Created TEA architecture for fftw package, now TCL stubs library initialisation failure

I can configure, compile and run this tclfftw package (https://gitlab.com/teclabtcltk/tclfftw) unless I enable TCL stubs. Environment: Windows msys2 mingw64 Tcl86

As a workaround I had to do some nasty things:

configure.ac

if test "${TEA_PLATFORM}" = "windows" ; then
    # Use full Tcl DLL instead of stub library  
    TCL_LIB_FILE="libtcl86.dll.a"
    TCL_LIB_PATH="${TCL_BIN_DIR}/${TCL_LIB_FILE}"
    SHLIB_LD_LIBS="\${LIBS} \"`\${CYGPATH} \${TCL_LIB_PATH}`\" -static-libgcc"
    
    # Remove -static flag from LDFLAGS (keep -static-libgcc -static-libstdc++)
    LDFLAGS=`echo "$LDFLAGS" | sed 's/ -static$//'`
fi

Makefile.in

# Original DEFS from configure with stubs
DEFS_WITH_STUBS = @DEFS@ $(PKG_CFLAGS)
# Remove stubs defines for direct Tcl linking
DEFS        = $(filter-out -DUSE_TCL_STUBS=1 -DUSE_TCLOO_STUBS=1,$(DEFS_WITH_STUBS))

For simplicity I added the fftw3 library and header into a subfolder, so one can run:

autoconf
./configure --with-fftw3=./fftw
make
make install

All this works fine, and the tests also pass. However, as I already mentioned, when I use stubs, it fails with library initialisation failed.

I have some C code that works fine with stubs, but this C++ code does not. Perhaps someone has the patience to look into this and support me on this matter.

Solution

The answer from Donal is fully correct, but I had all those changes and it still was failing. What finally was missing, was the config.h.in file (See https://www.gnu.org/software/autoconf/manual/autoconf-2.69/html_node/autoheader-Invocation.html)

The configure.ac has this lines inside:

AC_CONFIG_HEADERS([config.h])

So the config.h gets generatated with the configure command. The .cpp file must include the config.h file, like:

...
#include "tcl.h"
#include "../config.h"
...

An then the build succeeded.

PS: Since I am not a C/CPP developer this whole build system is very hard to grasp for me. But today I learned a lot!