Add page config swc transform (#30183)

* Add page config swc transform

* Build next-swc binaries

* Disable page config transform in some scenarios

* Build next-swc binaries

* Only skip dropping bundle in dev mode

* Build next-swc binaries

* Allow for amp 'hybrid' configuration

* Build next-swc binaries

packages/next/build/swc/Cargo.lock

@@ -192,6 +192,7 @@ dependencies = [
  "libc",
  "num-integer",
  "num-traits",
+ "time",
  "winapi",
 ]
 
@@ -715,6 +716,7 @@ version = "0.0.0"
 dependencies = [
  "anyhow",
  "backtrace",
+ "chrono",
  "easy-error",
  "fxhash",
  "napi",
@@ -2308,6 +2310,16 @@ dependencies = [
  "once_cell",
 ]
 
+[[package]]
+name = "time"
+version = "0.1.43"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ca8a50ef2360fbd1eeb0ecd46795a87a19024eb4b53c5dc916ca1fd95fe62438"
+dependencies = [
+ "libc",
+ "winapi",
+]
+
 [[package]]
 name = "tinyvec"
 version = "1.5.0"

packages/next/build/swc/Cargo.toml

@@ -9,6 +9,7 @@ crate-type = ["cdylib", "rlib"]
 [dependencies]
 anyhow = "1.0"
 backtrace = "0.3"
+chrono = "0.4"
 easy-error = "1.0.0"
 napi = { version = "1", features = ["serde-json"] }
 napi-derive = "1"

packages/next/build/swc/src/lib.rs

@@ -47,6 +47,7 @@ pub mod hook_optimizer;
 pub mod minify;
 pub mod next_dynamic;
 pub mod next_ssg;
+pub mod page_config;
 pub mod styled_jsx;
 mod transform;
 mod util;
@@ -60,8 +61,14 @@ pub struct TransformOptions {
     #[serde(default)]
     pub disable_next_ssg: bool,
 
+    #[serde(default)]
+    pub disable_page_config: bool,
+
     #[serde(default)]
     pub pages_dir: Option<PathBuf>,
+
+    #[serde(default)]
+    pub is_development: bool,
 }
 
 pub fn custom_before_pass(name: &FileName, opts: &TransformOptions) -> impl Fold {
@@ -71,6 +78,10 @@ pub fn custom_before_pass(name: &FileName, opts: &TransformOptions) -> impl Fold
         Optional::new(next_ssg::next_ssg(), !opts.disable_next_ssg),
         amp_attributes::amp_attributes(),
         next_dynamic::next_dynamic(name.clone(), opts.pages_dir.clone()),
+        Optional::new(
+            page_config::page_config(opts.is_development),
+            !opts.disable_page_config
+        )
     )
 }
 

