[cfe-dev] Removing InitHeaderSearch

[Edward Meewis]

Hi G M,

On 15/10/2013 22:56, G M wrote:
> Hi Edward
> On Wed, Oct 16, 2013 at 9:40 AM, Edward Meewis 
> <ed at extraordinarymachine.nl <mailto:ed at extraordinarymachine.nl>> wrote:
>
>     Hi,
>
>     I was looking into polishing up the header inclusion for FreeBSD,
>     due to some cmake build issues I have when building the the latest
>     libcxx with the latest clang.
>
> I'm curious what the cmake issues are.

I build clang ToT and libcxx with the previous clang-ToT, using the 
previous libcxx. Sometimes the introduction of new macros, e.g., 
_LIB_WEAK, breaks the build. The cause is subtle: I have to point CXX to 
-I/usr/local/include/c++/v1, but when libcxx is build this needs to be 
overridden to $MYLIBCXXLIB/include when libcxx is built. -nostdcxxinc is 
no help here, because I had to set it explicitly.
I can work around it by pointing the build to $MYLIBCXXLIB/include, but 
that's not very nice. New headers with old libraries usually spell disaster.

>
>     It seems that the InitHeaderSearch is almost obsolete, I think
>     that most of the header search path information has moved to the
>     Frontend/Tool(Chain)(s) files.
>
>     It turns out that (naively) removing InitHeaderSearc.cpp broke the
>     CPP init and consequently 'diagtool'.
>
> I think InitHeaderSearch is needed by mingw tool chain at least, 
> maybe others.  It could be cleaned up but the functionality is needed 
> for now.
>
>
>     Is it worth while to move CPP to the ToolChain infra?
>
> What does that mean in practice?

Don't know yet. I guess defining a mingw toolchain in ToolChains, that 
includes the necessary funtionality, but the miriad of MinGW versions 
scares me a bit.
>
> Thanks