only show no-undef errors for templates in gts files

lib/preprocessors/glimmer.js

@@ -122,6 +122,30 @@ function mapRange(messages, filename) {
 
   const lines = transformed.split('\n');
   const originalLines = original.split('\n');
+
+  // get template ranges to remove eslint messages that are inside the templates
+  const templateRanges = [];
+  let isInsideTemplate = false;
+  for (const [index, line] of lines.entries()) {
+    const lineHasOpeningTag = openingTemplateTagRegex.test(line);
+    const lineHasClosingTag = closingTemplateTagRegex.test(line);
+
+    if (lineHasOpeningTag) {
+      isInsideTemplate = true;
+      templateRanges.push({
+        startLine: index + 1,
+        endLine: index + 1,
+        startColumn: line.search(openingTemplateTagRegex) + 1,
+      });
+    }
+
+    if (lineHasClosingTag && isInsideTemplate) {
+      isInsideTemplate = false;
+      const match = line.match(closingTemplateTagRegex);
+      templateRanges.slice(-1)[0].endLine = index + 1;
+      templateRanges.slice(-1)[0].endColumn = match.index + match[0].length + 1;
+    }
+  }
 
   // this function assumes the original output and transformed output
   // are identical, minus the changes to transform `<template>` into the
@@ -135,7 +159,27 @@ function mapRange(messages, filename) {
     );
   }
 
-  return flattened.map((message) => {
+  const filtered = flattened.filter(
+    (it) =>
+      it.ruleId === 'no-undef' ||
+      // include if message wraps a template
+      templateRanges.some(
+        (tpl) =>
+          tpl.startLine >= it.line &&
+          tpl.startColumn >= it.column &&
+          tpl.endLine <= it.endLine &&
+          tpl.endColumn <= it.endColumn
+      ) ||
+      // exclude if message is within template (also when it ends on next line, column 1)
+      !templateRanges.some(
+        (tpl) =>
+          tpl.startLine <= it.line &&
+          tpl.startColumn <= it.column &&
+          (tpl.endLine >= it.endLine || (it.endLine === tpl.endLine + 1 && it.endColumn === 1))
+      )
+  );
+
+  return filtered.map((message) => {
     // 1. handle eslint diagnostics on single lines.
     if (message.line === message.endLine) {
       const originalLine = originalLines[message.line - 1];

tests/lib/rules-preprocessor/gjs-gts-processor-test.js

@@ -35,6 +35,7 @@ function initESLint(options) {
       plugins: ['ember'],
       extends: ['plugin:ember/recommended'],
       rules: {
+        'object-curly-spacing': ['error', 'always'],
         'lines-between-class-members': 'error',
         'no-undef': 'error',
         'no-unused-vars': 'error',
@@ -388,7 +389,7 @@ describe('multiple tokens in same file', () => {
   it('handles duplicate template tokens', async () => {
     const eslint = initESLint();
     const code = `
-      // comment Bad 
+      // comment Bad
 
       const tmpl = <template><Bad /></template>
     `;