Preserve synthesized node ranges across API serialization

packages/typescript/src/api/node/encoder.ts

@@ -226,8 +226,8 @@ export function encodeNode(node: Node): Uint8Array {
         const data = getNodeData(node, strs, extendedDataValues, structuredWriter);
         nodeValues.push(
             node.kind,
-            node.pos >= 0 ? node.pos : 0,
-            node.end >= 0 ? node.end : 0,
+            node.pos,
+            node.end,
             0, // next (filled in later)
             parentIndex,
             data,
@@ -259,8 +259,8 @@ export function encodeNode(node: Node): Uint8Array {
 
         nodeValues.push(
             KIND_NODE_LIST,
-            list.pos >= 0 ? list.pos : 0,
-            list.end >= 0 ? list.end : 0,
+            list.pos,
+            list.end,
             0, // next
             parentIndex,
             list.length, // data for NodeList is its length
@@ -304,8 +304,8 @@ export function encodeNode(node: Node): Uint8Array {
     const rootData = getNodeData(node, strs, extendedDataValues, structuredWriter);
     nodeValues.push(
         node.kind,
-        node.pos >= 0 ? node.pos : 0,
-        node.end >= 0 ? node.end : 0,
+        node.pos,
+        node.end,
         0,
         0,
         rootData,

packages/typescript/src/api/node/node.generated.ts

@@ -58,11 +58,11 @@ export class RemoteNodeList extends Array<RemoteNode> implements NodeArray<Remot
     private _cursorNodeIndex: number = 0;
 
     get pos(): number {
-        return this.view.getUint32(this._byteIndex + NODE_OFFSET_POS, true);
+        return this.view.getInt32(this._byteIndex + NODE_OFFSET_POS, true);
     }
 
     get end(): number {
-        return this.view.getUint32(this._byteIndex + NODE_OFFSET_END, true);
+        return this.view.getInt32(this._byteIndex + NODE_OFFSET_END, true);
     }
 
     get next(): number {

packages/typescript/test/async/api.test.ts

@@ -39,25 +39,30 @@ import {
     type RootedFilePath,
     type SourceFile,
     SyntaxKind,
+    TokenFlags,
     tryGetAmbientModuleNameFromSymbolName,
     unescapeLeadingUnderscores,
 } from "@typescript/typescript/ast";
 import {
     cloneNode,
     createArrayTypeNode,
+    createCallExpression,
+    createExpressionStatement,
     createFunctionTypeNode,
     createIdentifier,
     createKeywordTypeNode,
     createNumericLiteral,
     createParameterDeclaration,
     createSourceFile,
+    createStringLiteral,
     createToken,
     createTypeAliasDeclaration,
     createTypeReferenceNode,
     createUnionTypeNode,
     createVariableDeclaration,
     createVariableDeclarationList,
     createVariableStatement,
+    updateSourceFile,
 } from "@typescript/typescript/ast/factory";
 import { visitEachChild } from "@typescript/typescript/ast/visitor";
 import {
@@ -7964,6 +7969,20 @@ export const obj = { m: 1, s: "hi", b: true };
         assert.strictEqual(text, "string");
     });
 
+    test("synthesized nodes do not acquire source comments", async () => {
+        await using api = spawnAPI();
+        await using lease = await api.createSourceFile("/test.ts", "/** leading comment */\nfoo();\n/* @__PURE__ */ baz();\n");
+        const { sourceFile } = lease;
+        const added = createExpressionStatement(
+            createCallExpression(createIdentifier("bar"), undefined, undefined, [createStringLiteral("x", TokenFlags.None)], NodeFlags.None),
+        );
+        const updated = updateSourceFile(sourceFile, [added, ...sourceFile.statements], sourceFile.endOfFileToken);
+        const expected = 'bar("x");\n/** leading comment */\nfoo();\n/* @__PURE__ */ baz();\n';
+
+        assert.strictEqual(await api.printer.printNode(updated), expected);
+        assert.strictEqual(await api.printer.printFile(updated), expected);
+    });
+
     test("printFile", async () => {
         await using api = spawnAPI(emitterFiles);
 

packages/typescript/test/encoder.test.ts

@@ -74,6 +74,17 @@ function decode(data: Uint8Array): RemoteSourceFile {
 }
 
 describe("Encoder", { concurrency }, () => {
+    test("preserves synthesized node and list ranges", () => {
+        const statement = createExpressionStatement(createIdentifier("x"));
+        const sf = makeSF("", "/test.ts", [statement]);
+        const decoded = decode(encodeSourceFile(sf));
+
+        for (const range of [decoded, decoded.statements!, decoded.statements!.at(0)!, decoded.endOfFileToken!]) {
+            assert.strictEqual(range.pos, -1);
+            assert.strictEqual(range.end, -1);
+        }
+    });
+
     test("encodes empty source file", () => {
         const sf = makeSF("", "/test.ts", []);
 

