fix #1082: missing space before "Promise" when minifying

CHANGELOG.md

@@ -1,5 +1,11 @@
 # Changelog
 
+## Unreleased
+
+* Fix a missing space before internal `import()` when minifying ([#1082](https://github.com/evanw/esbuild/issues/1082))
+
+    Internal `import()` of a CommonJS module inside the bundle turns into a call to `Promise.resolve().then(() => require())`. However, a space was not inserted before the `Promise` token when minifying, which could lead to a syntax error. This bug has been fixed.
+
 ## 0.11.0
 
 **This release contains backwards-incompatible changes.** Since esbuild is before version 1.0.0, these changes have been released as a new minor version to reflect this (as [recommended by npm](https://docs.npmjs.com/cli/v6/using-npm/semver/)). You should either be pinning the exact version of `esbuild` in your `package.json` file or be using a version range syntax that only accepts patch upgrades such as `~0.10.0`. See the documentation about [semver](https://docs.npmjs.com/cli/v6/using-npm/semver/) for more information.

internal/js_printer/js_printer.go

@@ -1279,6 +1279,7 @@ func (p *printer) printRequireOrImportExpr(importRecordIndex uint32, leadingInte
 
 	// Internal "require()" or "import()"
 	if record.Kind == ast.ImportDynamic {
+		p.printSpaceBeforeIdentifier()
 		p.print("Promise.resolve()")
 		level = p.printDotThenPrefix()
 		defer p.printDotThenSuffix()

scripts/end-to-end-tests.js

@@ -1375,6 +1375,16 @@
     }),
   )
 
+  // This shouldn't cause a syntax error
+  // https://github.com/evanw/esbuild/issues/1082
+  tests.push(
+    test(['in.js', '--outfile=node.js', '--minify', '--bundle'], {
+      'in.js': `
+        return import('./in.js')
+      `,
+    })
+  )
+
   // Tests for "arguments" scope issues
   tests.push(
     test(['in.js', '--outfile=node.js', '--minify'], {