[LLVMdev] 3.4 branch gcc 4.9 build error

[Tom Stellard]

On Thu, May 15, 2014 at 10:41:08PM +0300, Alp Toker wrote:
> 
> On 15/05/2014 22:12, Tom Stellard wrote:
> >On Thu, May 15, 2014 at 01:38:32PM +0200, Tuncer Ayaz wrote:
> >>On Thu, 15 May 2014 02:25:30 +0200, Tom Stellard wrote:
> >>
> >>>On Sat, May 10, 2014 at 11:48:23PM +0200, Tuncer Ayaz wrote:
> >>>>Tom,
> >>>>
> >>>>now that 3.4.1 is out, any chance of a 3.4.2 with just the three
> >>>>fixes or at least merging them to the 3.4 branch?
> >>>I've pushed the two approved patches to the 3.4 branch, can you
> >>>verify that they work with gcc 4.9.
> >>Thanks, Tom.
> >>
> >>Fresh (svn rev 208853) checkout of llvm, clang, etc:
> >>
> >>llvm[1]: Compiling APFloat.cpp for Release build
> >>In file included from APFloat.cpp:15:
> >>In file included from /tmp/llvm/include/llvm/ADT/APFloat.h:20:
> >>In file included from /tmp/llvm/include/llvm/ADT/APInt.h:19:
> >>In file included from /tmp/llvm/include/llvm/ADT/ArrayRef.h:14:
> >>In file included from /tmp/llvm/include/llvm/ADT/SmallVector.h:17:
> >>In file included from /tmp/llvm/include/llvm/Support/AlignOf.h:19:
> >>/usr/lib64/[...]/c++/4.9.0/cstddef:51:11: error:
> >>       no member named 'max_align_t' in the global namespace
> >>   using ::max_align_t;
> >>         ~~^
> >>1 error generated.
> >>
> >Is this trunk or the 3.4 branch?
> >
> >>As the fixes got merged to the release_34 branch, I went to check the
> >>local configure options and noticed I was passing --enable-cxx11. If I
> >>omit that, there's no max_align_t error. I don't remember when I added
> >>that, but it used to build prior to gcc 4.9. Just so I understand, is
> >>that flag meant to be enabled (and known to work) when llvm is built
> >>by clang, or is that also in need of fixing for gcc 4.9?
> >So clang/llvm will only fail to build with gcc 4.9 if the --enable-cxx11 flag is used?
> 
> The underlying problem was that, without the fix, clang's C++11 mode
> didn't work *at all* with system headers shipped by GCC 4.9.
> 
> So the failure to self-host with --enable-cxx11 mentioned by Tuncer
> is really only a secondary symptom of the wider problem reported by
> distributions.
> 

So does this mean there is an additional fix that is required for the 3.4 branch?

-Tom

> Alp.
> 
> 
> >
> >-Tom
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