Collect packages are used and eliminated in getServerSideProps

examples/ssr-caching/pages/index.js

@@ -1,3 +1,5 @@
+import React from 'react'
+
 export default function Index({ time }) {
   return (
     <main>
@@ -12,6 +14,7 @@ export async function getServerSideProps({ req, res }) {
     'Cache-Control',
     'public, s-maxage=10, stale-while-revalidate=59'
   )
+  res.setHeader('x-react-version', React.version)
 
   return {
     props: {

packages/next-swc/crates/core/src/lib.rs

@@ -31,6 +31,7 @@ DEALINGS IN THE SOFTWARE.
 
 use auto_cjs::contains_cjs;
 use either::Either;
+use fxhash::FxHashSet;
 use serde::Deserialize;
 use std::cell::RefCell;
 use std::rc::Rc;
@@ -109,6 +110,7 @@ pub fn custom_before_pass<'a, C: Comments + 'a>(
     file: Arc<SourceFile>,
     opts: &'a TransformOptions,
     comments: C,
+    eliminated_packages: Rc<RefCell<FxHashSet<String>>>,
 ) -> impl Fold + 'a {
     #[cfg(target_arch = "wasm32")]
     let relay_plugin = noop();
@@ -144,7 +146,10 @@ pub fn custom_before_pass<'a, C: Comments + 'a>(
                 Either::Right(noop())
             }
         },
-        Optional::new(next_ssg::next_ssg(), !opts.disable_next_ssg),
+        Optional::new(
+            next_ssg::next_ssg(eliminated_packages),
+            !opts.disable_next_ssg
+        ),
         amp_attributes::amp_attributes(),
         next_dynamic::next_dynamic(
             opts.is_development,

packages/next-swc/crates/core/src/next_ssg.rs

@@ -1,6 +1,8 @@
 use easy_error::{bail, Error};
 use fxhash::FxHashSet;
+use std::cell::RefCell;
 use std::mem::take;
+use std::rc::Rc;
 use swc_common::pass::{Repeat, Repeated};
 use swc_common::DUMMY_SP;
 use swc_ecmascript::ast::*;
@@ -12,9 +14,12 @@ use swc_ecmascript::{
 };
 
 /// Note: This paths requires running `resolver` **before** running this.
-pub fn next_ssg() -> impl Fold {
+pub fn next_ssg(eliminated_packages: Rc<RefCell<FxHashSet<String>>>) -> impl Fold {
     Repeat::new(NextSsg {
-        state: Default::default(),
+        state: State {
+            eliminated_packages,
+            ..Default::default()
+        },
         in_lhs_of_var: false,
     })
 }
@@ -41,6 +46,10 @@ struct State {
     done: bool,
 
     should_run_again: bool,
+
+    /// Track the import packages which are eliminated in the
+    /// `getServerSideProps`
+    pub eliminated_packages: Rc<RefCell<FxHashSet<String>>>,
 }
 
 impl State {
@@ -288,7 +297,7 @@ impl Fold for Analyzer<'_> {
 
 /// Actual implementation of the transform.
 struct NextSsg {
-    state: State,
+    pub state: State,
     in_lhs_of_var: bool,
 }
 
@@ -349,6 +358,12 @@ impl Fold for NextSsg {
             | ImportSpecifier::Default(ImportDefaultSpecifier { local, .. })
             | ImportSpecifier::Namespace(ImportStarAsSpecifier { local, .. }) => {
                 if self.should_remove(local.to_id()) {
+                    if self.state.is_server_props {
+                        self.state
+                            .eliminated_packages
+                            .borrow_mut()
+                            .insert(local.sym.to_string());
+                    }
                     tracing::trace!(
                         "Dropping import `{}{:?}` because it should be removed",
                         local.sym,

packages/next-swc/crates/core/tests/errors.rs

@@ -63,5 +63,10 @@ fn styled_jsx_errors(input: PathBuf) {
 #[fixture("tests/errors/next-ssg/**/input.js")]
 fn next_ssg_errors(input: PathBuf) {
     let output = input.parent().unwrap().join("output.js");
-    test_fixture_allowing_error(syntax(), &|_tr| next_ssg(), &input, &output);
+    test_fixture_allowing_error(
+        syntax(),
+        &|_tr| next_ssg(Default::default()),
+        &input,
+        &output,
+    );
 }

packages/next-swc/crates/core/tests/fixture.rs

@@ -112,7 +112,7 @@ fn next_ssg_fixture(input: PathBuf) {
                 },
                 top_level_mark,
             );
-            chain!(next_ssg(), jsx)
+            chain!(next_ssg(Default::default()), jsx)
         },
         &input,
         &output,

