Syncing to arcanist

Fixing format for CI. Once this goes green, I'll land it.

Reordering certain code blocks, general clean-up of the patch.

Fix final test cases.

Fixing failing test case.

Format fix.

In D152818#4442116, @rjmccall wrote:

Does https://reviews.llvm.org/D143241 solve the original problem here, or is there something deeper?

Including __undef_macro in more header files - anywhere that move, refresh, or erase are used. This should fix the gcc compat problem.

Rebase

I've opened an issue (https://github.com/llvm/llvm-project/issues/63063) where we hit the same assertion. There's a smaller test case, and we've done enough investigation that we understand the problem. I'd be happy to discuss over on the issue as well.

Updating testcase to use NASTY_MACROS

Gentle ping.

Updating test cases to use nasty_macros.compile.pass.cpp instead of IBM-specific tests.

Adding an additional test case that was fixed by the same update.

Updating diff with more context.

Updating diff with more context.

There was a fix for nasty_macros.compile.pass.cpp in a recent AIX update. I've put up https://reviews.llvm.org/D148040 to revert the XFAILs. Once that lands, I'll update this patch to put the test cases there.

Before approving I really like to know why this only affects <filesystem>. I'm slightly wary to add work-arounds for unrelated external libaries (even when curses is quite Standard).

Updating formatting.

Updating implementation by putting macros within LIBCPP_PUSH_MACROS and LIBCPP_POP_MACROS

Addressing reviewer comment to rename testcase and generalizing __undef_macros to work for all platforms.

Update to assertions for z/OS case.

Reverting previous directive change.

Addressing review comments - spacing, updates to run lines, updates to a directive.

Opting out of clang ABI change in FieldPacked bool on AIX.

Adding run lines for AIX & z/OS, and updating comment line length.

Updating comment

Removed extra empty line.

Removing comment to allow for more generic use.