remove an extra "use strict" directive (#2264)

Author: evanw

CHANGELOG.md

@@ -39,6 +39,10 @@
 
     Previously bundling with esbuild when inside a sandbox environment which does not have permission to access the parent directory did not work because esbuild would try to read the directory to search for a `node_modules` folder and would then fail the build when that failed. In practice this caused issues with running esbuild with `sandbox-exec` on macOS. With this release, esbuild will treat directories with permission failures as empty to allow for the `node_modules` search to continue past the denied directory and into its parent directory. This means it should now be possible to bundle with esbuild in these situations. This fix is similar to the fix in version 0.9.1 but is for `EPERM` while that fix was for `EACCES`.
 
+* Remove an irrelevant extra `"use strict"` directive ([#2264](https://github.com/evanw/esbuild/issues/2264))
+
+    The presence of a `"use strict"` directive in the output file is controlled by the presence of one in the entry point. However, there was a bug that would include one twice if the output format is ESM. This bug has been fixed.
+
 ## 0.14.39
 
 * Fix code generation for `export default` and `/* @__PURE__ */` call ([#2203](https://github.com/evanw/esbuild/issues/2203))

internal/bundler/bundler_default_test.go

@@ -2788,6 +2788,23 @@ func TestUseStrictDirectiveBundleIssue1837(t *testing.T) {
 	})
 }
 
+func TestUseStrictDirectiveBundleIssue2264(t *testing.T) {
+	default_suite.expectBundled(t, bundled{
+		files: map[string]string{
+			"/entry.js": `
+				'use strict'
+				export let a = 1
+			`,
+		},
+		entryPaths: []string{"/entry.js"},
+		options: config.Options{
+			Mode:          config.ModeBundle,
+			AbsOutputFile: "/out.js",
+			OutputFormat:  config.FormatESModule,
+		},
+	})
+}
+
 func TestNoOverwriteInputFileError(t *testing.T) {
 	default_suite.expectBundled(t, bundled{
 		files: map[string]string{

internal/bundler/linker.go

@@ -4363,6 +4363,7 @@ func (c *linkerContext) generateEntryPointTailJS(
 	}
 
 	tree := repr.AST
+	tree.Directive = ""
 	tree.Parts = []js_ast.Part{{Stmts: stmts}}
 
 	// Indent the file if everything is wrapped in an IIFE

internal/bundler/snapshots/snapshots_default.txt

@@ -3779,6 +3779,17 @@ TestUseStrictDirectiveBundleIssue1837
   console.log(require_cjs());
 })();
 
+================================================================================
+TestUseStrictDirectiveBundleIssue2264
+---------- /out.js ----------
+"use strict";
+
+// entry.js
+var a = 1;
+export {
+  a
+};
+
 ================================================================================
 TestUseStrictDirectiveMinifyNoBundle
 ---------- /out.js ----------