From b1fb98fb9b7b21131b9976d1871ad8d77d2a5c0b Mon Sep 17 00:00:00 2001
From: tatsuya-asami <asami.tatsuya@commune.co.jp>
Date: Sat, 9 May 2026 15:01:47 +0900
Subject: [PATCH] [compiler]: add `useFormContext` to react-hook-form known
 incompatible APIs

#34027 added a check for react-hook-form's `useForm().watch`, but not
`useFormContext().watch`. The same `watch` function is exposed via
`useFormContext()` and has the same memoization incompatibility, also
discussed in the community at
https://github.com/orgs/react-hook-form/discussions/12524.
---
 .../src/HIR/DefaultModuleTypeProvider.ts       | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/compiler/packages/babel-plugin-react-compiler/src/HIR/DefaultModuleTypeProvider.ts b/compiler/packages/babel-plugin-react-compiler/src/HIR/DefaultModuleTypeProvider.ts
index 106fce615c44..9c27696396ad 100644
--- a/compiler/packages/babel-plugin-react-compiler/src/HIR/DefaultModuleTypeProvider.ts
+++ b/compiler/packages/babel-plugin-react-compiler/src/HIR/DefaultModuleTypeProvider.ts
@@ -65,6 +65,24 @@ export function defaultModuleTypeProvider(
               },
             },
           },
+          useFormContext: {
+            kind: 'hook',
+            returnType: {
+              kind: 'object',
+              properties: {
+                // Only the `watch()` function returned by react-hook-form's `useFormContext()` API is incompatible
+                watch: {
+                  kind: 'function',
+                  positionalParams: [],
+                  restParam: Effect.Read,
+                  calleeEffect: Effect.Read,
+                  returnType: {kind: 'type', name: 'Any'},
+                  returnValueKind: ValueKind.Mutable,
+                  knownIncompatible: `React Hook Form's \`useFormContext()\` API returns a \`watch()\` function which cannot be memoized safely.`,
+                },
+              },
+            },
+          },
         },
       };
     }