[PATCH] D53879: Make libc++'s versioning namespace customizable

[Louis Dionne via Phabricator]

ldionne added inline comments.


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Comment at: CMakeLists.txt:685
+if (NOT LIBCXX_ABI_NAMESPACE STREQUAL "")
+  if (NOT LIBCXX_ABI_NAMESPACE MATCHES "__.*")
+    message(FATAL_ERROR "LIBCXX_ABI_NAMESPACE must be a reserved identifier.")
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EricWF wrote:
> ldionne wrote:
> > `__.+`? Or do we want to allow `__`?
> In addition do we want `_Foo`. My thinking is we should probably allow users to foot-gun themselves as much as they want. 
> 
> We should probably document that we make no promises that we don't introduce names which conflict with their custom namespace name.
Actually, that's interesting. Another possibility would be to only allow users to use names that we can promise we won't reuse. For example we could say `__x.+` is reserved for users, or something like that.

What we should really avoid is for someone to start using something like `__3`, which would conflict with something we want to use in the future. Even though it would be their problem in theory, in practice it might put pressure on us not to reuse the name (if it were an important vendor or something). Constraining what names they can use would clear this possibility out completely.


Repository:
  rCXX libc++

https://reviews.llvm.org/D53879