fix(44466): Fixes parsing contextual keyword casts as arrow functions

src/compiler/parser.ts

@@ -4538,6 +4538,10 @@ namespace ts {
                 // isn't actually allowed, but we want to treat it as a lambda so we can provide
                 // a good error message.
                 if (isModifierKind(second) && second !== SyntaxKind.AsyncKeyword && lookAhead(nextTokenIsIdentifier)) {
+                    if (lookAhead(() => nextToken() === SyntaxKind.AsKeyword)) {
+                        // https://github.com/microsoft/TypeScript/issues/44466
+                        return Tristate.False;
+                    }
                     return Tristate.True;
                 }
 

tests/baselines/reference/overrideParenVariable.js

@@ -0,0 +1,8 @@
+//// [overrideParenVariable.ts]
+
+let override: any;
+export const a = (override as number);
+
+//// [overrideParenVariable.js]
+
+export const a = override;

tests/cases/compiler/readonlyParenCast.ts

@@ -0,0 +1,5 @@
+//@target: ES5
+
+let readonly: any;
+
+export const a = (readonly as number);