# Summary

xfwm4 (master git) compilation fails when configured as out-of-source build.

# Motivation

* Out-of-source build is highly desirable because source tree remains free of build artifact which, among other things, sometimes produce ill-effect.
* Among the benefits for the occasional contributor, it allows to efficiently grep in the source tree without seeing a lot of uninteresting hits in generated files.
* Others benefits of out-of-source build  are mentioned e.g. in http://voices.canonical.com/jussi.pakkanen/2013/04/16/why-you-should-consider-using-separate-build-directories/
* Out-of-source build has been supported in autoconf for a long time now, see for example this post from 2009: https://stackoverflow.com/questions/1311231/store-gnu-make-generated-files-elsewhere .

As shown below, one can have several build tree can be stored anywhere, not necessarily as a "build" subdir.  For example, one build tree per target architecture, or debug/test/optimized builds, etc, from the very same source tree.

# Symptom when compiling xfwm4

As shown by `make -k`, it appear that nearly everything builds right out-of-source, except fetching resources like svg icons.

Making all in common
make[2]: Entering directory '/.../xfwm4.buildtree/common'
make[2]: Nothing to be done for 'all'.
make[2]: Leaving directory '/.../xfwm4.buildtree/common'
Making all in settings-dialogs
make[2]: Entering directory '/.../xfwm4.buildtree/settings-dialogs'
  GEN      workspace-resource.h
/.../xfwm4/settings-dialogs/workspace.gresource.xml: Failed to locate ?monitor-icon.svg? in current directory.
Makefile:1025: recipe for target 'workspace-resource.h' failed
make[2]: *** [workspace-resource.h] Error 1
make[2]: Leaving directory '/.../xfwm4.buildtree/settings-dialogs'
Makefile:510: recipe for target 'all-recursive' failed
make[1]: *** [all-recursive] Error 1
make[1]: Leaving directory '/.../xfwm4.buildtree'
Makefile:442: recipe for target 'all' failed
make: *** [all] Error 2

# Additional information

Reproducible: always

* On same system, xfwm4 builds okay in-source, not out-of-source.
* On same system, tumbler (git clone https://git.xfce.org/xfce/tumbler) builds okay both in-source and out-of-source.

# Steps to reproduce:

The steps probably work on a vanilla Xubuntu system.  They successfully reproduce the issue here.

sudo apt-get build-dep xfce4-xfwm4 tumbler
sudo apt-get insall libwnck-3-dev
git clone http://git.xfce.org/xfce/xfwm4 ; cd xfwm4
git clean -dfx
export MYPREFIX="${PWD}.installtree"
(
export LC_ALL=C
set -eu
export SRCTREE="${PWD}"
export BUILDTREE="${PWD}.buildtree"
mkdir m4
NOCONFIGURE=indeed xdt-autogen
rm -rf "$BUILDTREE" "$MYPREFIX"
mkdir "$BUILDTREE" "$MYPREFIX"
cd "$BUILDTREE"
"${SRCTREE}"/configure --enable-maintainer-mode --prefix="${MYPREFIX?}" --enable-debug=yes
time make -j8 -k || time make
time make install && echo "BUILD SUCCESSFUL"
)

To test with tumbler, replace the git line with:

git clone https://git.xfce.org/xfce/tumbler ; cd tumbler


Thank you for your attention.


# Context information

Ubuntu 18.04 AMD64

Exact source tree reference for xfwm4: commit dc1610147ddfc77df40cf24c88c8083f24e531ef

Exact source tree reference for tumbler: commit 79b961a8520715fbd800c9def0632bc19569ecc1