From 21244e7000dbbe8093dfd9e0c56fac9f97276c82 Mon Sep 17 00:00:00 2001
From: Evan Wallace <evan.exe@gmail.com>
Date: Sat, 20 Jun 2020 10:35:52 -0700
Subject: [PATCH] fix #190: ensure re-exported default aliases aren't renamed

---
 CHANGELOG.md                     |  6 +++
 internal/bundler/bundler_test.go | 63 ++++++++++++++++++++++++++++++++
 internal/parser/parser.go        |  9 +++--
 3 files changed, 75 insertions(+), 3 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index d9d56f0b775..711b5815f28 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,11 @@
 # Changelog
 
+## Unreleased
+
+* Fix re-export statements ([#190](https://github.com/evanw/esbuild/issues/190))
+
+    The previous release caused a regression due to some behind-the-scenes work for the upcoming code splitting feature. The re-export alias in statements of the form `export { foo as bar } from 'path'` could sometimes incorrectly be renamed to something else, such as `foo` becoming `foo2`. This release fixes the bug.
+
 ## 0.5.5
 
 * Implement logical assignment operator transforms
diff --git a/internal/bundler/bundler_test.go b/internal/bundler/bundler_test.go
index bafeb1b0905..6387fbbef47 100644
--- a/internal/bundler/bundler_test.go
+++ b/internal/bundler/bundler_test.go
@@ -5310,3 +5310,66 @@ export {
 		},
 	})
 }
+
+func TestReExportDefault(t *testing.T) {
+	expectBundled(t, bundled{
+		files: map[string]string{
+			"/entry.js": `
+				export {default as foo} from './foo'
+				export {default as bar} from './bar'
+			`,
+			"/foo.js": `
+				export default 'foo'
+			`,
+			"/bar.js": `
+				export default 'bar'
+			`,
+		},
+		entryPaths: []string{"/entry.js"},
+		parseOptions: parser.ParseOptions{
+			IsBundling: true,
+		},
+		bundleOptions: BundleOptions{
+			IsBundling:    true,
+			AbsOutputFile: "/out.js",
+		},
+		expected: map[string]string{
+			"/out.js": `// /foo.js
+const foo_default = "foo";
+
+// /bar.js
+const bar_default = "bar";
+
+// /entry.js
+export {
+  bar_default as bar,
+  foo_default as foo
+};
+`,
+		},
+	})
+}
+
+func TestReExportDefaultNoBundle(t *testing.T) {
+	expectBundled(t, bundled{
+		files: map[string]string{
+			"/entry.js": `
+				export {default as foo} from './foo'
+				export {default as bar} from './bar'
+			`,
+		},
+		entryPaths: []string{"/entry.js"},
+		parseOptions: parser.ParseOptions{
+			IsBundling: false,
+		},
+		bundleOptions: BundleOptions{
+			IsBundling:    false,
+			AbsOutputFile: "/out.js",
+		},
+		expected: map[string]string{
+			"/out.js": `export {default as foo} from "./foo";
+export {default as bar} from "./bar";
+`,
+		},
+	})
+}
diff --git a/internal/parser/parser.go b/internal/parser/parser.go
index 87df4843dad..409e109c871 100644
--- a/internal/parser/parser.go
+++ b/internal/parser/parser.go
@@ -6965,7 +6965,7 @@ func (p *parser) visitAndAppendStmt(stmts []ast.Stmt, stmt ast.Stmt) []ast.Stmt
 		}
 
 	case *ast.SExportClause:
-		// "export {foo}
+		// "export {foo}"
 		for i, item := range s.Items {
 			name := p.loadNameFromRef(item.Name.Ref)
 			ref := p.findSymbol(name).ref
@@ -6980,10 +6980,13 @@ func (p *parser) visitAndAppendStmt(stmts []ast.Stmt, stmt ast.Stmt) []ast.Stmt
 		p.currentScope.Generated = append(p.currentScope.Generated, s.NamespaceRef)
 		p.recordDeclaredSymbol(s.NamespaceRef)
 
-		// This is a re-export and the names are symbols in another file
+		// This is a re-export and the symbols created here are used to reference
+		// names in another file. This means the symbols are really aliases. The
+		// symbols are marked as "unbound" so that they aren't accidentally renamed
+		// by the code that avoids symbol name collisions.
 		for i, item := range s.Items {
 			name := p.loadNameFromRef(item.Name.Ref)
-			ref := p.newSymbol(ast.SymbolOther, name)
+			ref := p.newSymbol(ast.SymbolUnbound, name)
 			p.currentScope.Generated = append(p.currentScope.Generated, ref)
 			p.recordDeclaredSymbol(ref)
 			s.Items[i].Name.Ref = ref