Clear the previously determined TBB version if we need to revert to the bundled one.

diff --git a/cmake/configure/configure_1_threads.cmake b/cmake/configure/configure_1_threads.cmake
index 7cfe00dd43af97c9309d1077fcec82b310c0af69..6130e2e0b2841b0244b6de1377854c72ed1a66c6 100644 (file)
--- a/cmake/configure/configure_1_threads.cmake
+++ b/cmake/configure/configure_1_threads.cmake
@@ -146,6 +146,11 @@ MACRO(FEATURE_THREADS_FIND_EXTERNAL var)
   # versions:
   #
   IF(TBB_VERSION VERSION_LESS "4.2")
+    # Clear the previously determined version numbers to avoid confusion
+    SET(TBB_VERSION "bundled")
+    SET(TBB_VERSION_MAJOR "")
+    SET(TBB_VERSION_MINOR "")
+
     MESSAGE(STATUS
       "The externally provided TBB library is older than version 4.2.0, which "
       "cannot be used with deal.II."