[compiler] Surface unused opt out directives in eslint

This PR updates the eslint plugin to report unused opt out directives.
One of the downsides of the opt out directive is that it opts the
component/hook out of compilation forever, even if the underlying issue
was fixed in product code or fixed in the compiler.

ghstack-source-id: e288fff57efb31c4e16ad5d74a0cc1d72bbf78db
Pull Request resolved: #30721

compiler/packages/eslint-plugin-react-compiler/__tests__/ReactCompilerRule-test.ts

@@ -104,6 +104,17 @@ const tests: CompilerTestCases = {
         }
       `,
     },
+    {
+      name: "'use no forget' directive is respected when errors are present",
+      code: normalizeIndent`
+        let count = 0;
+        function Component() {
+          'use no forget';
+          count++;
+          return <div>Hello world {count}</div>
+        }
+      `,
+    },
   ],
   invalid: [
     {
@@ -199,6 +210,27 @@ const tests: CompilerTestCases = {
         },
       ],
     },
+    {
+      name: "Unused 'use no forget' directive is reported when no errors are present",
+      code: normalizeIndent`
+        function Component() {
+          'use no forget';
+          return <div>Hello world</div>
+        }
+      `,
+      errors: [
+        {
+          message: "Unused 'use no forget' directive",
+          suggestions: [
+            {
+              output:
+                // yuck
+                '\nfunction Component() {\n  \n  return <div>Hello world</div>\n}\n',
+            },
+          ],
+        },
+      ],
+    },
   ],
 };
 

compiler/packages/eslint-plugin-react-compiler/src/rules/ReactCompilerRule.ts

@@ -15,10 +15,12 @@ import BabelPluginReactCompiler, {
   ErrorSeverity,
   parsePluginOptions,
   validateEnvironmentConfig,
+  OPT_OUT_DIRECTIVES,
   type PluginOptions,
 } from 'babel-plugin-react-compiler/src';
 import {Logger} from 'babel-plugin-react-compiler/src/Entrypoint';
 import type {Rule} from 'eslint';
+import {Statement} from 'estree';
 import * as HermesParser from 'hermes-parser';
 
 type CompilerErrorDetailWithLoc = Omit<CompilerErrorDetailOptions, 'loc'> & {
@@ -146,6 +148,7 @@ const rule: Rule.RuleModule = {
         userOpts['__unstable_donotuse_reportAllBailouts'];
     }
 
+    let shouldReportUnusedOptOutDirective = true;
     const options: PluginOptions = {
       ...parsePluginOptions(userOpts),
       ...COMPILER_OPTIONS,
@@ -155,6 +158,7 @@ const rule: Rule.RuleModule = {
       logEvent: (filename, event): void => {
         userLogger?.logEvent(filename, event);
         if (event.kind === 'CompileError') {
+          shouldReportUnusedOptOutDirective = false;
           const detail = event.detail;
           const suggest = makeSuggestions(detail);
           if (__unstable_donotuse_reportAllBailouts && event.fnLoc != null) {
@@ -269,7 +273,52 @@ const rule: Rule.RuleModule = {
         /* errors handled by injected logger */
       }
     }
-    return {};
+
+    function reportUnusedOptOutDirective(stmt: Statement) {
+      if (
+        stmt.type === 'ExpressionStatement' &&
+        stmt.expression.type === 'Literal' &&
+        typeof stmt.expression.value === 'string' &&
+        OPT_OUT_DIRECTIVES.has(stmt.expression.value) &&
+        stmt.loc != null
+      ) {
+        context.report({
+          message: `Unused '${stmt.expression.value}' directive`,
+          loc: stmt.loc,
+          suggest: [
+            {
+              desc: 'Remove the directive',
+              fix(fixer) {
+                return fixer.remove(stmt);
+              },
+            },
+          ],
+        });
+      }
+    }
+    if (shouldReportUnusedOptOutDirective) {
+      return {
+        FunctionDeclaration(fnDecl) {
+          for (const stmt of fnDecl.body.body) {
+            reportUnusedOptOutDirective(stmt);
+          }
+        },
+        ArrowFunctionExpression(fnExpr) {
+          if (fnExpr.body.type === 'BlockStatement') {
+            for (const stmt of fnExpr.body.body) {
+              reportUnusedOptOutDirective(stmt);
+            }
+          }
+        },
+        FunctionExpression(fnExpr) {
+          for (const stmt of fnExpr.body.body) {
+            reportUnusedOptOutDirective(stmt);
+          }
+        },
+      };
+    } else {
+      return {};
+    }
   },
 };