[cfe-users] Building llvm/clang with another version of clang

[Edward Diener]

On 01/05/2013 01:18 PM, Dmitri Gribenko wrote:
> On Sat, Jan 5, 2013 at 7:58 PM, Edward Diener
> <eldlistmailingz at tropicsoft.com>  wrote:
>> On 01/05/2013 09:16 AM, Dmitri Gribenko wrote:
>>> On Sat, Jan 5, 2013 at 7:31 AM, Edward Diener
>>> <eldlistmailingz at tropicsoft.com>  wrote:
>>>> Is it possible to build llvm/clang with a previous version of clang
>>>> installed as a binary ? If so, how do I get llvm/configure to use the binary
>>>> version of clang rather than gcc to build the latest version of llvm/clang ?
>>>
>>> configure (but not CMake) will check for 'clang' in PATH and prefer to
>>> use it instead of 'gcc' or 'cc'.  So just ensure that the previous
>>> version of clang is in your PATH.
>>
>> Yes, I discovered this. This contradicts what LLVM has in its own
>> getting started page at
>> http://llvm.org/docs/GettingStarted.html#local-llvm-configuration.
>
> I have updated docs now.

Thanks !

>
>> Doesn't the clang 3.0 binaries ship with its own version of the C++ and
>> C header files ?
>
> No, clang does not include a complete standard library.  It does
> include a few system headers
> (clang-installation-dir/lib/clang/3.3/include), but that is not a
> complete standard library.

That is really a shame. Relying on some version of clang, whether built 
or distributed as a binary, working with whatever headers and libraries 
are used with the version of gcc installed does not seem a good way to 
do things to me. I sincerely hope that clang changes this.

I know it is a ton of work for clang to develop its own 
headers/libraries but I believe that each clang version should at least 
be distributed and/or built with a version of gcc's header/libraries 
with which it is guaranteed to work and that running clang will always 
use those correct headers/libraries no matter what headers/libraries a 
particular version of gcc comes with.