From a4922ce5d26f1a4f939e9ed3c7737894f9ea38b3 Mon Sep 17 00:00:00 2001
From: Naveen Jain <nveenjain@gmail.com>
Date: Thu, 1 Feb 2018 19:37:20 +0530
Subject: [PATCH] [BugFix] Compile export default from

---
 packages/babylon/src/parser/statement.js      | 43 ++++++++++++++-----
 .../invalid-export-default/options.json       |  2 +-
 .../_no-plugin/export-default/options.json    |  2 +-
 3 files changed, 35 insertions(+), 12 deletions(-)

diff --git a/packages/babylon/src/parser/statement.js b/packages/babylon/src/parser/statement.js
index 39f112595de5..62ef5a1107b1 100644
--- a/packages/babylon/src/parser/statement.js
+++ b/packages/babylon/src/parser/statement.js
@@ -1310,21 +1310,44 @@ export default class StatementParser extends ExpressionParser {
       this.parseExportStar(node);
       if (node.type === "ExportAllDeclaration") return node;
     } else if (this.isExportDefaultSpecifier()) {
-      this.expectPlugin("exportDefaultFrom");
       const specifier = this.startNode();
       specifier.exported = this.parseIdentifier(true);
+      let isDefaultfrom = false;
+      if (specifier.exported.name === "default" && this.isContextual("from")) {
+        isDefaultfrom = true;
+        const lookaheadState = this.lookahead();
+        if (
+          lookaheadState.value === "=" ||
+          lookaheadState.type === tt.semi ||
+          lookaheadState.type === tt.eof ||
+          lookaheadState.type === tt.braceR ||
+          lineBreak.test(
+            this.input.slice(lookaheadState.lastTokEnd, lookaheadState.start),
+          )
+        ) {
+          node.declaration = this.parseMaybeAssign();
+          this.checkExport(node, true, true);
+          return this.finishNode(node, "ExportDefaultDeclaration");
+        }
+      }
+      this.expectPlugin("exportDefaultFrom");
       const specifiers = [this.finishNode(specifier, "ExportDefaultSpecifier")];
       node.specifiers = specifiers;
-      if (this.match(tt.comma) && this.lookahead().type === tt.star) {
-        this.expect(tt.comma);
-        const specifier = this.startNode();
-        this.expect(tt.star);
-        this.expectContextual("as");
-        specifier.exported = this.parseIdentifier();
-        specifiers.push(this.finishNode(specifier, "ExportNamespaceSpecifier"));
-      } else {
-        this.parseExportSpecifiersMaybe(node);
+      if (!isDefaultfrom) {
+        if (this.match(tt.comma) && this.lookahead().type === tt.star) {
+          this.expect(tt.comma);
+          const specifier = this.startNode();
+          this.expect(tt.star);
+          this.expectContextual("as");
+          specifier.exported = this.parseIdentifier();
+          specifiers.push(
+            this.finishNode(specifier, "ExportNamespaceSpecifier"),
+          );
+        } else {
+          this.parseExportSpecifiersMaybe(node);
+        }
       }
+
       this.parseExportFrom(node, true);
     } else if (this.eat(tt._default)) {
       // export default ...
diff --git a/packages/babylon/test/fixtures/esprima/es2015-export-declaration/invalid-export-default/options.json b/packages/babylon/test/fixtures/esprima/es2015-export-declaration/invalid-export-default/options.json
index 689ff73f73f7..8ba464d69650 100644
--- a/packages/babylon/test/fixtures/esprima/es2015-export-declaration/invalid-export-default/options.json
+++ b/packages/babylon/test/fixtures/esprima/es2015-export-declaration/invalid-export-default/options.json
@@ -1,3 +1,3 @@
 {
-  "throws": "This experimental syntax requires enabling the parser plugin: 'exportDefaultFrom' (1:7)"
+  "throws": "This experimental syntax requires enabling the parser plugin: 'exportDefaultFrom' (1:15)"
 }
diff --git a/packages/babylon/test/fixtures/experimental/_no-plugin/export-default/options.json b/packages/babylon/test/fixtures/experimental/_no-plugin/export-default/options.json
index e306a4f34cbf..98c70928d7ab 100644
--- a/packages/babylon/test/fixtures/experimental/_no-plugin/export-default/options.json
+++ b/packages/babylon/test/fixtures/experimental/_no-plugin/export-default/options.json
@@ -1,4 +1,4 @@
 {
-  "throws": "This experimental syntax requires enabling the parser plugin: 'exportDefaultFrom' (1:7)",
+  "throws": "This experimental syntax requires enabling the parser plugin: 'exportDefaultFrom' (1:9)",
   "plugins": []
 }