AC_RUN_IFELSE and crosscompiling (was: Tinderbox failure, Android-ARM at 86-TDF, MASTER, last success: 2020-09-07 19:23:07)

[Stephan Bergmann]

On 09/09/2020 16:25, lohmaier+tinderbox at gmail.com wrote:
> One of you broke the build of LibreOffice with your commit :-(
> Please commit and push a fix ASAP!
> 
> Full log available at http://tinderbox.libreoffice.org/MASTER/status.html
> 
>   Tinderbox info:
> 
>   Box name: Android-ARM at 86-TDF
>   Branch: master
>   "starttime": 1599661339
>   Machine: Linux vm216.documentfoundation.org 3.10.0-1127.18.2.el7.x86_64 #1 SMP Sun Jul 26 15:27:06 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
>   Configured with: --with-distro=LibreOfficeAndroid
> --with-build-platform-configure-options=--without-system-libxml
> --with-android-sdk=/tinderbox/buildslave/android
> --with-android-ndk=/tinderbox/buildslave/android/ndk/20.1.5948944
> --with-external-tar=/home/buildslave/source/lo-externalsrc
> --with-jdk-home=/etc/alternatives/java_sdk_11
> --enable-android-editing
> 
>   Commits since the last success:
> 
>   ==== core ====
[...]
>    ad6ef81  Guard against some GCC consteval bug
[...]
> 
>   The error is:
> 
>   autogen/configure failed - error is::
> 
> ======
> Running ./configure with '--host=arm-linux-androideabi --disable-cairo-canvas --disable-cups --disable-gstreamer-1-0 --disable-randr --without-export-validation --without-helppack-integration --without-junit --disable-largefile --with-theme=colibre --with-build-platform-configure-options=--without-system-libxml --with-android-sdk=/tinderbox/buildslave/android --with-android-ndk=/tinderbox/buildslave/android/ndk/20.1.5948944 --with-external-tar=/home/buildslave/source/lo-externalsrc --with-jdk-home=/etc/alternatives/java_sdk_11 --enable-android-editing --srcdir=/tinderbox/buildslave/source/libo-master --enable-option-checking=fatal'
> ********************************************************************
> *
> *   Running LibreOffice build configuration.
> *
> ********************************************************************
> 
[...]
> checking whether ccache clang++ supports a working C++20 consteval... configure: error: in `/tinderbox/buildslave/build':
> configure: error: cannot run test program while cross compiling
> See `config.log' for more details
> Error running configure at /tinderbox/buildslave/source/libo-master/autogen.sh line 299.

Re 
<https://git.libreoffice.org/core/+/ad6ef813e9d745d44719dae381d64cdcc2f82719%5E!> 
"Guard against some GCC consteval bug" using RC_RUN_IFELSE in 
configure.ac, what is the general approach to that in cross compilation 
builds like the Android ones?

There are various pre-existing uses of RC_RUN_IFELSE that apparently did 
not run into this issue, presumably because they happen to be behind 
some conditions that happen not to be true for any cross compilation builds?