[PATCH 2/2] add example how to use derived sbuild chroots

[Felix Moessbauer <felix.moessbauer@siemens.com>]

This patch extends the samefile recipe to use a derived sbuild chroot to
compile the tool using clang instead of gcc. While there are easier ways
to achive this goal, it is still valuable to demonstrate how to use the
infrastructure.

Signed-off-by: Felix Moessbauer <felix.moessbauer@siemens.com>
---
 meta-isar/recipes-app/samefile/samefile_2.14.bb       |  8 ++++++++
 .../sbuild-chroot/sbuild-chroot-target-clang.bb       | 11 +++++++++++
 2 files changed, 19 insertions(+)
 create mode 100644 meta-isar/recipes-devtools/sbuild-chroot/sbuild-chroot-target-clang.bb

diff --git a/meta-isar/recipes-app/samefile/samefile_2.14.bb b/meta-isar/recipes-app/samefile/samefile_2.14.bb
index c53c9445..989e1983 100644
--- a/meta-isar/recipes-app/samefile/samefile_2.14.bb
+++ b/meta-isar/recipes-app/samefile/samefile_2.14.bb
@@ -5,6 +5,9 @@
 
 inherit dpkg
 
+# for demo reasons, we compile with clang if not cross-compiling
+SBUILD_FLAVOR = "${@ 'clang' if d.getVar('ISAR_CROSS_COMPILE') != '1' else '' }"
+
 DEBIAN_DEPENDS = "\${misc:Depends}"
 DESCRIPTION = "utility that finds files with identical contents"
 
@@ -42,4 +45,9 @@ EOF
 
     # We can also customize afterwards, in this case change the package section.
     sed -i -e 's/Section: misc/Section: utils/g' ${S}/debian/control
+
+    # use clang to compile (no cross support yet)
+    if [ "${SBUILD_FLAVOR}" = "clang" ]; then
+        sed -i -e 's/\(#\!.*\)/\1\nexport CC=clang/g' ${S}/debian/rules
+    fi
 }
diff --git a/meta-isar/recipes-devtools/sbuild-chroot/sbuild-chroot-target-clang.bb b/meta-isar/recipes-devtools/sbuild-chroot/sbuild-chroot-target-clang.bb
new file mode 100644
index 00000000..3df16368
--- /dev/null
+++ b/meta-isar/recipes-devtools/sbuild-chroot/sbuild-chroot-target-clang.bb
@@ -0,0 +1,11 @@
+# Root filesystem for packages building with clang
+#
+# This software is a part of ISAR.
+# Copyright (C) 2023 Siemens AG
+
+DESCRIPTION = "Isar sbuild/schroot filesystem for target (clang variant)"
+
+require recipes-devtools/sbuild-chroot/sbuild-chroot-target.bb
+
+SBUILD_FLAVOR = "clang"
+SBUILD_CHROOT_PREINSTALL_COMMON += "clang"
-- 
2.34.1