third_party/llvm-project/libcxx/test/libcxx/clang_query/abi_tag_on_virtual.query

#===------------------------------------------------------------------------===#
#
# Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
# See https://llvm.org/LICENSE.txt for license information.
# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
#
#===------------------------------------------------------------------------===#

# This clang-query test ensures that we don't place an abi_tag attribute on
# virtual functions. This can happen by mistakenly applying a macro like
# _LIBCPP_HIDE_FROM_ABI on a virtual function.
#
# The problem is that arm64e pointer authentication extensions use the mangled
# name of the function to sign the function pointer in the vtable, which means
# that the ABI tag effectively influences how the pointers are signed.
#
# This can lead to PAC failures when passing an object that holds one of these
# pointers in its vtable across an ABI boundary if the two sides have been compiled
# with different versions of libc++: one side will sign the pointer using one function
# mangling (with one ABI tag), and the other side will authenticate the pointer expecting
# it to have a different mangled name due to the ABI tag being different, which will crash.
#
# This test ensures that we don't re-introduce this issue in the code base.

match
cxxMethodDecl(isVirtual(),
              hasAttr("attr::AbiTag"),
              unless(isExpansionInSystemHeader())
             )