feat(@parcel/transformer-js): Rewrite __dirname/__filename to be relative to asset.filePath

packages/core/core/src/resolveOptions.js

@@ -50,13 +50,24 @@ export default async function resolveOptions(
   }
 
   let entryRoot = getRootDir(entries);
+  /*
   let projectRootFile =
     (await resolveConfig(
       inputFS,
       path.join(entryRoot, 'index'),
       [...LOCK_FILE_NAMES, '.git', '.hg'],
       path.parse(entryRoot).root,
     )) || path.join(inputCwd, 'index'); // ? Should this just be rootDir
+  */
+
+  let projectRootFile =
+    path.join(inputCwd, 'index') ||
+    (await resolveConfig(
+      inputFS,
+      path.join(entryRoot, 'index'),
+      [...LOCK_FILE_NAMES, '.git', '.hg'],
+      path.parse(entryRoot).root,
+    )); // ? Should this just be rootDir
 
   let projectRoot = path.dirname(projectRootFile);
 

packages/examples/dirname/package.json

@@ -0,0 +1,23 @@
+{
+  "name": "@parcel/dirname",
+  "version": "2.2.1",
+  "license": "MIT",
+  "private": true,
+  "scripts": {
+    "build": "PARCEL_WORKERS=0 parcel build src/index.ts --no-source-maps --no-cache --no-optimize",
+    "clean-demo": "rm -rf .parcel-cache dist"
+  },
+  "devDependencies": {
+    "@parcel/babel-register": "^2.2.1",
+    "@parcel/core": "^2.2.1"
+  },
+  "@parcel/transformer-js": {
+    "relativeContext": true
+  },
+  "main": "dist/index.js",
+  "dependencies": {
+    "lodash": "^4.17.11",
+    "react": "^17.0.2",
+    "react-dom": "^17.0.2"
+  }
+}

packages/examples/dirname/src/index.ts

@@ -0,0 +1,21 @@
+type Config = {
+  plugins: {
+    resolve: string
+    options: {
+      [key: string]: string
+    }
+  }[]
+}
+
+const config: Config = {
+  plugins: [
+    {
+      resolve: `name`,
+      options: {
+        path: `${__dirname}/data`
+      }
+    }
+  ]
+}
+
+export default config

packages/transformers/js/core/src/global_replacer.rs

@@ -20,6 +20,7 @@ pub struct GlobalReplacer<'a> {
   pub decls: &'a mut HashSet<(JsWord, SyntaxContext)>,
   pub global_mark: swc_common::Mark,
   pub scope_hoist: bool,
+  pub relative_context: bool,
 }
 
 impl<'a> Fold for GlobalReplacer<'a> {
@@ -136,27 +137,61 @@ impl<'a> Fold for GlobalReplacer<'a> {
         }
         "__dirname" => {
           let dirname = if let Some(dirname) = self.filename.parent() {
-            if let Some(relative) = pathdiff::diff_paths(dirname, self.project_root) {
-              relative.to_slash_lossy()
+            if self.relative_context {
+              if let Some(relative) = pathdiff::diff_paths(self.project_root, dirname) {
+                relative.to_slash_lossy()
+              } else {
+                String::from("/")
+              }
             } else {
-              String::from("/")
+              if let Some(relative) = pathdiff::diff_paths(dirname, self.project_root) {
+                relative.to_slash_lossy()
+              } else {
+                String::from("/")
+              }
             }
           } else {
             String::from("/")
           };
 
