Experiences with [cross-compiling] Tcl packages ...

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''[sbasi] 2016-05-29'': I successfully cross-compiled a Tcl extension from Linux for Windows.
I did it with cmake[http://www.cmake.org/] and MinGW-w64[http://mingw-w64.org/]. The only problem was that cmake did not find
the Tcl header files and libraries. Apart from that, it was actually surprisingly simple.

A little more detail:
   * The extension was already set up to be configured and compiled with cmake (see also [Cmake])
   * Needed tools: MinGW-w64, cmake
   * Also needed: Tcl header files and libraries for Windows. I got them from [https://bitbucket.org/tombert/tcltk/downloads%|%tombert's tcltk%|%], and saved them in /home/foo/crosscompile/
   * The next step was to create a toolchain file for cross-compilation:
===

# 
# Toolchain file to cross-compile for windows
#

# the name of the target operating system
SET(CMAKE_SYSTEM_NAME Windows)

# which compilers to use for C and C++
SET(CMAKE_C_COMPILER i686-w64-mingw32-cc)
SET(CMAKE_CXX_COMPILER i686-w64-mingw32-c++)

# here is the target environment located
SET(CMAKE_FIND_ROOT_PATH  /usr/i686-w64-mingw32)

# adjust the default behaviour of the FIND_XXX() commands:
# search headers and libraries in the target environment, search 
# programs in the host environment
set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)

# settings for Tcl/tk
# we need to set these variables manually, because cmake does not find them
set (TCL_INCLUDE_PATH /home/foo/crosscompile/include/)
set (TCL_STUB_LIBRARY /home/foo/crosscompile/lib/libtclstub86.a)
set (TK_INCLUDE_PATH /home/foo/crosscompile/include/)
set (TK_STUB_LIBRARY /home/foo/crosscompile/lib/libtkstub86.a)

===

   * Assuming the toolchain file is saved in /home/foo/crosscompile/toolchain.cmake, the extension can be compiled with:

===   

$ cmake -DCMAKE_TOOLCHAIN_FILE=/home/foo/crosscompile/toolchain.cmake ${path_to_source_dir}
$ make

===

To be noted that the only dependencies of the extension in question were the standard C library and Tcl/Tk. With more deps, things might get a little harder.

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