Merge pull request #277 from bytecodealliance/ydnar/async

all: initial support for async types

Author: ydnar

.github/workflows/test.yaml

@@ -14,7 +14,7 @@ on:
 
 env:
   go-modules: ./... ./cm/...
-  wasm-tools-version: "1.219.1"
+  wasm-tools-version: "1.222.0"
   wasmtime-version: "26.0.0"
 
 jobs:

CHANGELOG.md

@@ -10,7 +10,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 
 ### Changed
 
-- Incremental support for Component Model async types `stream<T>` and `future<T>`.
+- Initial support for Component Model [async](https://github.com/WebAssembly/component-model/blob/main/design/mvp/Async.md) types `stream`, `future`, and `error-context`.
+- Breaking: generated `*.wasm.go` files will now have correct WIT kebab-case base name. Interfaces or worlds with `-` in their name will require removal of the previous `*.wasm.go` files.
 - Dropped support for TinyGo v0.32.0.
 
 ## [v0.5.0] — 2024-12-14

cm/CHANGELOG.md

@@ -2,6 +2,12 @@
 
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/), and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [Unreleased]
+
+### Added
+
+- Initial support for Component Model [async](https://github.com/WebAssembly/component-model/blob/main/design/mvp/Async.md) types `stream`, `future`, and `error-context`.
+
 ## [v0.1.0] — 2024-12-14
 
 Initial version, extracted into module [`go.bytecodealliance.org/cm`](https://pkg.go.dev/go.bytecodealliance.org/cm).

cm/empty.s

@@ -0,0 +1,3 @@
+// This file exists for testing this package without WebAssembly,
+// allowing empty function bodies with a //go:wasmimport directive.
+// See https://pkg.go.dev/cmd/compile for more information.

cm/error.go

@@ -0,0 +1,48 @@
+package cm
+
+import "unsafe"
+
+// ErrorContext represents the Component Model [error-context] type,
+// an immutable, non-deterministic, host-defined value meant to aid in debugging.
+//
+// [error-context]: https://github.com/WebAssembly/component-model/blob/main/design/mvp/Explainer.md#error-context-type
+type ErrorContext struct {
+	_ HostLayout
+	errorContext
+}
+
+type errorContext uint32
+
+// Error implements the [error] interface. It returns the debug message associated with err.
+func (err errorContext) Error() string {
+	return err.DebugMessage()
+}
+
+// String implements [fmt.Stringer].
+func (err errorContext) String() string {
+	return err.DebugMessage()
+}
+
+// DebugMessage represents the Canonical ABI [error-context.debug-message] function.
+//
+// [error-context.debug-message]: https://github.com/WebAssembly/component-model/blob/main/design/mvp/Explainer.md#error-contextdebug-message
+func (err errorContext) DebugMessage() string {
+	var s string
+	errorContextDebugMessage(err, unsafe.Pointer(&s))
+	return s
+}
+
+//go:wasmimport canon error-context.debug-message
+//go:noescape
+func errorContextDebugMessage(err errorContext, msg unsafe.Pointer)
+
+// Drop represents the Canonical ABI [error-context.drop] function.
+//
+// [error-context.drop]: https://github.com/WebAssembly/component-model/blob/main/design/mvp/Explainer.md#error-contextdrop
+func (err errorContext) Drop() {
+	errorContextDrop(err)
+}
+
+//go:wasmimport canon error-context.drop
+//go:noescape
+func errorContextDrop(err errorContext)

cm/future.go

@@ -0,0 +1,15 @@
+package cm
+
+// Future represents the Component Model [future] type.
+// A future is a special case of stream. In non-error cases,
+// a future delivers exactly one value before being automatically closed.
+//
+// [future]: https://github.com/WebAssembly/component-model/blob/main/design/mvp/Explainer.md#asynchronous-value-types
+type Future[T any] struct {
+	_ HostLayout
+	future[T]
+}
+
+type future[T any] uint32
+
+// TODO: implement methods on type future

cm/stream.go

@@ -0,0 +1,15 @@
+package cm
+
+// Stream represents the Component Model [stream] type.
+// A stream is a special case of stream. In non-error cases,
+// a stream delivers exactly one value before being automatically closed.
+//
+// [stream]: https://github.com/WebAssembly/component-model/blob/main/design/mvp/Explainer.md#asynchronous-value-types
+type Stream[T any] struct {
+	_ HostLayout
+	stream[T]
+}
+
+type stream[T any] uint32
+
+// TODO: implement methods on type stream

testdata/codegen/error-context.wit

@@ -0,0 +1,13 @@
+package foo:foo;
+
+interface error-contexts {
+  type foo = error-context;
+
+  bar: func(x: foo, y: error-context, z: future<error-context>) -> result<stream<error-context>, error-context>;
+}
+
+world foo {
+  import error-contexts;
+  export error-contexts;
+}
+

testdata/codegen/error-context.wit.json

@@ -0,0 +1,105 @@
+{
+  "worlds": [
+    {
+      "name": "foo",
+      "imports": {
+        "interface-0": {
+          "interface": {
+            "id": 0
+          }
+        }
+      },
+      "exports": {
+        "interface-0": {
+          "interface": {
+            "id": 0
+          }
+        }
+      },
+      "package": 0
+    }
+  ],
+  "interfaces": [
+    {
+      "name": "error-contexts",
+      "types": {
+        "foo": 0
+      },
+      "functions": {
+        "bar": {
+          "name": "bar",
+          "kind": "freestanding",
+          "params": [
+            {
+              "name": "x",
+              "type": 0
+            },
+            {
+              "name": "y",
+              "type": 1
+            },
+            {
+              "name": "z",
+              "type": 2
+            }
+          ],
+          "results": [
+            {
+              "type": 4
+            }
+          ]
+        }
+      },
+      "package": 0
+    }
+  ],
+  "types": [
+    {
+      "name": "foo",
+      "kind": "errorcontext",
+      "owner": {
+        "interface": 0
+      }
+    },
+    {
+      "name": null,
+      "kind": "errorcontext",
+      "owner": null
+    },
+    {
+      "name": null,
+      "kind": {
+        "future": 1
+      },
+      "owner": null
+    },
+    {
+      "name": null,
+      "kind": {
+        "stream": 1
+      },
+      "owner": null
+    },
+    {
+      "name": null,
+      "kind": {
+        "result": {
+          "ok": 3,
+          "err": 1
+        }
+      },
+      "owner": null
+    }
+  ],
+  "packages": [
+    {
+      "name": "foo:foo",
+      "interfaces": {
+        "error-contexts": 0
+      },
+      "worlds": {
+        "foo": 0
+      }
+    }
+  ]
+}

testdata/codegen/error-context.wit.json.golden.wit

@@ -0,0 +1,11 @@
+package foo:foo;
+
+interface error-contexts {
+	type foo = error-context;
+	bar: func(x: foo, y: error-context, z: future<error-context>) -> result<stream<error-context>, error-context>;
+}
+
+world foo {
+	import error-contexts;
+	export error-contexts;
+}