From 9322babc082cf36559cdab8ded05dae4257d2999 Mon Sep 17 00:00:00 2001
From: "Joachim Wuttke (h)" <j.wuttke@fz-juelich.de>
Date: Wed, 22 Sep 2021 16:21:27 +0200
Subject: [PATCH] PreventInSourceBuilds.cmake: + header, for external use

---
 cmake/commons/PreventInSourceBuilds.cmake | 23 ++++++++++++++++++++++-
 1 file changed, 22 insertions(+), 1 deletion(-)

diff --git a/cmake/commons/PreventInSourceBuilds.cmake b/cmake/commons/PreventInSourceBuilds.cmake
index 37dc0d34231..31b20b107d7 100644
--- a/cmake/commons/PreventInSourceBuilds.cmake
+++ b/cmake/commons/PreventInSourceBuilds.cmake
@@ -1,4 +1,25 @@
-# - Prevent in-source builds.
+# PreventInSourceBuilds.cmake
+#
+# Forbids in-source builds.
+#
+# Rationale:
+# There is no good reason to run CMake from the main source directory,
+# as this would mess up the directory with compilation output.
+# If CMake is nonetheless run in-source, then this is most likely by accident.
+# This script is meant to prevent this specific accident.
+#
+# Usage:
+# Insert the line "include(PreventInSourceBuilds)" near the top
+# of the top-level CMakeLists.txt.
+#
+# License:
+# No rights reserved (CC0).
+#
+# Author:
+# Scientific Computing Group of JCNS-MLZ.
+#
+# Copyright:
+# Forschungszentrum Jülich GmbH 2021
 
 function(prevent_in_source_builds)
   # make sure the user doesn't play dirty with symlinks
-- 
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