[PATCH] D67678: PR17164: Change clang's default behavior from -flax-vector-conversions=all to -flax-vector-conversions=integer.

[Richard Smith - zygoloid via Phabricator via cfe-commits]

rsmith added a comment.

In D67678#1856229 <https://reviews.llvm.org/D67678#1856229>, @rsmith wrote:

> In D67678#1836953 <https://reviews.llvm.org/D67678#1836953>, @dexonsmith wrote:
>
>> In D67678#1836922 <https://reviews.llvm.org/D67678#1836922>, @rsmith wrote:
>>
>>> If there's no timeline to update the macOS SDK, then perhaps we could add a hack to Clang to allow these conversions only in limited contexts (the specific parts of the macOS SDK that are relying on them). Do you know how many such places there might be? If it's just a few functions, we could match against the function names, or depending on what `SIMD_CFUNC` expands to, perhaps we could match that. Failing that, we could set a platform-specific default or similar.
>>
>> A hack like this sounds pragmatic to me.  An initial look suggests it's a small number of frameworks; I suspect many functions, but we could potentially match on partial file path or `SIMD_CFUNC`.  We need a deeper audit across our internal stack to be sure, though.  I don't think we'll have bandwidth for that until ~late February.
>
> OK, that seems fine to me. I don't want this to miss another release if we can avoid it, but that should give plenty of time to iterate on something that keeps your SDK building :)

@dexonsmith Ping, I'd like to get this done for the Clang 12 release; what do we need to do to make sure we're not causing problems for the macOS SDK?


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