From b3690da549fb2255754c00e9531927910bb3b781 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mateusz=20Burzy=C5=84ski?= <mateuszburzynski@gmail.com>
Date: Mon, 6 Oct 2025 00:00:12 +0200
Subject: [PATCH] Consistently resolve to the `errorType` on `arguments` with
 error

---
 src/compiler/checker.ts                       |  2 +-
 ...itializerOrStaticInitializationBlock.types | 64 +++++++++----------
 2 files changed, 33 insertions(+), 33 deletions(-)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index cbdbd55660bcd..48bc0da113816 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -30975,7 +30975,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
         checkIdentifierCalculateNodeCheckFlags(node, symbol);
 
         if (symbol === argumentsSymbol) {
-            if (isInPropertyInitializerOrClassStaticBlock(node)) {
+            if (isInPropertyInitializerOrClassStaticBlock(node, /*ignoreArrowFunctions*/ true)) {
                 return errorType;
             }
             return getTypeOfSymbol(symbol);
diff --git a/tests/baselines/reference/argumentsUsedInClassFieldInitializerOrStaticInitializationBlock.types b/tests/baselines/reference/argumentsUsedInClassFieldInitializerOrStaticInitializationBlock.types
index daf115ded7c38..99c13629e5b7c 100644
--- a/tests/baselines/reference/argumentsUsedInClassFieldInitializerOrStaticInitializationBlock.types
+++ b/tests/baselines/reference/argumentsUsedInClassFieldInitializerOrStaticInitializationBlock.types
@@ -116,12 +116,12 @@ function D() {
 >  : ^^^^^^^^
 
      a = () => arguments  // should error
->a : () => IArguments
->  : ^^^^^^^^^^^^^^^^
->() => arguments : () => IArguments
->                : ^^^^^^^^^^^^^^^^
->arguments : IArguments
->          : ^^^^^^^^^^
+>a : () => any
+>  : ^^^^^^^^^
+>() => arguments : () => any
+>                : ^^^^^^^^^
+>arguments : any
+>          : ^^^
   }
 }
 
@@ -142,18 +142,18 @@ function D1() {
 >                                                                                                                                                                                          : ^^^^^^^^^^
 
       arguments;    // should error
->arguments : IArguments
->          : ^^^^^^^^^^
+>arguments : any
+>          : ^^^
 
       const b = () => {
->b : () => IArguments
->  : ^^^^^^^^^^^^^^^^
->() => {        return arguments;     // should error      } : () => IArguments
->                                                            : ^^^^^^^^^^^^^^^^
+>b : () => any
+>  : ^^^^^^^^^
+>() => {        return arguments;     // should error      } : () => any
+>                                                            : ^^^^^^^^^
 
         return arguments;     // should error
->arguments : IArguments
->          : ^^^^^^^^^^
+>arguments : any
+>          : ^^^
       }
 
       function f() {
@@ -286,16 +286,16 @@ function D5() {
 >  : ^^^^^^^^
 
      a = (() => { return arguments; })()  // should error
->a : IArguments
->  : ^^^^^^^^^^
->(() => { return arguments; })() : IArguments
->                                : ^^^^^^^^^^
->(() => { return arguments; }) : () => IArguments
->                              : ^^^^^^^^^^^^^^^^
->() => { return arguments; } : () => IArguments
->                            : ^^^^^^^^^^^^^^^^
->arguments : IArguments
->          : ^^^^^^^^^^
+>a : any
+>  : ^^^
+>(() => { return arguments; })() : any
+>                                : ^^^
+>(() => { return arguments; }) : () => any
+>                              : ^^^^^^^^^
+>() => { return arguments; } : () => any
+>                            : ^^^^^^^^^
+>arguments : any
+>          : ^^^
   }
 }
 
@@ -310,14 +310,14 @@ function D6() {
 >  : ^^^^^^^^
 
      a = (x = arguments) => {}    // should error
->a : (x?: IArguments) => void
->  : ^ ^^^^^^^^^^^^^^^^^^^^^^
->(x = arguments) => {} : (x?: IArguments) => void
->                      : ^ ^^^^^^^^^^^^^^^^^^^^^^
->x : IArguments
->  : ^^^^^^^^^^
->arguments : IArguments
->          : ^^^^^^^^^^
+>a : (x?: any) => void
+>  : ^ ^^^^^^^^^^^^^^^
+>(x = arguments) => {} : (x?: any) => void
+>                      : ^ ^^^^^^^^^^^^^^^
+>x : any
+>  : ^^^
+>arguments : any
+>          : ^^^
   }
 }