From 46559d8ba3952cd31a7b4136f6b286a5aae2cf86 Mon Sep 17 00:00:00 2001
From: Evan Wallace <evan.exe@gmail.com>
Date: Sun, 19 Jul 2020 02:48:23 -0700
Subject: [PATCH] fix #273: span re-exported symbols across chunks

---
 CHANGELOG.md                               |  4 ++
 internal/bundler/bundler_splitting_test.go | 47 ++++++++++++++++++++++
 internal/bundler/linker.go                 | 14 ++-----
 3 files changed, 55 insertions(+), 10 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 857b16bc1c..d16ae25db3 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,10 @@
 
     The install script now downloads the binary directly from npmjs.org instead of using the `npm` command to install the package. This should be more compatible with unusual node environments (e.g. having multiple old copies of npm installed).
 
+* Fix a code splitting bug with re-exported symbols ([#273](https://github.com/evanw/esbuild/issues/273))
+
+    Re-exporting a symbol in an entry point didn't correctly track the cross-chunk dependency, which caused the output file to be missing a required import. This bug has been fixed.
+
 ## 0.6.3
 
 * Fix `/* @__PURE__ */` IIFEs at start of statement ([#258](https://github.com/evanw/esbuild/issues/258))
diff --git a/internal/bundler/bundler_splitting_test.go b/internal/bundler/bundler_splitting_test.go
index 673daffc53..a3963b7dfd 100644
--- a/internal/bundler/bundler_splitting_test.go
+++ b/internal/bundler/bundler_splitting_test.go
@@ -530,3 +530,50 @@ console.log(bar());
 		},
 	})
 }
+
+func TestSplittingReExportIssue273(t *testing.T) {
+	expectBundled(t, bundled{
+		files: map[string]string{
+			"/a.js": `
+				export const a = 1
+			`,
+			"/b.js": `
+				export { a } from './a'
+			`,
+		},
+		entryPaths: []string{"/a.js", "/b.js"},
+		options: config.Options{
+			IsBundling:    true,
+			CodeSplitting: true,
+			OutputFormat:  config.FormatESModule,
+			AbsOutputDir:  "/out",
+		},
+		expected: map[string]string{
+			"/out/a.js": `import {
+  a
+} from "./chunk.xL6KqlYO.js";
+
+// /a.js
+export {
+  a
+};
+`,
+			"/out/b.js": `import {
+  a
+} from "./chunk.xL6KqlYO.js";
+
+// /b.js
+export {
+  a
+};
+`,
+			"/out/chunk.xL6KqlYO.js": `// /a.js
+const a = 1;
+
+export {
+  a
+};
+`,
+		},
+	})
+}
diff --git a/internal/bundler/linker.go b/internal/bundler/linker.go
index 1d4316c37b..39fbda8723 100644
--- a/internal/bundler/linker.go
+++ b/internal/bundler/linker.go
@@ -576,14 +576,11 @@ func (c *linkerContext) computeCrossChunkDependencies(chunks []chunkMeta) {
 						continue
 					}
 
+					// If this is imported from another file, follow the import
+					// reference and reference the symbol in that file instead
 					if importToBind, ok := fileMeta.importsToBind[ref]; ok {
-						// If this is imported from another file, follow the import
-						// reference and reference the symbol in that file instead
 						ref = importToBind.ref
 						symbol = c.symbols.Get(ref)
-					} else if _, ok := file.ast.TopLevelSymbolToParts[ref]; !ok {
-						// Skip symbols that aren't imports or top-level symbols
-						continue
 					}
 
 					// If this is an ES6 import from a CommonJS file, it will become a
@@ -612,11 +609,8 @@ func (c *linkerContext) computeCrossChunkDependencies(chunks []chunkMeta) {
 		// Find all uses in this chunk of symbols from other chunks
 		importsFromOtherChunks := make(map[uint32][]ast.Ref)
 		for importRef := range chunkMetas[chunkIndex].imports {
-			otherChunkIndex, ok := topLevelDeclaredSymbolToChunk[importRef]
-			if !ok {
-				panic("Internal error")
-			}
-			if otherChunkIndex != uint32(chunkIndex) {
+			// Ignore uses that aren't top-level symbols
+			if otherChunkIndex, ok := topLevelDeclaredSymbolToChunk[importRef]; ok && otherChunkIndex != uint32(chunkIndex) {
 				importsFromOtherChunks[otherChunkIndex] = append(importsFromOtherChunks[otherChunkIndex], importRef)
 				chunkMetas[otherChunkIndex].exports[importRef] = true
 			}