powerpc/powerpc64 11.0-CURRENT not building clang by default: src.opt.mk not equivalent to 10.1-STABLE bsd.own.mk on the issue

[Mark Millard]

Nathan W. wrote:

> This is not the right one. That is related to clang 3.4. The issue is 
> that clang 3.5+ require a C++11 compiler to build. ...

The text that I quoted is from the 11.0-CURRENT UPDATING entry that starts with the non-FreeBSD-variant-specific 3.5.0 background information below. May be I originally should not have only extracted the material I thought fit best for being instructions for powerpc64 10.x: i.e., I should have given more context.

For future readers, quoting more UPDATING context this time...

> 20141231:
>         Clang, llvm and lldb have been upgraded to 3.5.0 release.
> 
>         As of this release, a prerequisite for building clang, llvm and lldb is
>         a C++11 capable compiler and C++11 standard library.  This means that to
>         be able to successfully build the cross-tools stage of buildworld, with
>         clang as the bootstrap compiler, your system compiler or cross compiler
>         should either be clang 3.3 or later, or gcc 4.8 or later, and your
>         system C++ library should be libc++, or libdstdc++ from gcc 4.8 or
>         later.


The later FreeBSD-variants-specific material makes for a complicated to read entry for powerpc/powerpc64 10.x. Why? Paragraph by paragraph for the next couple of paragraphs that follow the above...

>         On any standard FreeBSD 10.x or 11.x installation, where clang and
>         libc++ are on by default (that is, on x86 or arm), this should work out
>         of the box.

"where clang and libc++ are on by default": the libc++ part excludes powerpc/powerpc64 10.x. The 3.4.1 status for clang is not sufficient here, despite being after 3.3.

>         On 9.x installations where clang is enabled by default, e.g. on x86 and
>         powerpc, libc++ will not be enabled by default, so libc++ should be
>         built (with clang) and installed first.  If both clang and libc++ are
>         missing, build clang first, then use it to build libc++.

The "9.x" wording above makes no mention of 10.x but powerpc/powerpc64 10.x also has clang without having libc++ enabled by default. (Nor the libcxxrt that libc++ requires.) The instructions from here seem to be the ones that would apply (and likely do for powerpc64 --but not for powerpc as stands, see later).

After that is 8.x, Sparc64, and mips notes that are not a match to the powerpc/powerpc64 10.x context --and embedded system notes about cross builds:

>         On 8.x and earlier installations, upgrade to 9.x first, and then follow
>         the instructions for 9.x above.
> 
>         Sparc64 and mips users are unaffected, as they still use gcc 4.2.1 by
>         default, and do not build clang.
> 
>         Many embedded systems are resource constrained, and will not be able to
>         build clang in a reasonable time, or in some cases at all.  In those
>         cases, cross building bootable systems on amd64 is a workaround.

Taken literally no paragraph explicitly covers powerpc/powerpc64 10.x contexts for how to bootstrap to have clang present in 11.0-CURRENT.

By content the one starting with "On 9.x" is the closest match for powerpc/powerpc64 10.x.


My variant text with []'s might better have been:

        On 9.x installations where clang is enabled by default, e.g. on x86 and
        powerpc [10.x too], libc++ will not be enabled by default, so libc++ should be
        built (with clang) and installed first.  If both clang and libc++ are
        missing, build clang first, then use it to build libc++.

That would avoid odd implications for the combination x86 and 10.x by being explicitly localized to powerpc for the 10.x part.



But for powerpc (on-64) 10.1-STABLE even that adjustment would be wrong/incomplete...

powerpc 10.1-STABLE (3.4.1 clang present) does not build libcxxrt:

> ...
> building shared library libcxxrt.so.1
> /usr/bin/ld: warning: creating a DT_TEXTREL in a shared object.
> clang: error: linker command failed with exit code 1 (use -v to see invocation)
> *** Error code 1


That in turn means libc++'s build fails from the missing libcxxrt file that libc++'s build uses in its linking step.

That would make it rather hard to follow the instructions.

powerpc64 10.1-STABLE had no such problems building and installing those two libraries.

===
Mark Millard
markmi at dsl-only.net

On 2015-Mar-12, at 10:01 AM, Mark Millard <markmi at dsl-only.net> wrote:

Well there is an entry but when I read it I did not find it clear about the 10.x status.

I think the implication is that the 9.x paragraph also applies to 10.x:

       On 9.x [and 10.x] installations where clang is enabled by default, e.g. on x86 and
       powerpc, libc++ will not be enabled by default, so libc++ should be
       built (with clang) and installed first.  If both clang and libc++ are
       missing, build clang first, then use it to build libc++.

===
Mark Millard
markmi at dsl-only.net