CMake wrongly detects the host compiler for the host-tools when configuring a build

On my computer, I have the following compilers:

• MSVC (installed in C:\Program Files (x86)\Microsoft Visual Studio 10.0\...)
• MinGW (in C:\MinGW)
• Cygwin x86 and x64 (in C:\Cygwin and C:\Cygwin64)
• and of course, the RosBE toolkit (in C:\RosBE).

I have all those compilers because I need them for different reasons.
In order to reduce potential problems with ROS build configure, I removed from the system PATH environment all the instances of MinGW and Cygwin paths.

Now the problem: when I configure a ROS build with RosBE, CMake wrongly assumes I want to use cygwin for compiling the host-tools, and furthermore uses an non-existing compiler C:\Cygwin64\bin\cc, hence the configuration step completely fails. I'm wondering whether there is a clean way to bypass that, and to use instead what I would think is the correct host compiler, i.e. RosBE's gcc (at least, or fall down to MSVC in case I'm running the configuration in a VS command line, or within RosBE configured for MSVC).

In the meantime I elaborated a workaround that seems to work quite fine, see the patch below:

Index: configure.cmd

===================================================================

--- configure.cmd	(révision 68846)

+++ configure.cmd	(copie de travail)

@@ -187,7 +187,12 @@

     :: Launch new script instance for x86 host tools configuration

     start "Preparing host tools for ARM cross build..." /I /B /WAIT %~dp0configure.cmd arm_hosttools "%VSINSTALLDIR%VC\vcvarsall.bat" %CMAKE_GENERATOR_HOST%

 ) else (

-    cmake -G %CMAKE_GENERATOR% -DARCH:STRING=%ARCH% "%REACTOS_SOURCE_DIR%"

+    :: Hackfix!

+    if "%BUILD_ENVIRONMENT%" == "MinGW" (

+        cmake -G %CMAKE_GENERATOR% -DCMAKE_CROSSCOMPILING:STRING=FALSE -DCMAKE_TOOLCHAIN_FILE:FILEPATH=%MINGW_TOOCHAIN_FILE% -DARCH:STRING=%ARCH% "%REACTOS_SOURCE_DIR%"

+    ) else (

+        cmake -G %CMAKE_GENERATOR% -DCMAKE_CROSSCOMPILING:STRING=FALSE -DCMAKE_TOOLCHAIN_FILE:FILEPATH=toolchain-msvc.cmake -DARCH:STRING=%ARCH% "%REACTOS_SOURCE_DIR%"

+    )

 )

 cd..

EXPLANATIONS: to enforce the usage of the correct compiler for the host-tools, since on my computer the host-compiler and the cross-compiler are going to be the same, I explicitely specify the toolchain. However the toolchain file defines a CMake variable called CMAKE_SYSTEM_NAME,
which causes CMake to internally define the CMAKE_CROSSCOMPILING variable, and the host-tools configuration would fail. So, to bypass this other problem, I also enforce setting CMAKE_CROSSCOMPILING to FALSE for the host-tools only.

DISCLAIMER: This report is just here to think about the potential issues we can have using CMake.