From d635d6fd5027247ccd99573264e0fcd317e2455b Mon Sep 17 00:00:00 2001
From: Matthias Maier <tamiko@kyomu.43-1.org>
Date: Fri, 5 Apr 2013 08:47:44 +0000
Subject: [PATCH] CMake: Implement a sanity check for user supplied
 CMAKE_C_FLAGS and CMAKE_CXX_FLAGS

git-svn-id: https://svn.dealii.org/trunk@29197 0785d39b-7218-0410-832d-ea1e28bc413d
---
 deal.II/cmake/setup_cached_variables.cmake |  4 ++
 deal.II/cmake/setup_compiler_flags.cmake   | 46 ++++++++++++++++++++++
 deal.II/cmake/setup_external_macros.cmake  |  1 +
 3 files changed, 51 insertions(+)

diff --git a/deal.II/cmake/setup_cached_variables.cmake b/deal.II/cmake/setup_cached_variables.cmake
index f5c760bd7d..a86be64cf1 100644
--- a/deal.II/cmake/setup_cached_variables.cmake
+++ b/deal.II/cmake/setup_cached_variables.cmake
@@ -200,11 +200,15 @@ ENDFOREACH()
 SET_IF_EMPTY(CMAKE_C_FLAGS "$ENV{CFLAGS}")
 SET_IF_EMPTY(CMAKE_CXX_FLAGS "$ENV{CXXFLAGS}")
 SET_IF_EMPTY(CMAKE_SHARED_LINKER_FLAGS "$ENV{LDFLAGS}")
+UNSET(ENV{CFLAGS})
+UNSET(ENV{CXXFLAGS})
+UNSET(ENV{LDFLAGS})
 
 #
 # Set cached compiler flags to an empty string:
 #
 SET(DEAL_II_USED_FLAGS
+  CMAKE_C_FLAGS
   CMAKE_CXX_FLAGS
   DEAL_II_CXX_FLAGS_DEBUG
   DEAL_II_CXX_FLAGS_RELEASE
diff --git a/deal.II/cmake/setup_compiler_flags.cmake b/deal.II/cmake/setup_compiler_flags.cmake
index 80572fa7df..b8bbda6984 100644
--- a/deal.II/cmake/setup_compiler_flags.cmake
+++ b/deal.II/cmake/setup_compiler_flags.cmake
@@ -54,6 +54,46 @@
 #
 
 
+###########################################################################
+#                                                                         #
+#                             Sanity checks:                              #
+#                                                                         #
+###########################################################################
+
+#
+# Check the user provided C and CXX flags:
+# Only do this for CMAKE_C_FLAGS and CMAKE_CXX_FLAGS as this check is very
+# costly
+#
+SET(CMAKE_REQUIRED_FLAGS "${CMAKE_C_FLAGS_SAVED}")
+CHECK_C_SOURCE_COMPILES(
+  "int main(){ return 0; }"
+  DEAL_II_HAVE_USABLE_C_FLAGS)
+
+IF(NOT DEAL_II_HAVE_USABLE_C_FLAGS)
+  UNSET(DEAL_II_HAVE_USABLE_C_FLAGS CACHE)
+  MESSAGE(FATAL_ERROR "\n"
+    "Configuration error: Cannot compile with the specified C flags: "
+    "${CMAKE_C_FLAGS_SAVED}\n"
+    )
+ENDIF()
+UNSET(DEAL_II_HAVE_USABLE_C_FLAGS CACHE)
+
+SET(CMAKE_REQUIRED_FLAGS "${CMAKE_CXX_FLAGS_SAVED}")
+CHECK_CXX_SOURCE_COMPILES(
+  "int main(){ return 0; }"
+  DEAL_II_HAVE_USABLE_CXX_FLAGS)
+SET(CMAKE_REQUIRED_FLAGS "")
+
+IF(NOT DEAL_II_HAVE_USABLE_CXX_FLAGS)
+  UNSET(DEAL_II_HAVE_USABLE_CXX_FLAGS CACHE)
+  MESSAGE(FATAL_ERROR "\n"
+    "Configuration error: Cannot compile with the specified CXX flags: "
+    "${CMAKE_CXX_FLAGS_SAVED}\n"
+    )
+ENDIF()
+UNSET(DEAL_II_HAVE_USABLE_CXX_FLAGS CACHE)
+
 #
 # CMAKE_C_COMPILER and CMAKE_CXX_COMPILER have to be of the same brand.
 #
@@ -68,6 +108,12 @@ IF(NOT ( "${CMAKE_C_COMPILER_ID}" STREQUAL "${CMAKE_CXX_COMPILER_ID}" AND
 ENDIF()
 
 
+###########################################################################
+#                                                                         #
+#                            Compiler setup:                              #
+#                                                                         #
+###########################################################################
+
 IF(DEAL_II_SETUP_DEFAULT_COMPILER_FLAGS)
   #
   # *Hooray* We are allowed to set compiler flags :-]
diff --git a/deal.II/cmake/setup_external_macros.cmake b/deal.II/cmake/setup_external_macros.cmake
index 6adfecc7ab..f5c3a150a1 100644
--- a/deal.II/cmake/setup_external_macros.cmake
+++ b/deal.II/cmake/setup_external_macros.cmake
@@ -18,6 +18,7 @@
 
 INCLUDE(CheckCXXCompilerFlag)
 INCLUDE(CheckCXXSourceCompiles)
+INCLUDE(CheckCSourceCompiles)
 INCLUDE(CheckCXXSourceRuns)
 INCLUDE(CheckCXXSymbolExists)
 INCLUDE(CheckIncludeFileCXX)
-- 
2.39.5