feat: expose getCombinedSourcemap in webpack, rspack and farm

src/farm/index.ts

@@ -17,7 +17,7 @@ import type {
 } from '../types'
 import type { WatchChangeEvents } from './utils'
 import path from 'path'
-import { toArray } from '../utils'
+import { getCombinedSourcemap, toArray } from '../utils'
 import { createFarmContext, unpluginContext } from './context'
 
 import {
@@ -187,7 +187,9 @@ export function toFarmPlugin(plugin: UnpluginOptions, options?: Record<string, a
           && plugin.transformInclude(params.resolvedPath)
         const farmContext = createFarmContext(context, params.resolvedPath)
         const resource: TransformResult = await _transform.call(
-          Object.assign(unpluginContext(context), farmContext),
+          Object.assign({
+            getCombinedSourcemap: () => getCombinedSourcemap(params.sourceMapChain, params.resolvedPath, params.content),
+          }, unpluginContext(context), farmContext),
           params.content,
           params.resolvedPath,
         )

src/rspack/loaders/transform.ts

@@ -26,7 +26,9 @@ export default async function transform(
   const context = createContext(this)
   const res = await plugin.transform.call(
     Object.assign(
-      {},
+      {
+        getCombinedSourcemap: () => map,
+      },
       this._compilation && createBuildContext(this._compiler, this._compilation, this),
       context,
     ),

src/utils.ts

@@ -1,5 +1,8 @@
+import type { DecodedSourceMap, RawSourceMap } from '@ampproject/remapping'
+import type { SourceMap } from 'rollup'
 import type { ResolvedUnpluginOptions } from './types'
 import { isAbsolute, normalize } from 'path'
+import remapping from '@ampproject/remapping'
 
