rebase

add testcase

update testcase using utils/update_llc_test_checks.py

update comment in testcase

update test, remove description in release note

rebase to main

Hello Erichkeane, I have the access now, maybe I can push it by myself. Thanks again!

HerrCai0907 and congcongcai0907@163.com

I don't have write access now. Could you kindly help me to commit it?

rebase to main

add release note

Should I add release note in clang/docs/ReleaseNotes.rst or any other way?

add more testcase

I guess ut failed is not related with this PR?

I cannot find an example that throw error: expression contains unexpanded parameter pack 'T' in fold expression because code like (foo<T>(10 + (static_cast<U>(1))) + ...); can be unpack both T and U in same ... operator

The idea is that:

1. If function return an invalid ExprResult, this error should be handled in the callee
2. If function return valid Expr, the potential error should be handled in the caller, in this case, is ActOnExprStmt. If callee handles error, when caller find some error and want to output error message, the error in this expression has been processed and cause crash.

Thanks, you can use my name HerrCai0907 (congcongcai0907@163.com) as patch attribution.