[cfe-dev] Building clang with MingW and MSYS

[Óscar Fuentes]

Edward Diener <eldlistmailingz at tropicsoft.com>
writes:

>> The error is emitted after testing for the presence on the source tree
>> of the file
>>
>> include/llvm/Config/config.h
>>
>> That file is generated by the configure script of by cmake.
>>
>> Are you using the same sources you previously used for building with VS
>> in-source?'
>
> Yes.
>
>>  If yes, you must start from a clean source directory. Some
>> version control tools have commands for removing all unversioned files,
>> but I don't know about svn.
>
> Wow, this is a wonderful build system, that can not even build clang for 
> two different compilers without conflict. Is this CMake or just 'Nix 
> configure ? OK, it is useless to complain about such things but this is 
> very poor. Maybe LLVM and Clang should consider something better.

Please don't be so fast at reaching to conclusions. What you observed is
something perfectly reasonable. First, you used cmake for building
in-source. This creates several files mixed with the original source
files (in-source means exactly that and the configure script does the
same). Then you invoked the configure script from another
directory. That error message you got is preventing you from building on
a conflicting state, as the generated config.h and other files which are
mixed with the source code may be inadequate for the configuration of
your new build.

If you plan to build the same source code with different settings,
always do out-of-source builds.

[snip]