wit, cmd/wit-bindgen-go: WIT tree shaking

This enables WIT tree-shaking by world or interface, as a precursor for Go package-level component metadata.

wit/bindgen: oops

wit/bindgen: add WIT generation for each WIT interface (Go package)

Currently disabled.

wit/bindgen: cgo + linker tricks WIP

wit: fix typo

wit/bindgen: typo

wit: type aliases force transitive dependency on the dependencies of their parent interface

wit: prepare for filtering interface contents

wit: remove ConstrainTo

internal/wasm: stub linking section

wit/bindgen: generate .wasm.syso files in each Go package

Currently stubbed out (if false). Depends on tinygo-org/tinygo#4593

wit: revise package sorting algorithm

This enables wasi:http to sort before wasi:cli.

wit/bindgen: more cleanup (path -> pkgPath)

wit/bindgen: optionally generate WIT files for each Go package

cmd/wit-bindgen-go: --generate-wit option to generate WIT files for each Go package

wit/bindgen: generate synthetic worlds in the go:bindgen package namespace

cmd/wit-bindgen-go/cmd/generate/generate.go

@@ -28,7 +28,7 @@ var Command = &cli.Command{
 			Value:    "",
 			OnlyOnce: true,
 			Config:   cli.StringConfig{TrimSpace: true},
-			Usage:    "WIT world to generate, otherwise generate all worlds",
+			Usage:    "WIT world to generate, otherwise generate the first world",
 		},
 		&cli.StringFlag{
 			Name:      "out",
@@ -52,11 +52,15 @@ var Command = &cli.Command{
 			Value:    "",
 			OnlyOnce: true,
 			Config:   cli.StringConfig{TrimSpace: true},
-			Usage:    "Import path for the Component Model utility package, e.g. go.bytecodealliance.org/cm",
+			Usage:    "import path for the Component Model utility package, e.g. go.bytecodealliance.org/cm",
 		},
 		&cli.BoolFlag{
 			Name:  "versioned",
-			Usage: "emit versioned Go package(s) for each WIT version",
+			Usage: "emit versioned Go package(s) corresponding to WIT package version",
+		},
+		&cli.BoolFlag{
+			Name:  "generate-wit",
+			Usage: "generate a WIT file for each generated Go package corresponding to each WIT world or interface",
 		},
 		&cli.BoolFlag{
 			Name:  "dry-run",
@@ -68,16 +72,17 @@ var Command = &cli.Command{
 
 // Config is the configuration for the `generate` command.
 type config struct {
-	logger    logging.Logger
-	dryRun    bool
-	out       string
-	outPerm   os.FileMode
-	pkgRoot   string
-	world     string
-	cm        string
-	versioned bool
-	forceWIT  bool
-	path      string
+	logger      logging.Logger
+	dryRun      bool
+	out         string
+	outPerm     os.FileMode
+	pkgRoot     string
+	world       string
+	cm          string
+	versioned   bool
+	generateWIT bool
+	forceWIT    bool
+	path        string
 }
 
 func action(ctx context.Context, cmd *cli.Command) error {
@@ -94,10 +99,11 @@ func action(ctx context.Context, cmd *cli.Command) error {
 	packages, err := bindgen.Go(res,
 		bindgen.GeneratedBy(cmd.Root().Name),
 		bindgen.Logger(cfg.logger),
-		bindgen.World(cfg.world),
 		bindgen.PackageRoot(cfg.pkgRoot),
-		bindgen.Versioned(cfg.versioned),
+		bindgen.World(cfg.world),
 		bindgen.CMPackage(cfg.cm),
+		bindgen.Versioned(cfg.versioned),
+		bindgen.WIT(cfg.generateWIT),
 	)
 	if err != nil {
 		return err
@@ -141,6 +147,7 @@ func parseFlags(_ context.Context, cmd *cli.Command) (*config, error) {
 		cmd.String("world"),
 		cmd.String("cm"),
 		cmd.Bool("versioned"),
+		cmd.Bool("generate-wit"),
 		cmd.Bool("force-wit"),
 		path,
 	}, nil

