react-i18next and TS2589: Type instantiation is excessively deep and possibly infinite.

README.md

react-i18next and TS2589: Type instantiation is excessively deep and possibly infinite.

The patch works both with tsc and next build, as described in the comments of the patch.

Inspired by

• i18next/react-i18next#1417 (comment)

typescript+4.7.4.patch

diff --git a/node_modules/typescript/lib/tsc.js b/node_modules/typescript/lib/tsc.js
index 4964bb7..8fa48e0 100644
--- a/node_modules/typescript/lib/tsc.js
+++ b/node_modules/typescript/lib/tsc.js
@@ -52730,7 +52730,8 @@ var ts;
             if (!couldContainTypeVariables(type)) {
                 return type;
             }
-            if (instantiationDepth === 100 || instantiationCount >= 5000000) {
+            // increase limit to make i18n type work @see https://github.com/i18next/react-i18next/issues/1417#issuecomment-983951906
+            if (instantiationDepth === 200 || instantiationCount >= 5000000) {
                 ts.tracing === null || ts.tracing === void 0 ? void 0 : ts.tracing.instant("checkTypes", "instantiateType_DepthLimit", { typeId: type.id, instantiationDepth: instantiationDepth, instantiationCount: instantiationCount });
                 error(currentNode, ts.Diagnostics.Type_instantiation_is_excessively_deep_and_possibly_infinite);
                 return errorType;
diff --git a/node_modules/typescript/lib/typescript.js b/node_modules/typescript/lib/typescript.js
index e8734a6..b6b6619 100644
--- a/node_modules/typescript/lib/typescript.js
+++ b/node_modules/typescript/lib/typescript.js
@@ -63632,7 +63632,21 @@ var ts;
             if (!couldContainTypeVariables(type)) {
                 return type;
             }
-            if (instantiationDepth === 100 || instantiationCount >= 5000000) {
+            /**
+             * increase limit to make i18n type work @see https://github.com/i18next/react-i18next/issues/1417#issuecomment-983951906
+             * 
+             * Why?
+             * 
+             * Because of how next validates types when running `next build`, we
+             * have to patch not only tsc.js but also this file.
+             * 
+             * @see https://github.com/vercel/next.js/blob/4cc7f11da2194aa9ffce4e04b8a0c6ee340f4f85/packages/next/build/index.ts#L176
+             * @see https://github.com/vercel/next.js/blob/4cc7f11da2194aa9ffce4e04b8a0c6ee340f4f85/packages/next/lib/verifyTypeScriptSetup.ts#L20-L24
+             * 
+             * And ignoring the build step is not a desired solution.
+             * @see https://nextjs.org/docs/api-reference/next.config.js/ignoring-typescript-errors
+             */
++            if (instantiationDepth === 200 || instantiationCount >= 5000000) {
                 // We have reached 100 recursive type instantiations, or 5M type instantiations caused by the same statement
                 // or expression. There is a very high likelyhood we're dealing with a combination of infinite generic types
                 // that perpetually generate new type identities, so we stop the recursion here by yielding the error type.