From 44a638dce32b1368eb7a4b7940f1cc7b0fd9d972 Mon Sep 17 00:00:00 2001
From: Roland Kaufmann <roland.kaufmann@uni.no>
Date: Wed, 13 Mar 2013 11:20:28 +0100
Subject: [PATCH] Test strings on length before content

A substring can of course not be longer that the full string. Also fixes
problems with CMake-versions that doesn't handle out-of-range parameters
to the SUBSTRING sub-command.
---
 cmake/Modules/DuneCompat.cmake | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/cmake/Modules/DuneCompat.cmake b/cmake/Modules/DuneCompat.cmake
index a9cd6884..e371c832 100644
--- a/cmake/Modules/DuneCompat.cmake
+++ b/cmake/Modules/DuneCompat.cmake
@@ -29,9 +29,19 @@ endif (CMAKE_GENERATOR MATCHES "Unix Makefiles")
 # source dir and most likely doesn't contain other projects) anyway,
 # i.e. we only copy if we are truly out-of-source
 string (LENGTH "${PROJECT_SOURCE_DIR}/" _src_dir_len)
-string (SUBSTRING "${PROJECT_BINARY_DIR}/" 0 ${_src_dir_len} _proj_prefix)
-if (NOT "${PROJECT_SOURCE_DIR}/" STREQUAL "${_proj_prefix}")
+string (LENGTH "${PROJECT_BINARY_DIR}/" _bin_dir_len)
+if (_src_dir_len GREATER _bin_dir_len)
+  set (_not_substring TRUE)
+else (_src_dir_len GREATER _bin_dir_len)
+  string (SUBSTRING "${PROJECT_BINARY_DIR}/" 0 ${_src_dir_len} _proj_prefix)
+  if ("${PROJECT_SOURCE_DIR}/" STREQUAL "${_proj_prefix}")
+	set (_not_substring FALSE)
+  else ("${PROJECT_SOURCE_DIR}/" STREQUAL "${_proj_prefix}")
+	set (_not_substring TRUE)
+  endif ("${PROJECT_SOURCE_DIR}/" STREQUAL "${_proj_prefix}")
+endif (_src_dir_len GREATER _bin_dir_len)
+if (_not_substring)
   execute_process (COMMAND
 	${CMAKE_COMMAND} -E copy_if_different ${PROJECT_SOURCE_DIR}/dune.module ${PROJECT_BINARY_DIR}/dune.module
 	)
-endif (NOT "${PROJECT_SOURCE_DIR}/" STREQUAL "${_proj_prefix}")
+endif (_not_substring)