R devel - Apr 2019 - configure script issue with -flto with recent gcc and system ar/ranlib

Hi,

there can be an issue with recent gcc where the system-installed "ar"
and "ranlib" commands cannot handle LTO binaries.  On compilation,
this
manifests itself with error messages claiming that they need extra
plugins.

This can be fixed by using the command line

$ AR=gcc-ar RANLIB=gcc-ranlib ./configure --enable-lto

so it is not a big issue, but it would still be nicer if the configure
script tested the functionality of ar and ranlib itself and would
select the appropriate one accordingly.

This is with R version 3.5.3.

Regards

	Thomas

On 4/23/19 2:59 PM, Thomas K?nig wrote:
> Hi,
>
> there can be an issue with recent gcc where the system-installed
"ar"
> and "ranlib" commands cannot handle LTO binaries.? On
compilation, this
> manifests itself with error messages claiming that they need extra
> plugins.
>
> This can be fixed by using the command line
>
> $ AR=gcc-ar RANLIB=gcc-ranlib ./configure --enable-lto
>
> so it is not a big issue, but it would still be nicer if the configure
> script tested the functionality of ar and ranlib itself and would
> select the appropriate one accordingly.
>
> This is with R version 3.5.3.
Thanks for the report. What was the version of binutils on the system 
with this problem? On my Ubuntu 18.04 I can use the binutils version of 
"ar" and "ranlib" with --enable-lto without problems.? I
read that with
recent binutils (2.25?), the LTO plugin should be loaded automatically, 
so one does not have to use the wrappers anymore.

Thanks
Tomas
>
> Regards
>
> ????Thomas
>
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel

Hi Tomas,
> On 4/23/19 2:59 PM, Thomas K?nig wrote:
>> Hi,
>>
>> there can be an issue with recent gcc where the system-installed
"ar"
>> and "ranlib" commands cannot handle LTO binaries.? On
compilation, this
>> manifests itself with error messages claiming that they need extra
>> plugins.
> Thanks for the report. What was the version of binutils on the system 
> with this problem? On my Ubuntu 18.04 I can use the binutils version of 
> "ar" and "ranlib" with --enable-lto without problems.?
I read that with
> recent binutils (2.25?), the LTO plugin should be loaded automatically, 
> so one does not have to use the wrappers anymore.
This was with, on x86_64-pc-linux-gnu,

GNU ar (GNU Binutils; openSUSE Leap 42.3) 2.31.1.20180828-19

and, on powerpc64le-unknown-linux-gnu,

GNU ar version 2.27-34.base.el7

both with a recent gcc 9.0.1 snapshot.

Regards

	Thomas