packages/next-swc/crates/core/tests/full.rs

@@ -72,7 +72,13 @@ fn test(input: &Path, minify: bool) {
                 &handler,
                 &options.swc,
                 |_, comments| {
-                    custom_before_pass(cm.clone(), fm.clone(), &options, comments.clone())
+                    custom_before_pass(
+                        cm.clone(),
+                        fm.clone(),
+                        &options,
+                        comments.clone(),
+                        Default::default(),
+                    )
                 },
                 |_, _| noop(),
             ) {

packages/next-swc/crates/napi/src/bundle/mod.rs

@@ -121,7 +121,7 @@ impl Task for BundleTask {
     }
 
     fn resolve(self, env: napi::Env, output: Self::Output) -> napi::Result<Self::JsValue> {
-        complete_output(&env, output)
+        complete_output(&env, output, Default::default())
     }
 }
 

packages/next-swc/crates/napi/src/lib.rs

@@ -35,6 +35,7 @@ extern crate napi_derive;
 extern crate swc_node_base;
 
 use backtrace::Backtrace;
+use fxhash::FxHashSet;
 use napi::{CallContext, Env, JsObject, JsUndefined};
 use std::{env, panic::set_hook, sync::Arc};
 use swc::{Compiler, TransformOutput};
@@ -84,8 +85,25 @@ fn construct_compiler(ctx: CallContext) -> napi::Result<JsUndefined> {
     ctx.env.get_undefined()
 }
 
-pub fn complete_output(env: &Env, output: TransformOutput) -> napi::Result<JsObject> {
-    env.to_js_value(&output)?.coerce_to_object()
+pub fn complete_output(
+    env: &Env,
+    output: TransformOutput,
+    eliminated_packages: FxHashSet<String>,
+) -> napi::Result<JsObject> {
+    let mut js_output = env.create_object()?;
+    js_output.set_named_property("code", env.create_string_from_std(output.code)?)?;
+    if let Some(map) = output.map {
+        js_output.set_named_property("map", env.create_string_from_std(map)?)?;
+    }
+    if !eliminated_packages.is_empty() {
+        js_output.set_named_property(
+            "eliminatedPackages",
+            env.create_string_from_std(serde_json::to_string(
+                &eliminated_packages.into_iter().collect::<Vec<String>>(),
+            )?)?,
+        )?;
+    }
+    Ok(js_output)
 }
 
 pub type ArcCompiler = Arc<Compiler>;

packages/next-swc/crates/napi/src/minify.rs

@@ -85,7 +85,7 @@ impl Task for MinifyTask {
     }
 
     fn resolve(self, env: napi::Env, output: Self::Output) -> napi::Result<Self::JsValue> {
-        complete_output(&env, output)
+        complete_output(&env, output, Default::default())
     }
 }
 
@@ -113,5 +113,5 @@ pub fn minify_sync(cx: CallContext) -> napi::Result<JsObject> {
     let output = try_with_handler(c.cm.clone(), true, |handler| c.minify(fm, handler, &opts))
         .convert_err()?;
 
-    complete_output(cx.env, output)
+    complete_output(cx.env, output, Default::default())
 }

packages/next-swc/crates/napi/src/transform.rs

@@ -31,12 +31,15 @@ use crate::{
     util::{deserialize_json, CtxtExt, MapErr},
 };
 use anyhow::{anyhow, bail, Context as _, Error};
+use fxhash::FxHashSet;
 use napi::{CallContext, Env, JsBoolean, JsBuffer, JsObject, JsString, JsUnknown, Status, Task};
 use next_swc::{custom_before_pass, TransformOptions};
 use std::fs::read_to_string;
 use std::{
+    cell::RefCell,
     convert::TryFrom,
     panic::{catch_unwind, AssertUnwindSafe},
+    rc::Rc,
     sync::Arc,
 };
 use swc::{try_with_handler, Compiler, TransformOutput};
@@ -60,10 +63,11 @@ pub struct TransformTask {
 }
 
 impl Task for TransformTask {
-    type Output = TransformOutput;
+    type Output = (TransformOutput, FxHashSet<String>);
     type JsValue = JsObject;
 
     fn compute(&mut self) -> napi::Result<Self::Output> {
+        let eliminated_packages: Rc<RefCell<fxhash::FxHashSet<String>>> = Default::default();
         let res = catch_unwind(AssertUnwindSafe(|| {
             try_with_handler(self.c.cm.clone(), true, |handler| {
                 self.c.run(|| {
@@ -102,7 +106,15 @@ impl Task for TransformTask {
                         None,
                         handler,
                         &options.swc,
-                        |_, comments| custom_before_pass(cm, file, &options, comments.clone()),
+                        |_, comments| {
+                            custom_before_pass(
+                                cm,
+                                file,
+                                &options,
+                                comments.clone(),
+                                eliminated_packages.clone(),
+                            )
+                        },
                         |_, _| noop(),
                     )
                 })
@@ -117,16 +129,22 @@ impl Task for TransformTask {
         });
 
         match res {
-            Ok(res) => res.convert_err(),
+            Ok(res) => res
+                .map(|o| (o, eliminated_packages.replace(Default::default())))
+                .convert_err(),
             Err(err) => Err(napi::Error::new(
                 Status::GenericFailure,
                 format!("{:?}", err),
             )),
         }
     }
 
