[LLVMdev] Explicit template instantiations in libc++

[Sean Silva]

Given the dates, this seems unrelated, but there have been compile-time
issues with libc++ for some time now:
http://llvm.org/bugs/show_bug.cgi?id=14587

-- Sean Silva


On Tue, Aug 12, 2014 at 2:17 PM, Justin Bogner <mail at justinbogner.com>
wrote:

> Most of libc++ doesn't have explicit template instantiations, which
> leads to a pretty significant build time and code size cost when using
> libc++, since a large number of common templates will be emitted by the
> compiler and coalesced by the linker. Notably, in include/__config, we
> have:
>
>     #ifndef _LIBCPP_EXTERN_TEMPLATE
>     #define _LIBCPP_EXTERN_TEMPLATE(...)
>     #endif
>
> whereas before r189601 this was:
>
>     #define _LIBCPP_EXTERN_TEMPLATE(...) extern template __VA_ARGS__;
>
> This was apparently done to fix http://llvm.org/bugs/show_bug.cgi?id=17027
> ,
> but disabling explicit instantiations seems like a pretty big hammer
> considering the drawbacks.
>
> I'd like to restore these instantiations. Any thoughts on how to handle
> things like pr17027 in a less heavy handed way?
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