Merge pull request #42060 from xedin/csapply-remove-unused-var

[CSApply] NFC: Remove unused `cs` variable

Author: xedin

lib/Sema/CSApply.cpp

@@ -6020,7 +6020,6 @@ static Expr *buildElementConversion(ExprRewriter &rewriter,
                                     Type destType, bool bridged,
                                     ConstraintLocatorBuilder locator,
                                     Expr *element) {
-  auto &cs = rewriter.getConstraintSystem();
   if (bridged &&
       TypeChecker::typeCheckCheckedCast(srcType, destType,
                                         CheckedCastContextKind::None,