packages/next/build/swc/src/page_config.rs

@@ -0,0 +1,151 @@
+use chrono::Utc;
+use swc_common::{Span, DUMMY_SP};
+use swc_ecmascript::ast::*;
+use swc_ecmascript::utils::HANDLER;
+use swc_ecmascript::visit::{Fold, FoldWith};
+
+pub fn page_config(is_development: bool) -> impl Fold {
+  PageConfig {
+    is_development,
+    ..Default::default()
+  }
+}
+
+pub fn page_config_test() -> impl Fold {
+  PageConfig {
+    drop_bundle: false,
+    in_test: true,
+    is_development: false,
+  }
+}
+
+#[derive(Debug, Default)]
+struct PageConfig {
+  drop_bundle: bool,
+  in_test: bool,
+  is_development: bool,
+}
+
+fn handle_error(details: &str, span: Span) {
+  let message = format!("Invalid page config export found. {} \
+  See: https://nextjs.org/docs/messages/invalid-page-config", details);
+  HANDLER.with(|handler| handler.struct_span_err(span, &message).emit());
+}
+
+const STRING_LITERAL_DROP_BUNDLE: &str = "__NEXT_DROP_CLIENT_FILE__";
+const CONFIG_KEY: &str = "config";
+
+impl Fold for PageConfig {
+  fn fold_module_items(&mut self, items: Vec<ModuleItem>) -> Vec<ModuleItem> {
+    let mut new_items = vec![];
+    for item in items {
+      new_items.push(item.fold_with(self));
+      if !self.is_development && self.drop_bundle {
+        let timestamp = match self.in_test {
+          true => String::from("mock_timestamp"),
+          false => Utc::now().timestamp().to_string(),
+        };
+        return vec![ModuleItem::Stmt(Stmt::Decl(Decl::Var(VarDecl {
+          decls: vec![VarDeclarator {
+            name: Pat::Ident(BindingIdent {
+              id: Ident {
+                sym: STRING_LITERAL_DROP_BUNDLE.into(),
+                span: DUMMY_SP,
+                optional: false,
+              },
+              type_ann: None,
+            }),
+            init: Some(Box::new(Expr::Lit(Lit::Str(Str {
+              value: format!("{} {}", STRING_LITERAL_DROP_BUNDLE, timestamp).into(),
+              span: DUMMY_SP,
+              kind: StrKind::Synthesized {},
+              has_escape: false,
+            })))),
+            span: DUMMY_SP,
+            definite: false,
+          }],
+          span: DUMMY_SP,
+          kind: VarDeclKind::Const,
+          declare: false,
+        })))];
+      }
+    }
+
+    new_items
+  }
+
+  fn fold_export_decl(&mut self, export: ExportDecl) -> ExportDecl {
+    match &export.decl {
+      Decl::Var(var_decl) => {
+        for decl in &var_decl.decls {
+          let mut is_config = false;
+          if let Pat::Ident(ident) = &decl.name {
+            if &ident.id.sym == CONFIG_KEY {
+              is_config = true;
+            }
+          }
+
+          if is_config {
+            if let Some(expr) = &decl.init {
+              if let Expr::Object(obj) = &**expr {
+                for prop in &obj.props {
+                  if let PropOrSpread::Prop(prop) = prop {
+                    if let Prop::KeyValue(kv) = &**prop {
+                      match &kv.key {
+                        PropName::Ident(ident) => {
+                          if &ident.sym == "amp" {
+                            if let Expr::Lit(Lit::Bool(Bool { value, .. })) = &*kv.value {
+                              if *value {
+                                self.drop_bundle = true;
+                              }
+                            } else if let Expr::Lit(Lit::Str(_)) = &*kv.value {
+                              // Do not replace bundle
+                            } else {
+                              handle_error("Invalid value found.", export.span);
+                            }
+                          }
+                        }
+                        _ => {
+                          handle_error("Invalid property found.", export.span);
+                        }
+                      }
+                    } else {
+                      handle_error("Invalid property or value.", export.span);
+                    }
+                  } else {
+                    handle_error("Property spread is not allowed.", export.span);
+                  }
+                }
+              } else {
+                handle_error("Expected config to be an object.", export.span);
+              }
+            } else {
+              handle_error("Expected config to be an object.", export.span);
+            }
+          }
+        }
+      }
+      _ => {}
+    }
+    export
+  }
+
+  fn fold_export_named_specifier(
+    &mut self,
+    specifier: ExportNamedSpecifier,
+  ) -> ExportNamedSpecifier {
+    match &specifier.exported {
+      Some(ident) => {
+        if &ident.sym == CONFIG_KEY {
+          handle_error("Config cannot be re-exported.", specifier.span)
+        }
+      }
+      None => {
+        if &specifier.orig.sym == CONFIG_KEY {
+          handle_error("Config cannot be re-exported.", specifier.span)
+        }
+      }
+    }
+    specifier
+  }
+}

packages/next/build/swc/tests/fixture.rs

@@ -1,6 +1,6 @@
 use next_swc::{
     amp_attributes::amp_attributes, next_dynamic::next_dynamic, next_ssg::next_ssg,
-    styled_jsx::styled_jsx,
+    page_config::page_config_test, styled_jsx::styled_jsx,
 };
 use std::path::PathBuf;
 use swc_common::{chain, comments::SingleThreadedComments, FileName, Mark, Span, DUMMY_SP};
@@ -113,3 +113,9 @@ fn styled_jsx_span_should_not_affect_hash(input: PathBuf) {
         &output,
     );
 }
+
+#[fixture("tests/fixture/page-config/**/input.js")]
+fn page_config_fixture(input: PathBuf) {
+    let output = input.parent().unwrap().join("output.js");
+    test_fixture(syntax(), &|_tr| page_config_test(), &input, &output);
+}

packages/next/build/swc/tests/fixture/page-config/amp-hybrid/input.js

@@ -0,0 +1,7 @@
+export const config = { amp: 'hybrid' }
+
+function About(props) {
+  return <h3>My AMP About Page!</h3>
+}
+
+export default About

packages/next/build/swc/tests/fixture/page-config/amp-hybrid/output.js

@@ -0,0 +1,7 @@
+export const config = {
+  amp: "hybrid"
+};
+function About(props) {
+  return <h3 >My AMP About Page!</h3>;
+}
+export default About;

packages/next/build/swc/tests/fixture/page-config/amp-true/input.js

@@ -0,0 +1,7 @@
+export const config = { amp: true }
+
+function About(props) {
+  return <h3>My AMP About Page!</h3>
+}
+
+export default About

packages/next/build/swc/tests/fixture/page-config/amp-true/output.js

@@ -0,0 +1 @@
+const __NEXT_DROP_CLIENT_FILE__ = "__NEXT_DROP_CLIENT_FILE__ mock_timestamp";

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

@@ -74,6 +74,8 @@ function getSWCOptions({
         : {}),
       // Disables getStaticProps/getServerSideProps tree shaking on the server compilation for pages
       disableNextSsg: true,
+      disablePageConfig: true,
+      isDevelopment: development,
       pagesDir,
       env: {
         targets: {
@@ -95,6 +97,7 @@ function getSWCOptions({
           }
         : {}),
       disableNextSsg: !isPageFile,
+      isDevelopment: development,
       pagesDir,
       jsc,
     }

test/integration/page-config/next.config.js

@@ -1,5 +0,0 @@
-module.exports = {
-  experimental: {
-    swcLoader: false,
-  },
-}