fix: missing source maps for hoisted imports (fix vitejs#16355)

packages/vite/src/node/ssr/__tests__/ssrTransform.spec.ts

@@ -341,6 +341,64 @@ test('sourcemap source', async () => {
  expect(map?.sourcesContent).toStrictEqual(['export const a = 1 /* */'])
 })
 
+test('sourcemap is correct for hoisted imports', async () => {
+ // Mapping from Base64 character to integer
+ const base64Chars =
+ 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'
+ const base64ToInt = Object.fromEntries(
+ base64Chars.split('').map((c, i) => [c, i]),
+ )
+
+ // Decode a single Base64 VLQ segment
+ function decodeVLQ(segment) {
+ const result: number[] = []
+ let cur = 0
+ let shift = 0
+ let continuation, sign, value
+
+ for (const char of segment) {
+ const integer = base64ToInt[char]
+
+ continuation = integer & 32
+ value = integer & 31
+ cur += value << shift
+ shift += 5
+
+ if (!continuation) {
+ sign = cur & 1
+ cur >>= 1
+ if (sign) {
+ cur = -cur
+ }
+ result.push(cur)
+ cur = 0
+ shift = 0
+ }
+ }
+
+ const [, , originalLine] = result
+ return originalLine
+ }
+
+ // Split the mappings string and decode each segment
+ function decodeMappings(mappings) {
+ const lines = mappings.split(';')
+ return lines.map((line) => line.split(',').map(decodeVLQ))
+ }
+
+ const map = (
+ await ssrTransform(
+ `\n\n\nimport { foo } from 'vue';`,
+ null,
+ 'input.js',
+ 'export const a = 1 /* */',
+ )
+ )?.map
+
+ const decodedMappings = decodeMappings(map?.mappings || '')
+ expect(decodedMappings[0]).toEqual([3])
+})
+
 test('overwrite bindings', async () => {
  expect(
  await ssrTransformSimpleCode(

packages/vite/src/node/ssr/ssrTransform.ts

@@ -92,10 +92,12 @@ async function ssrTransformScript(
  const declaredConst = new Set<string>()
 
  // hoist at the start of the file, after the hashbang
- const hoistIndex = code.match(hashbangRE)?.[0].length ?? 0
+ let hoistIndex = code.match(hashbangRE)?.[0].length ?? 0
 
  function defineImport(
  index: number,
+ start: number,
+ end: number,
  source: string,
  metadata?: DefineImportMetadata,
  ) {
@@ -113,12 +115,22 @@ async function ssrTransformScript(
 
  // There will be an error if the module is called before it is imported,
  // so the module import statement is hoisted to the top
- s.appendLeft(
- index,
+ s.update(
+ start,
+ end,
  `const ${importId} = await ${ssrImportKey}(${JSON.stringify(
  source,
  )}${metadataStr});\n`,
  )
+
+ if (start !== index) {
+ s.move(start, end, index)
+ }
+
+ if (index === hoistIndex) {
+ hoistIndex = end
+ }
+
  return importId
  }
 
@@ -136,15 +148,20 @@ async function ssrTransformScript(
  // import { baz } from 'foo' --> baz -> __import_foo__.baz
  // import * as ok from 'foo' --> ok -> __import_foo__
  if (node.type === 'ImportDeclaration') {
- const importId = defineImport(hoistIndex, node.source.value as string, {
- importedNames: node.specifiers
- .map((s) => {
- if (s.type === 'ImportSpecifier') return s.imported.name
- else if (s.type === 'ImportDefaultSpecifier') return 'default'
- })
- .filter(isDefined),
- })
- s.remove(node.start, node.end)
+ const importId = defineImport(
+ hoistIndex,
+ node.start,
+ node.end,
+ node.source.value as string,
+ {
+ importedNames: node.specifiers
+ .map((s) => {
+ if (s.type === 'ImportSpecifier') return s.imported.name
+ else if (s.type === 'ImportDefaultSpecifier') return 'default'
+ })
+ .filter(isDefined),
+ },
+ )
  for (const spec of node.specifiers) {
  if (spec.type === 'ImportSpecifier') {
  idToImportMap.set(
@@ -188,14 +205,16 @@ async function ssrTransformScript(
  // export { foo, bar } from './foo'
  const importId = defineImport(
  node.start,
+ node.start,
+ node.end,
  node.source.value as string,
  {
  importedNames: node.specifiers.map((s) => s.local.name),
  },
  )
  for (const spec of node.specifiers) {
  defineExport(
- node.start,
+ node.end,
  spec.exported.name,
  `${importId}.${spec.local.name}`,
  )
@@ -240,12 +259,16 @@ async function ssrTransformScript(
 
  // export * from './foo'
  if (node.type === 'ExportAllDeclaration') {
- s.remove(node.start, node.end)
- const importId = defineImport(node.start, node.source.value as string)
+ const importId = defineImport(
+ node.start,
+ node.start,
+ node.end,
+ node.source.value as string,
+ )
  if (node.exported) {
- defineExport(node.start, node.exported.name, `${importId}`)
+ defineExport(node.end, node.exported.name, `${importId}`)
  } else {
- s.appendLeft(node.start, `${ssrExportAllKey}(${importId});\n`)
+ s.appendLeft(node.end, `${ssrExportAllKey}(${importId});\n`)
  }
  }
  }