[LLVMdev] Building llvm from source with clang instead of gcc

[Justin Holewinski]

On Sat, Jan 5, 2013 at 5:59 PM, Edward Diener <
eldlistmailingz at tropicsoft.com> wrote:

> On 01/05/2013 01:11 PM, Dmitri Gribenko wrote:
>
>> On Sat, Jan 5, 2013 at 7:48 PM, Edward Diener
>> <eldlistmailingz at tropicsoft.**com <eldlistmailingz at tropicsoft.com>>
>>  wrote:
>>
>>> I actually found out that llvm/configure will choose clang if it is
>>> found in the path. This contradicts what is written at
>>> http://llvm.org/docs/**GettingStarted.html#**requirements<http://llvm.org/docs/GettingStarted.html#requirements>,
>>> where it says it
>>> will use the first GCC it finds. Perhaps that explanation needs to be
>>> updated.
>>>
>>
>> Updated docs in r171630.
>>
>>  Finally I found that if llvm/configure uses clang instead of gcc, it
>>> invariably fails on my Linux distros because it is using the gcc
>>> distributed included directories and an earlier version of clang will
>>> often fail with these gcc header files. Once I force llvm/configure to
>>> use gcc, building llvm/clang succeeds again.
>>>
>>
>> Right.  Maybe we need to skip old clang versions in this case.
>>
>
> I think this should be done until clang can use its own header files and
> libraries, when it is installed as a binary, rather than the ones that gcc
> installs. In fact I am a bit amazed that clang does not already have its
> own header files and libraries for use when one tries llvm/configure and it
> sets up llvm's build system to use clang as its compiler. Is this the fault
> of clang or is it the fault of the llvm/configure system ?


There is no complete solution for LLVM-only headers/libraries yet on Linux.
 For C++, you can use libc++, but you still need some GCC libraries (or
alternatives).  And you will at least need glibc or another compatible C
runtime.


>
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-- 

Thanks,

Justin Holewinski
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