cmd/wit-bindgen-go/cmd/wit/wit.go

@@ -21,7 +21,15 @@ var Command = &cli.Command{
 			Value:    "",
 			OnlyOnce: true,
 			Config:   cli.StringConfig{TrimSpace: true},
-			Usage:    "WIT world to generate, otherwise generate all worlds",
+			Usage:    "WIT world to emit, otherwise emit all worlds",
+		},
+		&cli.StringFlag{
+			Name:     "interface",
+			Aliases:  []string{"i"},
+			Value:    "",
+			OnlyOnce: true,
+			Config:   cli.StringConfig{TrimSpace: true},
+			Usage:    "WIT interface to emit, otherwise emit all interfaces",
 		},
 	},
 	Action: action,
@@ -32,19 +40,30 @@ func action(ctx context.Context, cmd *cli.Command) error {
 	if err != nil {
 		return err
 	}
+
 	res, err := witcli.LoadWIT(ctx, path, cmd.Reader, cmd.Bool("force-wit"))
 	if err != nil {
 		return err
 	}
+
 	var w *wit.World
-	world := cmd.String("world")
-	if world != "" {
+	if world := cmd.String("world"); world != "" {
 		w = findWorld(res, world)
 		if w == nil {
 			return fmt.Errorf("world %s not found", world)
 		}
 	}
-	fmt.Print(res.WIT(w, ""))
+
+	var i *wit.Interface
+	if face := cmd.String("interface"); face != "" {
+		i = findInterface(res, face)
+		if i == nil {
+			return fmt.Errorf("interface %s not found", face)
+		}
+	}
+
+	filter := wit.Filter(w, i)
+	fmt.Print(res.WIT(filter, ""))
 	return nil
 }
 
@@ -56,3 +75,12 @@ func findWorld(r *wit.Resolve, pattern string) *wit.World {
 	}
 	return nil
 }
+
+func findInterface(r *wit.Resolve, pattern string) *wit.Interface {
+	for _, i := range r.Interfaces {
+		if i.Match(pattern) {
+			return i
+		}
+	}
+	return nil
+}

internal/memoize/memoize.go

@@ -0,0 +1,16 @@
+package memoize
+
+// Function memoizes f, caching unique values of k.
+// Initial calls to the resulting function will call f(k), then cache and return v.
+// Subsequent calls will return the cached value for k.
+func Function[F func(K) V, K comparable, V any](f F) F {
+	m := make(map[K]V)
+	return func(k K) V {
+		if v, ok := m[k]; ok {
+			return v
+		}
+		v := f(k)
+		m[k] = v
+		return v
+	}
+}

internal/wasm/section.go

@@ -1,5 +1,11 @@
 package wasm
 
+import (
+	"bytes"
+
+	"go.bytecodealliance.org/internal/wasm/uleb128"
+)
+
 // SectionID represents a WebAssembly [section SectionID].
 //
 // [section SectionID]: https://webassembly.github.io/spec/core/binary/modules.html#sections
@@ -47,6 +53,34 @@ func (*CustomSection) SectionID() SectionID {
 
 // SectionContents implements the [Section] interface.
 func (s *CustomSection) SectionContents() ([]byte, error) {
-	// TODO: encode name correctly
-	return append([]byte(s.Name), s.Contents...), nil
+	var buf bytes.Buffer
+	_, err := WriteString(&buf, s.Name)
+	if err != nil {
+		return nil, err
+	}
+	_, err = buf.Write(s.Contents)
+	return buf.Bytes(), err
+}
+
+type LinkingSection struct{}
+
+// SectionID implements the [Section] interface.
+func (*LinkingSection) SectionID() SectionID {
+	return SectionCustom
+}
+
+// SectionContents implements the [Section] interface.
+func (s *LinkingSection) SectionContents() ([]byte, error) {
+	var buf bytes.Buffer
+	custom := &CustomSection{Name: "linking"}
+	contents, err := custom.SectionContents()
+	if err != nil {
+		return nil, err
+	}
+	_, err = buf.Write(contents)
+	if err != nil {
+		return nil, err
+	}
+	_, err = uleb128.Write(&buf, 2) // linking section version 2
+	return buf.Bytes(), err
 }