[CMake] Where to declare the CMAKE_C_FLAGS for cross compiling

[Martin Kupke]

I'm using a toolchain file with the CMAKE_SYSTEM_NAME "Generic", because 
I want to cross compile on a Windows XP machine for a PPC (PowerPC) 
processor. From my point of view it should be in a way as in the 
documentation for the SDCC.
My toolchain file "toolchain_ppc.cmake" is setup:
#############################################
set(CMAKE_SYSTEM_NAME "Generic")

if(CMAKE_CROSSCOMPILING)
message("Cross Compiling")
endif(CMAKE_CROSSCOMPILING)

# which compilers to use for C and C++
set(CMAKE_C_COMPILER "dcc.exe")
set(CMAKE_FIND_ROOT_PATH "C:/WindRiver/diab/5.9.0.0/WIN32/bin")
set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)

set(CMAKE_C_FLAGS "-tPPCVLEEN:simple")
#############################################

Additionally in the Platform folder I created a Generic-dcc file for 
system specific options:
#############################################
MESSAGE("SYSTEM_NAME=Generic")
set(CMAKE_C_FLAGS "-tPPCVLEEN:simple")
#############################################

In the windows console I call the CMake tool in an empty output folder:
D:\novero\Discovery\impl\target\CarIF_Appl\output>cmake -G "NMake 
Makefiles" -D CMAKE_TOOLCHAIN_FILE="..\toolchain_ppc.cmake" ..

The output of the CMake process shows that the test compilation could 
not be performed and the reason for that is, that my CMAKE_C_FLAGS are 
not passed to the configured compiler dcc.exe.
#############################################
Cross Compiling
-- The C compiler identification is unknown
-- The CXX compiler identification is unknown
SYSTEM_NAME=Generic
-- Check for working C compiler: c:/WindRiver/diab/5.9.0.0/WIN32/bin/dcc.exe
-- Check for working C compiler: 
c:/WindRiver/diab/5.9.0.0/WIN32/bin/dcc.exe --broken
CMake Error at C:/Program Files/CMake 
2.8/share/cmake-2.8/Modules/CMakeTestCCompiler.cmake:52 (MESSAGE):
   The C compiler "c:/WindRiver/diab/5.9.0.0/WIN32/bin/dcc.exe" is not 
able to compile a simple test program.

   It fails with the following output:
    Change Dir: 
D:/novero/Discovery/impl/target/CarIF_Appl/output/CMakeFiles/CMakeTmp
   Run Build Command:nmake /NOLOGO "cmTryCompileExec\fast"
         nmake -f CMakeFiles\cmTryCompileExec.dir\build.make /nologo -L
   CMakeFiles\cmTryCompileExec.dir\build

         "C:\Program Files\CMake 2.8\bin\cmake.exe" -E 
cmake_progress_report  
D:\novero\Discovery\impl\target\CarIF_Appl\output\CMakeFiles\CMakeTmp\CMakeFiles  
1

   Building C object CMakeFiles/cmTryCompileExec.dir/testCCompiler.c.obj

(LOOK_HERE)->        c:\WindRiver\diab\5.9.0.0\WIN32\bin\dcc.exe -o  
CMakeFiles\cmTryCompileExec.dir\testCCompiler.c.obj -c  
D:\novero\Discovery\impl\target\CarIF_Appl\output\CMakeFiles\CMakeTmp\testCCompiler.c

   Target Unknown.  Use the -t option or set a default target with dctrl -t

   NMAKE : fatal error U1077: 'C:\WINDOWS\system32\cmd.exe' : return 
code  '0x1'
   Stop.

   NMAKE : fatal error U1077: 'C:\WINDOWS\system32\cmd.exe' : return 
code  '0x2'
   Stop.

   CMake will not be able to correctly generate this project.
Call Stack (most recent call first):  CMakeLists.txt:2 (project)

CMake Error: your CXX compiler: "cl" was not found.   Please set 
CMAKE_CXX_COMPILER to a valid compiler path or name.
-- Configuring incomplete, errors occurred!
#############################################

I marked the position in the output with (LOOK_HERE)-> where you can see 
that the necessary compile flags  CMAKE_C_FLAGS "-tPPCVLEEN:simple" have 
not been passed to the compiler. Where do I have to declare the 
CMAKE_C_FLAGS?