model.bytecodealliance.org/design/wit.html#tuples
 type Tuple16[T0, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15 any] struct {
+	_   HostLayout
 	F0  T0
 	F1  T1
 	F2  T2

cm/tuple_test.go

@@ -6,11 +6,12 @@ import (
 )
 
 func TestTuple(t *testing.T) {
-	_ = Tuple[string, bool]{"hello", false}
-	_ = Tuple3[string, bool, uint8]{"hello", false, 1}
-	_ = Tuple4[string, bool, uint8, uint16]{"hello", false, 1, 32000}
-	_ = Tuple5[string, bool, uint8, uint16, uint32]{"hello", false, 1, 32000, 1_000_000}
-	_ = Tuple6[string, bool, uint8, uint16, uint32, uint64]{"hello", false, 1, 32000, 1_000_000, 5_000_000_000}
-	_ = Tuple7[string, bool, uint8, uint16, uint32, uint64, float32]{"hello", false, math.MaxUint8, math.MaxUint16, math.MaxUint32, math.MaxUint64, math.MaxFloat32}
-	_ = Tuple8[string, bool, uint8, uint16, uint32, uint64, float32, float64]{"hello", false, math.MaxUint8, math.MaxUint16, math.MaxUint32, math.MaxUint64, math.MaxFloat32, math.MaxFloat64}
+	var HL HostLayout
+	_ = Tuple[string, bool]{HL, "hello", false}
+	_ = Tuple3[string, bool, uint8]{HL, "hello", false, 1}
+	_ = Tuple4[string, bool, uint8, uint16]{HL, "hello", false, 1, 32000}
+	_ = Tuple5[string, bool, uint8, uint16, uint32]{HL, "hello", false, 1, 32000, 1_000_000}
+	_ = Tuple6[string, bool, uint8, uint16, uint32, uint64]{HL, "hello", false, 1, 32000, 1_000_000, 5_000_000_000}
+	_ = Tuple7[string, bool, uint8, uint16, uint32, uint64, float32]{HL, "hello", false, math.MaxUint8, math.MaxUint16, math.MaxUint32, math.MaxUint64, math.MaxFloat32}
+	_ = Tuple8[string, bool, uint8, uint16, uint32, uint64, float32, float64]{HL, "hello", false, math.MaxUint8, math.MaxUint16, math.MaxUint32, math.MaxUint64, math.MaxFloat32, math.MaxFloat64}
 }

cm/variant.go

@@ -47,6 +47,7 @@ func Case[T any, V ~struct{ variant[Tag, Shape, Align] }, Tag Discriminant, Shap
 // variant is the internal representation of a Component Model variant.
 // Shape and Align must be non-zero sized types.
 type variant[Tag Discriminant, Shape, Align any] struct {
+	_    HostLayout
 	tag  Tag
 	_    [0]Align
 	data Shape // [unsafe.Sizeof(*(*Shape)(unsafe.Pointer(nil)))]byte

testdata/example/non-flat-params.wit

@@ -57,6 +57,8 @@ interface corner-case {
 		u17-void: func(a: u8, b: u8, c: u8, d: u8, e: u8, f: u8, g: u8, h: u8, i: u8, j: u8, k: u8, l: u8, m: u8, n: u8, o: u8, p: u8, q: u8);
 		u17-u8-u8: func(a: u8, b: u8, c: u8, d: u8, e: u8, f: u8, g: u8, h: u8, i: u8, j: u8, k: u8, l: u8, m: u8, n: u8, o: u8, p: u8, q: u8) -> (r0: u8, r1: u8);
 	}
+
+	reserved-names: func(%bool: u8, int8: u8, uint8: u8, int16: u8, uint16: u8, int32: u8, uint32: u8, %f32: u8, %f64: u8, %string: u8, %record: u8, struct: u8, %world: u8, %interface: u8, %option: u8, %package: u8, %result: u8) -> (r0: u8, r1: u8);
 }
 
