feat: add basic support for the multi-value proposal

Author: JairusSW

cli/options.json

@@ -219,6 +219,7 @@
       " threads             Threading and atomic operations.",
       " simd                SIMD types and operations.",
       " reference-types     Reference types and operations.",
+      " multi-value         Multi value types.",
       " gc                  Garbage collection (WIP).",
       " stringref           String reference types.",
       " relaxed-simd        Relaxed SIMD operations.",
@@ -227,7 +228,6 @@
     "TODO_doesNothingYet": [
       " exception-handling  Exception handling.",
       " tail-calls          Tail call operations.",
-      " multi-value         Multi value types.",
       " memory64            Memory64 operations.",
       " extended-const      Extended const expressions."
     ],

src/ast.ts

@@ -50,6 +50,7 @@ export const enum NodeKind {
   // types
   NamedType,
   FunctionType,
+  TupleType,
   TypeName,
   TypeParameter,
   Parameter,
@@ -161,6 +162,14 @@ export abstract class Node {
     return new FunctionTypeNode(parameters, returnType, explicitThisType, isNullable, range);
   }
 
+  static createTupleType(
+    elements: TypeNode[],
+    isNullable: bool,
+    range: Range
+  ): TupleTypeNode {
+    return new TupleTypeNode(elements, isNullable, range);
+  }
+
   static createOmittedType(
     range: Range
   ): NamedTypeNode {
@@ -862,6 +871,9 @@ export abstract class TypeNode extends Node {
       if (functionTypeNode.returnType.hasGenericComponent(typeParameterNodes)) return true;
       let explicitThisType = functionTypeNode.explicitThisType;
       if (explicitThisType && explicitThisType.hasGenericComponent(typeParameterNodes)) return true;
+    } else if (this.kind == NodeKind.TupleType) {
+      let tupleTypeNode = <TupleTypeNode>changetype<TypeNode>(this);
+      if (tupleTypeNode.elements.some((v) => v.hasGenericComponent(typeParameterNodes))) return true;
     } else {
       assert(false);
     }
@@ -928,6 +940,20 @@ export class FunctionTypeNode extends TypeNode {
   }
 }
 
+/** Represents a tuple type. */
+export class TupleTypeNode extends TypeNode {
+  constructor(
+    /** Tuple elements. */
+    public elements: TypeNode[],
+    /** Whether nullable or not. */
+    isNullable: bool,
+    /** Source range. */
+    range: Range
+  ) {
+    super(NodeKind.TupleType, isNullable, range);
+  }
+}
+
 /** Represents a type parameter. */
 export class TypeParameterNode extends Node {
   constructor(