[PATCH] D85802: [clang] Add -fc++-abi= flag for specifying which C++ ABI to use

[Leonard Chan via Phabricator via cfe-commits]

leonardchan added a comment.

In D85802#2331290 <https://reviews.llvm.org/D85802#2331290>, @rnk wrote:

> I'd like to point out that we used to have a very similar flag, but we removed it back in 2014: http://reviews.llvm.org/D2545
>
> Are you sure you need all the flexibility that this flag allows? For example, this will let users ask for the MSVC C++ ABI on Linux. I really don't want to support the mips, wasm, microsoft, or ios C++ ABI on arbitrary targets, and I don't want to have to teach clang to diagnose all the unsupported ways users can use this flag. The smaller we can make the space of options, the better, and the less conditional soup we'll have in the future.

Yeah I see how this can lead to a lot of complexity. Perhaps we can add some mechanism in Clang that determines which ABIs are supported for specific platforms? That is, when targetting Linux, Clang will diagnose an error if using `-fc++-abi=microsoft`. This could cover the case where a specific platform can support multiple ABIs, but those ABIs won't be supported by other platforms.


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https://reviews.llvm.org/D85802