tools: non-Ascii linter for /lib only

Non-ASCII characters in /lib get compiled into the node binary,
and may bloat the binary size unnecessarily. A linter rule may
help prevent this.

PR-URL: https://github.com/nodejs/node/pull/18043
Fixes: https://github.com/nodejs/node/issues/11209
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Teddy Katz <teddy.katz@gmail.com>

1 files changed, 61 insertions, 0 deletions

diff --git a/tools/eslint-rules/non-ascii-character.js b/tools/eslint-rules/non-ascii-character.js
new file mode 100644
index 0000000000..e67aac7cd9
--- /dev/null
+++ b/tools/eslint-rules/non-ascii-character.js
@@ -0,0 +1,61 @@
+/**
+ * @fileOverview Any non-ASCII characters in lib/ will increase the size
+ *               of the compiled node binary. This linter rule ensures that
+ *               any such character is reported.
+ * @author Sarat Addepalli <sarat.addepalli@gmail.com>
+ */
+
+'use strict';
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+const nonAsciiRegexPattern = /[^\r\n\x20-\x7e]/;
+const suggestions = {
+  '’': '\'',
+  '‛': '\'',
+  '‘': '\'',
+  '“': '"',
+  '‟': '"',
+  '”': '"',
+  '«': '"',
+  '»': '"',
+  '—': '-'
+};
+
+module.exports = (context) => {
+
+  const reportIfError = (node, sourceCode) => {
+
+    const matches = sourceCode.text.match(nonAsciiRegexPattern);
+
+    if (!matches) return;
+
+    const offendingCharacter = matches[0];
+    const offendingCharacterPosition = matches.index;
+    const suggestion = suggestions[offendingCharacter];
+
+    let message = `Non-ASCII character '${offendingCharacter}' detected.`;
+
+    message = suggestion ?
+      `${message} Consider replacing with: ${suggestion}` :
+      message;
+
+    context.report({
+      node,
+      message,
+      loc: sourceCode.getLocFromIndex(offendingCharacterPosition),
+      fix: (fixer) => {
+        return fixer.replaceText(
+          node,
+          suggestion ? `${suggestion}` : ''
+        );
+      }
+    });
+  };
+
+  return {
+    Program: (node) => reportIfError(node, context.getSourceCode())
+  };
+};