build: check tooling scripts for compilation errors

.circleci/config.yml

@@ -395,6 +395,9 @@ jobs:
             pkg_json_version=$(node -pe "require('./package.json').version")
             expected_version="${pkg_json_version}-sha-$(git rev-parse --short HEAD)"
             yarn check-release-output ${expected_version}
+      - run:
+          name: Checking tooling scripts
+          command: yarn check-tools
 
       # TODO(devversion): replace this with bazel tests that run Madge. This is
       # cumbersome and doesn't guarantee no circular deps for other entry-points.

package.json

@@ -47,7 +47,8 @@
     "integration-tests:view-engine": "bazel test --test_tag_filters=view-engine-only --build_tests_only -- //integration/... -//integration/size-test/...",
     "integration-tests:size-test": "bazel test //integration/size-test/...",
     "check-mdc-tests": "ts-node --project scripts/tsconfig.json scripts/check-mdc-tests.ts",
-    "check-mdc-exports": "ts-node --project scripts/tsconfig.json scripts/check-mdc-exports.ts"
+    "check-mdc-exports": "ts-node --project scripts/tsconfig.json scripts/check-mdc-exports.ts",
+    "check-tools": "yarn tsc --project tools/tsconfig-ci.json"
   },
   "version": "11.2.0-next.0",
   "dependencies": {

tools/tsconfig-ci.json

@@ -0,0 +1,15 @@
+// A lot of the scripts under `tools` are run manually, rather than on the CI. As such, it's easy
+// to miss compilation errors in them. This config is used to verify the files on the CI. Note that
+// the compiler options are somewhat loose, which is intentional in order to mimic the default
+// options used by `ts-node` when running the scripts.
+{
+  "include": ["./**/*.ts"],
+  "exclude": ["./public_api_guard/**/*.ts"],
+  "compilerOptions": {
+    "outDir": "../dist/tools",
+    "lib": ["es2015"],
+    "skipLibCheck": true,
+    // Don't emit to the file system, because we only want to check for compilation errors.
+    "noEmit": true
+  }
+}

tools/tslint-rules/noUnescapedHtmlTagRule.ts

@@ -51,10 +51,10 @@ class NoUnescapedHtmlTagWalker extends Lint.RuleWalker {
     // Whether an opening backtick has been found without a closing pair
     let openBacktick = false;
 
-    for (const char of fullText) {
-      if (char === '`') {
+    for (let i = 0; i < fullText.length; i++) {
+      if (fullText[i] === '`') {
         openBacktick = !openBacktick;
-      } else if (matches.test(char) && !openBacktick) {
+      } else if (matches.test(fullText[i]) && !openBacktick) {
         return false;
       }
     }