Revert "Fix tracing of server actions imported by client components (#78968) (#82161)

It seems these additional fs operations/transforms on client components
while tracing dependencies is causing a big perf hit which is not worth
the edge case of catching fs dependencies in server actions from client
components.

A workaround is available without our automatic tracing via
`outputFileTracingIncludes` so this reverts the tracing to alleviate the
perf concern.

We will be able to handle cases like this without the perf consequence
with turbopack going forward.

This reverts commit af0473b.

Closes: #81902

Author: ijjk

packages/next/src/build/webpack-config.ts

@@ -2015,7 +2015,6 @@ export default async function getBaseWebpackConfig(
             appDirEnabled: hasAppDir,
             traceIgnores: [],
             compilerType,
-            swcLoaderConfig: swcDefaultLoader,
           }
         ),
       // Moment.js is an extremely popular library that bundles large locale files

packages/next/src/build/webpack/plugins/next-trace-entrypoints-plugin.ts

@@ -18,10 +18,8 @@ import picomatch from 'next/dist/compiled/picomatch'
 import { getModuleBuildInfo } from '../loaders/get-module-build-info'
 import { getPageFilePath } from '../../entries'
 import { resolveExternal } from '../../handle-externals'
-import swcLoader, { type SWCLoaderOptions } from '../loaders/next-swc-loader'
 import { isMetadataRouteFile } from '../../../lib/metadata/is-metadata-route'
 import { getCompilationSpan } from '../utils'
-import { isClientComponentEntryModule } from '../loaders/utils'
 
 const PLUGIN_NAME = 'TraceEntryPointsPlugin'
 export const TRACE_IGNORES = [
@@ -139,10 +137,6 @@ export class TraceEntryPointsPlugin implements webpack.WebpackPluginInstance {
   private traceIgnores: string[]
   private esmExternals?: NextConfigComplete['experimental']['esmExternals']
   private compilerType: CompilerNameValues
-  private swcLoaderConfig: {
-    loader: string
-    options: Partial<SWCLoaderOptions>
-  }
 
   constructor({
     rootDir,
@@ -153,7 +147,6 @@ export class TraceEntryPointsPlugin implements webpack.WebpackPluginInstance {
     traceIgnores,
     esmExternals,
     outputFileTracingRoot,
-    swcLoaderConfig,
   }: {
     rootDir: string
     compilerType: CompilerNameValues
@@ -163,7 +156,6 @@ export class TraceEntryPointsPlugin implements webpack.WebpackPluginInstance {
     traceIgnores?: string[]
     outputFileTracingRoot?: string
     esmExternals?: NextConfigComplete['experimental']['esmExternals']
-    swcLoaderConfig: TraceEntryPointsPlugin['swcLoaderConfig']
   }) {
     this.rootDir = rootDir
     this.appDir = appDir
@@ -174,7 +166,6 @@ export class TraceEntryPointsPlugin implements webpack.WebpackPluginInstance {
     this.traceIgnores = traceIgnores || []
     this.tracingRoot = outputFileTracingRoot || rootDir
     this.compilerType = compilerType
-    this.swcLoaderConfig = swcLoaderConfig
   }
 
   // Here we output all traced assets and webpack chunks to a
@@ -409,18 +400,6 @@ export class TraceEntryPointsPlugin implements webpack.WebpackPluginInstance {
                 }
               })
 
-            const readOriginalSource = (path: string) => {
-              return new Promise<string | Buffer>((resolve) => {
-                compilation.inputFileSystem.readFile(path, (err, result) => {
-                  if (err) {
-                    // we can't throw here as that crashes build un-necessarily
-                    return resolve('')
-                  }
-                  resolve(result || '')
-                })
-              })
-            }
-
             const readFile = async (
               path: string
             ): Promise<Buffer | string | null> => {
@@ -429,60 +408,6 @@ export class TraceEntryPointsPlugin implements webpack.WebpackPluginInstance {
               // map the transpiled source when available to avoid
               // parse errors in node-file-trace
               let source: Buffer | string = mod?.originalSource?.()?.buffer()
-
-              try {
-                // fallback to reading raw source file, this may fail
-                // due to unsupported syntax but best effort attempt
-                let usingOriginalSource = false
-                if (!source || isClientComponentEntryModule(mod)) {
-                  source = await readOriginalSource(path)
-                  usingOriginalSource = true
-                }
-                const sourceString = source.toString()
-
-                // If this is a client component we need to trace the
-                // original transpiled source not the client proxy which is
-                // applied before this plugin is run due to the
-                // client-module-loader
-                if (
-                  usingOriginalSource &&
-                  // don't attempt transpiling CSS or image imports
-                  path.match(/\.(tsx|ts|js|cjs|mjs|jsx)$/)
-                ) {
-                  let transformResolve: (result: string) => void
-                  let transformReject: (error: unknown) => void
-                  const transformPromise = new Promise<string>(
-                    (resolve, reject) => {
-                      transformResolve = resolve
-                      transformReject = reject
-                    }
-                  )
-
-                  // TODO: should we apply all loaders except the
-                  // client-module-loader?
-                  swcLoader.apply(
-                    {
-                      resourcePath: path,
-                      getOptions: () => {
-                        return this.swcLoaderConfig.options
-                      },
-                      async: () => {
-                        return (err: unknown, result: string) => {
-                          if (err) {
-                            return transformReject(err)
-                          }
-                          return transformResolve(result)
-                        }
-                      },
-                    },
-                    [sourceString, undefined]
-                  )
-                  source = await transformPromise
-                }
-              } catch {
-                /* non-fatal */
-              }
-
               return source || ''
             }