+          let ce = ast::CallExpr {
+            span: DUMMY_SP,
+            type_args: None,
+            args: vec![
+              ast::ExprOrSpread {
+                spread: None,
+                expr: Box::new(ast::Expr::Ident(ast::Ident {
+                  optional: false,
+                  span: DUMMY_SP,
+                  sym: swc_atoms::JsWord::from("__dirname"),
+                })),
+              },
+              ast::ExprOrSpread {
+                spread: None,
+                expr: Box::new(ast::Expr::Lit(ast::Lit::Str(ast::Str {
+                  has_escape: false,
+                  span: DUMMY_SP,
+                  kind: ast::StrKind::Synthesized,
+                  value: swc_atoms::JsWord::from(dirname),
+                }))),
+              },
+            ],
+            callee: ast::ExprOrSuper::Expr(Box::new(ast::Expr::Member(ast::MemberExpr {
+              span: DUMMY_SP,
+              computed: false,
+              obj: ast::ExprOrSuper::Expr(Box::new(ast::Expr::Ident(ast::Ident::new(
+                "path".into(),
+                DUMMY_SP,
+              )))),
+              prop: Box::new(ast::Expr::Ident(ast::Ident::new("join".into(), DUMMY_SP))),
+            }))),
+          };
+
+          let pathjoin = ast::Expr::Call(ce);
+
           self.globals.insert(
             id.sym.clone(),
-            create_decl_stmt(
-              id.sym.clone(),
-              self.global_mark,
-              ast::Expr::Lit(ast::Lit::Str(ast::Str {
-                span: DUMMY_SP,
-                value: swc_atoms::JsWord::from(dirname),
-                has_escape: false,
-                kind: ast::StrKind::Synthesized,
-              })),
-            ),
+            create_decl_stmt(id.sym.clone(), self.global_mark, pathjoin),
           );
 
           self.decls.insert(id.to_id());

packages/transformers/js/core/src/lib.rs

@@ -66,6 +66,7 @@ pub struct Config {
   env: HashMap<swc_atoms::JsWord, swc_atoms::JsWord>,
   inline_fs: bool,
   insert_node_globals: bool,
+  relative_context: bool,
   is_browser: bool,
   is_worker: bool,
   is_type_script: bool,
@@ -367,7 +368,8 @@ pub fn transform(config: Config) -> Result<TransformResult, std::io::Error> {
                     filename: Path::new(&config.filename),
                     decls: &mut decls,
                     global_mark,
-                    scope_hoist: config.scope_hoist
+                    scope_hoist: config.scope_hoist,
+                    relative_context: config.relative_context
                   },
                   config.insert_node_globals && config.source_type != SourceType::Script
                 ),

packages/transformers/js/src/JSTransformer.js

@@ -85,6 +85,9 @@ const CONFIG_SCHEMA: SchemaEntity = {
     inlineFS: {
       type: 'boolean',
     },
+    relativeContext: {
+      type: 'boolean',
+    },
     inlineEnvironment: {
       oneOf: [
         {
@@ -106,6 +109,7 @@ type PackageJSONConfig = {|
   '@parcel/transformer-js'?: {|
     inlineFS?: boolean,
     inlineEnvironment?: boolean | Array<string>,
+    relativeContext?: boolean,
   |},
 |};
 
@@ -248,6 +252,8 @@ export default (new Transformer({
     let rootPkg = result?.contents;
 
     let inlineEnvironment = config.isSource;
+    const relativeContext =
+      pkg['@parcel/transformer-js']?.relativeContext ?? false;
     let inlineFS = !ignoreFS;
     if (result && rootPkg?.['@parcel/transformer-js']) {
       validateSchema.diagnostic(
@@ -280,6 +286,7 @@ export default (new Transformer({
       inlineFS,
       reactRefresh,
       decorators,
+      relativeContext,
     };
   },
   async transform({asset, config, options, logger}) {
@@ -392,6 +399,7 @@ export default (new Transformer({
       replace_env: !asset.env.isNode(),
       inline_fs: Boolean(config?.inlineFS) && !asset.env.isNode(),
       insert_node_globals: !asset.env.isNode(),
+      relative_context: Boolean(config?.relativeContext),
       is_browser: asset.env.isBrowser(),
       is_worker: asset.env.isWorker(),
       env,