[llvm-dev] [LLVMdev] Ideas for making llvm-config --cxxflags more useful

Hans Wennborg via llvm-dev
Mon, 10 Aug 2015 20:34:32 -0000

On Sat, Aug 8, 2015 at 4:02 AM, David Chisnall via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
> On 7 Aug 2015, at 23:17, Tom Stellard via llvm-dev <llvm-dev at
lists.llvm.org> wrote:
>>
>> I don't have any strong opinions.  Did this actually break
anyone's use
>> case or is it just a hypothetical problem?  It doesn't seem like
there
>> is much value in fixing this until llvm-config is also fixed.
>
> The current 3.7 code breaks for the codebase that I use for teaching.  It
uses RTTI in the AST construction, so can’t be compiled with -fno-rtti, but does
need to use Module, IRBuilder, and friends, so not being able to link against an
LLVM that’s built without RTTI is annoying (it means that the students can’t use
LLVM packages on any OS).

This sounds pretty unfortunate, and if David is running into it then
others probably will too (and those users might find the errors more
confusing).

If this is possible to fix by adding anchor functions to the various
Instruction subclasses, that seems like a good fix (new functions is
probably better than adding out-of-line ctors/dtors).

In any case, to get such a fix merged to 3.7, the code owner would
need to approve it. I don't think there is a specific owner for the
IR, which means it falls under Chris's catch-all, so I'd like to hear
what he thinks.