 /**
  * Normalizes a given path when it's absolute. Normalizing means returning a new path by converting
@@ -72,3 +75,149 @@ export function resolveQuery(query: string | { unpluginName: string }) {
     return query.unpluginName
   }
 }
+
+const postfixRE = /[?#].*$/
+export function cleanUrl(url: string): string {
+  return url.replace(postfixRE, '')
+}
+
+/*
+  The following functions are copied from vite
+  https://github.com/vitejs/vite/blob/0fe95d4a71930cf55acd628efef59e6eae0f77f7/packages/vite/src/node/utils.ts#L781-L868
+
+  MIT License
+  Copyright (c) 2019-present, VoidZero Inc. and Vite contributors
+  https://github.com/vitejs/vite/blob/main/LICENSE
+*/
+const windowsDriveRE = /^[A-Z]:/
+const replaceWindowsDriveRE = /^([A-Z]):\//
+const linuxAbsolutePathRE = /^\/[^/]/
+function escapeToLinuxLikePath(path: string) {
+  if (windowsDriveRE.test(path)) {
+    return path.replace(replaceWindowsDriveRE, '/windows/$1/')
+  }
+  if (linuxAbsolutePathRE.test(path)) {
+    return `/linux${path}`
+  }
+  return path
+}
+
+const revertWindowsDriveRE = /^\/windows\/([A-Z])\//
+function unescapeToLinuxLikePath(path: string) {
+  if (path.startsWith('/linux/')) {
+    return path.slice('/linux'.length)
+  }
+  if (path.startsWith('/windows/')) {
+    return path.replace(revertWindowsDriveRE, '$1:/')
+  }
+  return path
+}
+
+const nullSourceMap: RawSourceMap = {
+  names: [],
+  sources: [],
+  mappings: '',
+  version: 3,
+}
+function combineSourcemaps(
+  filename: string,
+  sourcemapList: Array<DecodedSourceMap | RawSourceMap>,
+): RawSourceMap {
+  if (
+    sourcemapList.length === 0
+    || sourcemapList.every(m => m.sources.length === 0)
+  ) {
+    return { ...nullSourceMap }
+  }
+
+  // hack for parse broken with normalized absolute paths on windows (C:/path/to/something).
+  // escape them to linux like paths
+  // also avoid mutation here to prevent breaking plugin's using cache to generate sourcemaps like vue (see #7442)
+  sourcemapList = sourcemapList.map((sourcemap) => {
+    const newSourcemaps = { ...sourcemap }
+    newSourcemaps.sources = sourcemap.sources.map(source =>
+      source ? escapeToLinuxLikePath(source) : null,
+    )
+    if (sourcemap.sourceRoot) {
+      newSourcemaps.sourceRoot = escapeToLinuxLikePath(sourcemap.sourceRoot)
+    }
+    return newSourcemaps
+  })
+
+  // We don't declare type here so we can convert/fake/map as RawSourceMap
+  let map // : SourceMap
+  let mapIndex = 1
+  const useArrayInterface
+    = sourcemapList.slice(0, -1).find(m => m.sources.length !== 1) === undefined
+  if (useArrayInterface) {
+    map = remapping(sourcemapList, () => null)
+  }
+  else {
+    map = remapping(sourcemapList[0], (sourcefile) => {
+      const mapForSources = sourcemapList
+        .slice(mapIndex)
+        .find(s => s.sources.includes(sourcefile))
+
+      if (mapForSources) {
+        mapIndex++
+        return mapForSources
+      }
+      return null
+    })
+  }
+  if (!map.file) {
+    delete map.file
+  }
+
+  // unescape the previous hack
+  map.sources = map.sources.map(source =>
+    source ? unescapeToLinuxLikePath(source) : source,
+  )
+  map.file = filename
+
+  return map as RawSourceMap
+}
+
+export function getCombinedSourcemap(sourcemapChain: Nullable<Arrayable<SourceMap | string>>, filename: string, originalCode: string): SourceMap | null {
+  sourcemapChain = toArray(sourcemapChain)
+  let combinedMap = null
+
+  for (let m of sourcemapChain) {
+    if (typeof m === 'string')
+      m = JSON.parse(m)
+    if (!('version' in (m as SourceMap))) {
+      // { mappings: '' }
+      if ((m as SourceMap).mappings === '') {
+        combinedMap = { mappings: '' }
+        break
+      }
+      // empty, nullified source map
+      combinedMap = null
+      break
+    }
+    if (!combinedMap) {
+      const sm = m as SourceMap
+      // sourcemap should not include `sources: [null]` (because `sources` should be string) nor
+      // `sources: ['']` (because `''` means the path of sourcemap)
+      // but MagicString generates this when `filename` option is not set.
+      // Rollup supports these and therefore we support this as well
+      if (sm.sources.length === 1 && !sm.sources[0]) {
+        combinedMap = {
+          ...sm,
+          sources: [filename],
+          sourcesContent: [originalCode],
+        }
+      }
+      else {
+        combinedMap = sm
+      }
+    }
+    else {
+      combinedMap = combineSourcemaps(cleanUrl(filename), [
+        m as RawSourceMap,
+        combinedMap as RawSourceMap,
+      ]) as SourceMap
+    }
+  }
+  return combinedMap as SourceMap
+}

src/webpack/loaders/transform.ts

@@ -13,14 +13,20 @@ export default async function transform(this: LoaderContext<{ unpluginName: stri
 
   const context = createContext(this)
   const res = await plugin.transform.call(
-    Object.assign({}, createBuildContext({
-      addWatchFile: (file) => {
-        this.addDependency(file)
+    Object.assign(
+      {
+        getCombinedSourcemap: () => map,
       },
-      getWatchFiles: () => {
-        return this.getDependencies()
-      },
-    }, this._compiler!, this._compilation, this), context),
+      createBuildContext({
+        addWatchFile: (file) => {
+          this.addDependency(file)
+        },
+        getWatchFiles: () => {
+          return this.getDependencies()
+        },
+      }, this._compiler!, this._compilation, this),
+      context,
+    ),
     source,
     this.resource,
   )