fix(es/parser): Parse export default from; with exportDefaultFrom: true option (#10373)

magic-akari · web-flow · commit a270cb0f469b · 2025-04-15T12:18:06.000+09:00
**Related issue:** - Closes #10372
diff --git a/.changeset/weak-coins-cheat.md b/.changeset/weak-coins-cheat.md
@@ -0,0 +1,6 @@
+---
+swc_ecma_parser: patch
+swc_core: patch
+---
+
+fix(es/parser): Parse `export default from;` with `exportDefaultFrom: true` option
diff --git a/crates/swc_ecma_parser/src/parser/macros.rs b/crates/swc_ecma_parser/src/parser/macros.rs
@@ -111,6 +111,13 @@ macro_rules! peeked_is {
         }
     }};
 
+    ($p:expr, Str) => {{
+        match peek!($p) {
+            Some(&Token::Str { .. }) => true,
+            _ => false,
+        }
+    }};
+
     ($p:expr, ';') => {{
         compile_error!("peeked_is!(self, ';') is invalid");
     }};
diff --git a/crates/swc_ecma_parser/src/parser/stmt/module_item.rs b/crates/swc_ecma_parser/src/parser/stmt/module_item.rs
@@ -491,7 +491,7 @@ impl<I: Tokens> Parser<I> {
                 let decl = self.parse_default_fn(start, decorators)?;
                 return Ok(decl.into());
             } else if self.input.syntax().export_default_from()
-                && (is!(self, "from")
+                && ((is!(self, "from") && peeked_is!(self, Str))
                     || (is!(self, ',') && (peeked_is!(self, '{') || peeked_is!(self, '*'))))
             {
                 export_default = Some(Ident::new_no_ctxt("default".into(), self.input.prev_span()))
diff --git a/crates/swc_ecma_parser/tests/js.rs b/crates/swc_ecma_parser/tests/js.rs
@@ -23,10 +23,11 @@ fn spec(file: PathBuf) {
         "{}.json",
         file.file_name().unwrap().to_string_lossy()
     ));
-    run_spec(&file, &output);
+    let config_path = file.parent().unwrap().join("config.json");
+    run_spec(&file, &output, &config_path);
 }
 
-fn run_spec(file: &Path, output_json: &Path) {
+fn run_spec(file: &Path, output_json: &Path, config_path: &Path) {
     let file_name = file
         .display()
         .to_string()
@@ -50,7 +51,7 @@ fn run_spec(file: &Path, output_json: &Path) {
         );
     }
 
-    with_parser(false, file, false, |p, _| {
+    with_parser(false, file, false, config_path, |p, _| {
         let program = p.parse_program()?.fold_with(&mut Normalizer {
             drop_span: false,
             is_test262: false,
@@ -73,6 +74,7 @@ fn with_parser<F, Ret>(
     treat_error_as_bug: bool,
     file_name: &Path,
     shift: bool,
+    config_path: &Path,
     f: F,
 ) -> Result<Ret, StdErr>
 where
@@ -89,17 +91,30 @@ where
             .load_file(file_name)
             .unwrap_or_else(|e| panic!("failed to load {}: {}", file_name.display(), e));
 
-        let lexer = Lexer::new(
+        // Try to load EsSyntax configuration from config.json in the same directory as
+        // the test file
+        let syntax = {
+            let mut config_str = String::new();
+            File::open(config_path)
+                .ok()
+                .and_then(|mut file| file.read_to_string(&mut config_str).ok())
+                .and_then(|_| serde_json::from_str::<EsSyntax>(&config_str).ok())
+        }
+        .map(Syntax::Es)
+        .unwrap_or_else(|| {
+            eprintln!(
+                "Failed to load or parse {}, using default configuration",
+                config_path.display()
+            );
             Syntax::Es(EsSyntax {
                 explicit_resource_management: true,
                 import_attributes: true,
                 decorators: true,
                 ..Default::default()
-            }),
-            EsVersion::Es2015,
-            (&*fm).into(),
-            Some(&comments),
-        );
+            })
+        });
+
+        let lexer = Lexer::new(syntax, EsVersion::Es2015, (&*fm).into(), Some(&comments));
 
         let mut p = Parser::new_from(lexer);
 
diff --git a/crates/swc_ecma_parser/tests/js/issue-10372/config.json b/crates/swc_ecma_parser/tests/js/issue-10372/config.json
@@ -0,0 +1,5 @@
+{
+    "syntax": "ecmascript",
+    "exportDefaultFrom": true,
+    "jsx": false
+}
diff --git a/crates/swc_ecma_parser/tests/js/issue-10372/input.js b/crates/swc_ecma_parser/tests/js/issue-10372/input.js
@@ -0,0 +1,2 @@
+const from = {};
+export default from;
diff --git a/crates/swc_ecma_parser/tests/js/issue-10372/input.js.json b/crates/swc_ecma_parser/tests/js/issue-10372/input.js.json
@@ -0,0 +1,66 @@
+{
+  "type": "Module",
+  "span": {
+    "start": 1,
+    "end": 38
+  },
+  "body": [
+    {
+      "type": "VariableDeclaration",
+      "span": {
+        "start": 1,
+        "end": 17
+      },
+      "ctxt": 0,
+      "kind": "const",
+      "declare": false,
+      "declarations": [
+        {
+          "type": "VariableDeclarator",
+          "span": {
+            "start": 7,
+            "end": 16
+          },
+          "id": {
+            "type": "Identifier",
+            "span": {
+              "start": 7,
+              "end": 11
+            },
+            "ctxt": 0,
+            "value": "from",
+            "optional": false,
+            "typeAnnotation": null
+          },
+          "init": {
+            "type": "ObjectExpression",
+            "span": {
+              "start": 14,
+              "end": 16
+            },
+            "properties": []
+          },
+          "definite": false
+        }
+      ]
+    },
+    {
+      "type": "ExportDefaultExpression",
+      "span": {
+        "start": 18,
+        "end": 38
+      },
+      "expression": {
+        "type": "Identifier",
+        "span": {
+          "start": 33,
+          "end": 37
+        },
+        "ctxt": 0,
+        "value": "from",
+        "optional": false
+      }
+    }
+  ],
+  "interpreter": null
+}

Original file line number	Diff line number	Diff line change
`@@ -491,7 +491,7 @@ impl<I: Tokens> Parser<I> {`
`491`	`491`	`let decl = self.parse_default_fn(start, decorators)?;`
`492`	`492`	`return Ok(decl.into());`
`493`	`493`	`} else if self.input.syntax().export_default_from()`
`494`		`- && (is!(self, "from")`
	`494`	`+ && ((is!(self, "from") && peeked_is!(self, Str))`
`495`	`495`	`\|\| (is!(self, ',') && (peeked_is!(self, '{') \|\| peeked_is!(self, '*'))))`
`496`	`496`	`{`
`497`	`497`	`export_default = Some(Ident::new_no_ctxt("default".into(), self.input.prev_span()))`
Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,2 @@`
	`1`	`+const from = {};`
	`2`	`+export default from;`