[PATCH] D19081: Add LLVMGetAttrKindIDInContext in the C API in order to facilitate migration away from LLVMAttribute

[Rafael Espíndola via llvm-commits]

> Note that name aren't more stable than ids in theory. in practice they are much more stable and it is possible for the function to return an error code on missing attribute name as suggested. by @whitequark .

I am fine with this as long as we document that an attribute name
might go away without the usual deprecation period that other C
visible features get.

Cheers,
Rafael