[GRASSLIST:2236] Re: can't find tk.h

[Glynn Clements]

Richard Greenwood wrote:

> I am trying to build 5.0.3 on Cygwin, but configure is failing:
> 
>     checking for location of Tcl/Tk includes... /usr/local/include
>     checking for tcl.h... yes
>     checking for tk.h... no
> 
> But I have
>     --with-tcltk-includes=/usr/local/include
>  and  tk.h is in /usr/local/include !!!???
> 
> I think I am cross-eyed from looking at this for too long. What is it 
> that I am missing?

Look at config.log; that contains the commands which are being run and
their output (i.e. error messages).

Note that header checks involved attempting to preprocess a trivial
test program which includes the corresponding header (i.e. they don't
just check for the existence of a file). If any output is generated,
the test is deemed to have failed. A corollary of this is that
(otherwise) harmless warning messages will cause the test to fail.

Problems with the tk.h check are often related to the X headers. tk.h
includes X11/Xlib.h, which in turn includes several other X and system
headers. If any of those generate an error or warning message, the
check will fail.

If it turns out that the check *is* failing due to what should be a
harmless warning message, you can try using:

	CPPFLAGS=-w ./configure ...

to suppress warnings from the preprocessor. However, this should only
be done as a last resort, as it can obscure genuine problems. Also,
the -w switch should be removed manually from the COMPILE_FLAGS
setting in the src/CMD/head/head file once configure has completed.

-- 
Glynn Clements <glynn.clements at virgin.net>