fix #2741: --packages=external + subpath imports

CHANGELOG.md

@@ -1,5 +1,11 @@
 # Changelog
 
+## Unreleased
+
+* Do not mark subpath imports as external with `--packages=external` ([#2741](https://github.com/evanw/esbuild/issues/2741))
+
+    Node has a feature called [subpath imports](https://nodejs.org/api/packages.html#subpath-imports) where special import paths that start with `#` are resolved using the `imports` field in the `package.json` file of the enclosing package. The intent of the newly-added `--packages=external` setting is to exclude a package's dependencies from the bundle. Since a package's subpath imports are only accessible within that package, it's wrong for them to be affected by `--packages=external`. This release changes esbuild so that `--packages=external` no longer affects subpath imports.
+
 ## 0.16.5
 
 * Make it easy to exclude all packages from a bundle ([#1958](https://github.com/evanw/esbuild/issues/1958), [#1975](https://github.com/evanw/esbuild/issues/1975), [#2164](https://github.com/evanw/esbuild/issues/2164), [#2246](https://github.com/evanw/esbuild/issues/2246), [#2542](https://github.com/evanw/esbuild/issues/2542))

internal/bundler/bundler_default_test.go

@@ -7083,19 +7083,28 @@ NOTE: You can either keep the import assertion and only use the "default" import
 func TestExternalPackages(t *testing.T) {
 	loader_suite.expectBundled(t, bundled{
 		files: map[string]string{
-			"/entry.js": `
+			"/project/entry.js": `
 				import 'pkg1'
 				import './file'
 				import './node_modules/pkg2/index.js'
+				import '#pkg3'
 			`,
-			"/file.js": `
+			"/project/package.json": `{
+				"imports": {
+					"#pkg3": "./libs/pkg3.js"
+				}
+			}`,
+			"/project/file.js": `
 				console.log('file')
 			`,
-			"/node_modules/pkg2/index.js": `
+			"/project/node_modules/pkg2/index.js": `
 				console.log('pkg2')
 			`,
+			"/project/libs/pkg3.js": `
+				console.log('pkg3')
+			`,
 		},
-		entryPaths: []string{"/entry.js"},
+		entryPaths: []string{"/project/entry.js"},
 		options: config.Options{
 			Mode:             config.ModeBundle,
 			AbsOutputFile:    "/out.js",

internal/bundler/snapshots/snapshots_loader.txt

@@ -60,15 +60,18 @@ a:after {
 ================================================================================
 TestExternalPackages
 ---------- /out.js ----------
-// entry.js
+// project/entry.js
 import "pkg1";
 
-// file.js
+// project/file.js
 console.log("file");
 
-// node_modules/pkg2/index.js
+// project/node_modules/pkg2/index.js
 console.log("pkg2");
 
+// project/libs/pkg3.js
+console.log("pkg3");
+
 ================================================================================
 TestIndirectRequireMessage
 ---------- /out/array.js ----------

internal/resolver/resolver.go

@@ -360,7 +360,7 @@ func (rr *resolver) Resolve(sourceDir string, importPath string, kind ast.Import
 	}
 
 	// "import 'pkg'" when all packages are external (vs. "import './pkg'")
-	if r.options.ExternalPackages && IsPackagePath(importPath) && !r.fs.IsAbs(importPath) {
+	if r.options.ExternalPackages && IsPackagePath(importPath) && !r.fs.IsAbs(importPath) && !strings.HasPrefix(importPath, "#") {
 		if r.debugLogs != nil {
 			r.debugLogs.addNote("Marking this path as external because it's a package path")
 		}