From: Isuru Fernando <idf2@illinois.edu>
Date: Fri, 19 Apr 2019 00:35:43 +0000 (-0500)
Subject: CMake: Clear CMAKE_REQUIRED_FLAGS before calling FindLAPACK
X-Git-Tag: v9.1.0-rc1~196^2
X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=refs%2Fpull%2F7938%2Fhead;p=dealii.git

CMake: Clear CMAKE_REQUIRED_FLAGS before calling FindLAPACK

CMAKE_REQUIRED_FLAGS is populated by dealii with CXXFLAGS and this
should be cleared before calling any function that calls try_compile
on a C file. FindLAPACK calls FindTHREADS.cmake which uses try_compile
on a C file.
---

diff --git a/cmake/configure/configure_1_lapack.cmake b/cmake/configure/configure_1_lapack.cmake
index 2eb4519a15..b773ccbb8d 100644
--- a/cmake/configure/configure_1_lapack.cmake
+++ b/cmake/configure/configure_1_lapack.cmake
@@ -18,6 +18,7 @@
 #
 
 MACRO(FEATURE_LAPACK_FIND_EXTERNAL var)
+  CLEAR_CMAKE_REQUIRED()
   FIND_PACKAGE(LAPACK)
 
   #