From 4f01bac16d6e1c549d43a2d6b60ceff7634e43b8 Mon Sep 17 00:00:00 2001
From: Kristiyan Kostadinov <crisbeto@users.noreply.github.com>
Date: Sun, 27 Mar 2022 12:28:48 +0200
Subject: [PATCH] build: add lint rule to disallow type-only imports/exports
 (#24678)

Type-only imports and exports don't work with Closure so we can't use them.
---
 .../noTypeOnlyImportExportRule.ts             | 19 +++++++++++++++++++
 tslint.json                                   |  1 +
 2 files changed, 20 insertions(+)
 create mode 100644 tools/tslint-rules/noTypeOnlyImportExportRule.ts

diff --git a/tools/tslint-rules/noTypeOnlyImportExportRule.ts b/tools/tslint-rules/noTypeOnlyImportExportRule.ts
new file mode 100644
index 000000000000..503a368060b3
--- /dev/null
+++ b/tools/tslint-rules/noTypeOnlyImportExportRule.ts
@@ -0,0 +1,19 @@
+import ts from 'typescript';
+import * as Lint from 'tslint';
+
+/** Lint rule that doesn't allow usages of type-only imports/exports. */
+export class Rule extends Lint.Rules.AbstractRule {
+  apply(sourceFile: ts.SourceFile) {
+    return this.applyWithFunction(sourceFile, walker);
+  }
+}
+
+function walker(context: Lint.WalkContext): void {
+  (function visitNode(node: ts.Node) {
+    if (ts.isTypeOnlyImportOrExportDeclaration(node)) {
+      context.addFailureAtNode(node, 'Type-only symbols are not allowed.');
+    }
+
+    ts.forEachChild(node, visitNode);
+  })(context.sourceFile);
+}
diff --git a/tslint.json b/tslint.json
index b8ab009b44db..1ad9106d5d67 100644
--- a/tslint.json
+++ b/tslint.json
@@ -75,6 +75,7 @@
     // Custom Rules
     "ts-loader": true,
     "no-exposed-todo": true,
+    "no-type-only-import-export": true,
     "no-private-getters": [true, "^_"],
     "no-undecorated-base-class-di": true,
     "no-undecorated-class-with-angular-features": true,