 world imports {

testdata/example/non-flat-params.wit.json

@@ -1641,6 +1641,90 @@
               "type": "u8"
             }
           ]
+        },
+        "reserved-names": {
+          "name": "reserved-names",
+          "kind": "freestanding",
+          "params": [
+            {
+              "name": "bool",
+              "type": "u8"
+            },
+            {
+              "name": "int8",
+              "type": "u8"
+            },
+            {
+              "name": "uint8",
+              "type": "u8"
+            },
+            {
+              "name": "int16",
+              "type": "u8"
+            },
+            {
+              "name": "uint16",
+              "type": "u8"
+            },
+            {
+              "name": "int32",
+              "type": "u8"
+            },
+            {
+              "name": "uint32",
+              "type": "u8"
+            },
+            {
+              "name": "f32",
+              "type": "u8"
+            },
+            {
+              "name": "f64",
+              "type": "u8"
+            },
+            {
+              "name": "string",
+              "type": "u8"
+            },
+            {
+              "name": "record",
+              "type": "u8"
+            },
+            {
+              "name": "struct",
+              "type": "u8"
+            },
+            {
+              "name": "world",
+              "type": "u8"
+            },
+            {
+              "name": "interface",
+              "type": "u8"
+            },
+            {
+              "name": "option",
+              "type": "u8"
+            },
+            {
+              "name": "package",
+              "type": "u8"
+            },
+            {
+              "name": "result",
+              "type": "u8"
+            }
+          ],
+          "results": [
+            {
+              "name": "r0",
+              "type": "u8"
+            },
+            {
+              "name": "r1",
+              "type": "u8"
+            }
+          ]
         }
       },
       "package": 0

testdata/example/non-flat-params.wit.json.golden.wit

@@ -44,6 +44,7 @@ interface corner-case {
 	u16-x17-u8: func(a: u8, b: u8, c: u8, d: u8, e: u8, f: u8, g: u8, h: u8, i: u8, j: u8, k: u8, l: u8, m: u8, n: u8, o: u8, p: u8) -> (a: u8, b: u8, c: u8, d: u8, e: u8, f: u8, g: u8, h: u8, i: u8, j: u8, k: u8, l: u8, m: u8, n: u8, o: u8, p: u8, q: u8);
 	u17-void: func(a: u8, b: u8, c: u8, d: u8, e: u8, f: u8, g: u8, h: u8, i: u8, j: u8, k: u8, l: u8, m: u8, n: u8, o: u8, p: u8, q: u8);
 	u17-u8-u8: func(a: u8, b: u8, c: u8, d: u8, e: u8, f: u8, g: u8, h: u8, i: u8, j: u8, k: u8, l: u8, m: u8, n: u8, o: u8, p: u8, q: u8) -> (r0: u8, r1: u8);
+	reserved-names: func(%bool: u8, int8: u8, uint8: u8, int16: u8, uint16: u8, int32: u8, uint32: u8, %f32: u8, %f64: u8, %string: u8, %record: u8, struct: u8, %world: u8, %interface: u8, %option: u8, %package: u8, %result: u8) -> (r0: u8, r1: u8);
 }
 
 world imports {

wit/bindgen/generator.go

@@ -704,7 +704,9 @@ func (g *generator) primitiveRep(p wit.Primitive) string {
 func (g *generator) recordRep(file *gen.File, dir wit.Direction, r *wit.Record, goName string) string {
 	exported := len(goName) == 0 || token.IsExported(goName)
 	var b strings.Builder
-	b.WriteString("struct {")
+	cm := file.Import(g.opts.cmPackage)
+	b.WriteString("struct {\n")
+	stringio.Write(&b, "_ ", cm, ".HostLayout")
 	for i, f := range r.Fields {
 		if i == 0 || i > 0 && f.Docs.Contents != "" {
 			b.WriteRune('\n')
@@ -1728,7 +1730,8 @@ func (g *generator) defineImportedFunction(_ wit.Ident, f *wit.Function, decl fu
 			if i > 0 {
 				b.WriteString(", ")
 			}
-			b.WriteString(p.name)
+			// compound parameter struct field names are identical to parameter names
+			stringio.Write(&b, p.name, ": ", p.name)
 		}
 		b.WriteString(" }\n")
 	} else if len(callParams) > 0 {