[Mesa-dev] Build fail since configure.ac: rework llvm libs handling for 3.9+

[Andy Furniss]

Michel Dänzer wrote:
> On 18/10/17 05:41 PM, Emil Velikov wrote:
>> On 17 October 2017 at 15:39, Andy Furniss <adf.lists at gmail.com>
>> wrote:
>>> Emil Velikov wrote:
>>> 
>>>>>> On a "bad" build (-DLLVM_BUILD_LLVM_DYLIB=ON) I get
>>>>>> 
>>>>>> andy [~]$ llvm-config --link-shared --libs bitwriter 
>>>>>> llvm-config: error: missing: /usr/lib/libLLVMDemangle.so 
>>>>>> llvm-config: error: missing: /usr/lib/libLLVMSupport.so 
>>>>>> llvm-config: error: missing:
>>>>>> /usr/lib/libLLVMBinaryFormat.so llvm-config: error:
>>>>>> missing: /usr/lib/libLLVMCore.so llvm-config: error:
>>>>>> missing: /usr/lib/libLLVMBitReader.so llvm-config: error:
>>>>>> missing: /usr/lib/libLLVMMC.so llvm-config: error: missing:
>>>>>> /usr/lib/libLLVMMCParser.so llvm-config: error: missing:
>>>>>> /usr/lib/libLLVMObject.so llvm-config: error: missing:
>>>>>> /usr/lib/libLLVMProfileData.so llvm-config: error: missing:
>>>>>> /usr/lib/libLLVMAnalysis.so llvm-config: error: missing:
>>>>>> /usr/lib/libLLVMBitWriter.so
>>>> 
>>>> 
>>>> These here indicate that something in LLVM broke. Please report
>>>> it ASAP so that we don't get a LLVM release with this bug.
>>> 
>>> 
>>> https://bugs.llvm.org/show_bug.cgi?id=34977
>>> 
>> Great, thank you. In the interim please use the
>> LLVM_LINK_LLVM_DYLIB workaround. Just checked LLVM 5.0 w/o
>> LLVM_LINK_LLVM_DYLIB - seems to also be broken in the same way.
>> 
>> Considering distributions (checked Fedora, Arch, Ubuntu and
>> Debian) toggle both BUILD and LINK together, I'm inclined to keep
>> things as-is.
> 
> Right, I'd recommend enabling LLVM_LINK_LLVM_DYLIB anyway when 
> LLVM_BUILD_LLVM_DYLIB is enabled. Is there any particular reason for 
> enabling the latter but not the former?

No idea from a technical POV.

As a user, when cmake became mandatory, looking at the cmake docs
there is option BUILD_SHARED_LIBS - but it is noted not to use this

"BUILD_SHARED_LIBS is only recommended for use by LLVM developers. If
you want to build LLVM as a shared library, you should use the
LLVM_BUILD_LLVM_DYLIB option."

I also notice that blfs use LLVM_BUILD_LLVM_DYLIB

http://www.linuxfromscratch.org/blfs/view/systemd/general/llvm.html