packages/typescript/test/sync/api.test.ts

@@ -47,25 +47,30 @@ import {
     type RootedFilePath,
     type SourceFile,
     SyntaxKind,
+    TokenFlags,
     tryGetAmbientModuleNameFromSymbolName,
     unescapeLeadingUnderscores,
 } from "@typescript/typescript/ast";
 import {
     cloneNode,
     createArrayTypeNode,
+    createCallExpression,
+    createExpressionStatement,
     createFunctionTypeNode,
     createIdentifier,
     createKeywordTypeNode,
     createNumericLiteral,
     createParameterDeclaration,
     createSourceFile,
+    createStringLiteral,
     createToken,
     createTypeAliasDeclaration,
     createTypeReferenceNode,
     createUnionTypeNode,
     createVariableDeclaration,
     createVariableDeclarationList,
     createVariableStatement,
+    updateSourceFile,
 } from "@typescript/typescript/ast/factory";
 import { visitEachChild } from "@typescript/typescript/ast/visitor";
 import {
@@ -7765,6 +7770,20 @@ export const obj = { m: 1, s: "hi", b: true };
         assert.strictEqual(text, "string");
     });
 
+    test("synthesized nodes do not acquire source comments", () => {
+        using api = spawnAPI();
+        using lease = api.createSourceFile("/test.ts", "/** leading comment */\nfoo();\n/* @__PURE__ */ baz();\n");
+        const { sourceFile } = lease;
+        const added = createExpressionStatement(
+            createCallExpression(createIdentifier("bar"), undefined, undefined, [createStringLiteral("x", TokenFlags.None)], NodeFlags.None),
+        );
+        const updated = updateSourceFile(sourceFile, [added, ...sourceFile.statements], sourceFile.endOfFileToken);
+        const expected = 'bar("x");\n/** leading comment */\nfoo();\n/* @__PURE__ */ baz();\n';
+
+        assert.strictEqual(api.printer.printNode(updated), expected);
+        assert.strictEqual(api.printer.printFile(updated), expected);
+    });
+
     test("printFile", () => {
         using api = spawnAPI(emitterFiles);
 

tools/scripts/tsc/generate-encoder.ts

@@ -1535,11 +1535,11 @@ function emitRemoteNodeList(w: CodeWriter) {
     w.write(`    private _cursorNodeIndex: number = 0;`);
     w.write(``);
     w.write(`    get pos(): number {`);
-    w.write(`        return this.view.getUint32(this._byteIndex + NODE_OFFSET_POS, true);`);
+    w.write(`        return this.view.getInt32(this._byteIndex + NODE_OFFSET_POS, true);`);
     w.write(`    }`);
     w.write(``);
     w.write(`    get end(): number {`);
-    w.write(`        return this.view.getUint32(this._byteIndex + NODE_OFFSET_END, true);`);
+    w.write(`        return this.view.getInt32(this._byteIndex + NODE_OFFSET_END, true);`);
     w.write(`    }`);
     w.write(``);
     w.write(`    get next(): number {`);

tsc/internal/api/encoder/decoder.go

@@ -149,8 +149,8 @@ func (d *astDecoder) decode() (*ast.Node, error) {
 	// Process bottom-up so children exist before parents.
 	for i := d.nodeCount - 1; i >= 1; i-- {
 		kind := d.nodeField(i, NodeOffsetKind)
-		pos := d.nodeField(i, NodeOffsetPos)
-		end := d.nodeField(i, NodeOffsetEnd)
+		pos := int32(d.nodeField(i, NodeOffsetPos))
+		end := int32(d.nodeField(i, NodeOffsetEnd))
 		data := d.nodeField(i, NodeOffsetData)
 		childIndices := d.collectChildren(i)
 

tsc/internal/api/encoder/decoder_test.go

@@ -2,6 +2,7 @@ package encoder_test
 
 import (
 	"bytes"
+	"encoding/binary"
 	"os"
 	"path/filepath"
 	"testing"
@@ -37,6 +38,26 @@ func TestDecodeSourceFile_Basic(t *testing.T) {
 	assert.Assert(t, decoded.EndOfFileToken != nil)
 }
 
+func TestDecodeSourceFile_SynthesizedRanges(t *testing.T) {
+	t.Parallel()
+	sf := parseSourceFile("foo();")
+	synthesized := core.NewTextRange(-1, -1)
+	buf, _, err := encoder.EncodeSourceFile(sf)
+	assert.NilError(t, err)
+	nodesOffset := int(binary.LittleEndian.Uint32(buf[encoder.HeaderOffsetNodes:]))
+	for offset := nodesOffset + encoder.NodeSize; offset < len(buf); offset += encoder.NodeSize {
+		binary.LittleEndian.PutUint32(buf[offset+encoder.NodeOffsetPos:], ^uint32(0))
+		binary.LittleEndian.PutUint32(buf[offset+encoder.NodeOffsetEnd:], ^uint32(0))
+	}
+	decoded, err := encoder.DecodeSourceFile(buf)
+	assert.NilError(t, err)
+
+	assert.Equal(t, decoded.AsNode().Loc, synthesized)
+	assert.Equal(t, decoded.Statements.Loc, synthesized)
+	assert.Equal(t, decoded.Statements.Nodes[0].Loc, synthesized)
+	assert.Equal(t, decoded.EndOfFileToken.Loc, synthesized)
+}
+
 func TestDecodeSourceFile_Metadata(t *testing.T) {
 	t.Parallel()