-    fn resolve(self, env: Env, result: Self::Output) -> napi::Result<Self::JsValue> {
-        complete_output(&env, result)
+    fn resolve(
+        self,
+        env: Env,
+        (output, eliminated_packages): Self::Output,
+    ) -> napi::Result<Self::JsValue> {
+        complete_output(&env, output, eliminated_packages)
     }
 }
 
@@ -189,7 +207,7 @@ where
     })
     .convert_err()?;
 
-    complete_output(cx.env, output)
+    complete_output(cx.env, output, Default::default())
 }
 
 #[js_function(4)]

packages/next-swc/crates/wasm/src/lib.rs

@@ -55,7 +55,9 @@ pub fn transform_sync(s: &str, opts: JsValue) -> Result<JsValue, JsValue> {
                 None,
                 handler,
                 &opts.swc,
-                |_, comments| custom_before_pass(cm, file, &opts, comments.clone()),
+                |_, comments| {
+                    custom_before_pass(cm, file, &opts, comments.clone(), Default::default())
+                },
                 |_, _| noop(),
             )
             .context("failed to process js file")?;

packages/next/build/webpack/loaders/next-swc-loader.js

@@ -88,7 +88,13 @@ async function loaderTransform(parentTrace, source, inputSourceMap) {
   const swcSpan = parentTrace.traceChild('next-swc-transform')
   return swcSpan.traceAsyncFn(() =>
     transform(source, programmaticOptions).then((output) => {
-      return [output.code, output.map ? JSON.parse(output.map) : undefined]
+      return [
+        output.code,
+        output.map ? JSON.parse(output.map) : undefined,
+        output.eliminatedPackages
+          ? JSON.parse(output.eliminatedPackages)
+          : undefined,
+      ]
     })
   )
 }
@@ -123,13 +129,17 @@ export function pitch() {
 
 export default function swcLoader(inputSource, inputSourceMap) {
   const loaderSpan = this.currentTraceSpan.traceChild('next-swc-loader')
+  const globalEliminatedPackages = this.eliminatedPackages
   const callback = this.async()
   loaderSpan
     .traceAsyncFn(() =>
       loaderTransform.call(this, loaderSpan, inputSource, inputSourceMap)
     )
     .then(
-      ([transformedSource, outputSourceMap]) => {
+      ([transformedSource, outputSourceMap, eliminatedPackages]) => {
+        if (eliminatedPackages) {
+          globalEliminatedPackages.push(...eliminatedPackages)
+        }
         callback(null, transformedSource, outputSourceMap || inputSourceMap)
       },
       (err) => {

packages/next/build/webpack/plugins/telemetry-plugin.ts

@@ -1,4 +1,7 @@
-import type { webpack5 as webpack } from 'next/dist/compiled/webpack/webpack'
+import {
+  NormalModule,
+  webpack5 as webpack,
+} from 'next/dist/compiled/webpack/webpack'
 
 type Feature =
   | 'next/image'
@@ -54,6 +57,8 @@ const BUILD_FEATURES: Array<Feature> = [
   'swcEmotion',
 ]
 
+const ELIMINATED_PACKAGES: string[] = []
+
 /**
  * Plugin that queries the ModuleGraph to look for modules that correspond to
  * certain features (e.g. next/image and next/script) and record how many times
@@ -83,6 +88,9 @@ export class TelemetryPlugin implements webpack.WebpackPluginInstance {
     compiler.hooks.make.tapAsync(
       TelemetryPlugin.name,
       async (compilation: webpack.Compilation, callback: () => void) => {
+        compilation.hooks.afterCodeGeneration.tap(TelemetryPlugin.name, () => {
+          console.log(compilation.assets)
+        })
         compilation.hooks.finishModules.tapAsync(
           TelemetryPlugin.name,
           async (modules: Iterable<Module>, modulesFinish: () => void) => {
@@ -105,11 +113,23 @@ export class TelemetryPlugin implements webpack.WebpackPluginInstance {
         callback()
       }
     )
+    compiler.hooks.compilation.tap(TelemetryPlugin.name, (compilation) => {
+      const moduleHooks = NormalModule.getCompilationHooks(compilation)
+      moduleHooks.loader.tap(TelemetryPlugin.name, (loaderContext: any) => {
+        loaderContext.eliminatedPackages = ELIMINATED_PACKAGES
+      })
+    })
   }
 
   usages(): FeatureUsage[] {
     return [...this.usageTracker.values()]
   }
+
+  packagesUsedInServerSideProps(): { package: string }[] {
+    return Array.from(new Set(ELIMINATED_PACKAGES)).map((pkg) => ({
+      package: pkg,
+    }))
+  }
 }
 
 /**