[CMake] Include path Tcl under Cygwin

[Alan W. Irwin]

On 2013-07-04 10:35+0200 Arjen Markus wrote:

> On Thu, 4 Jul 2013 01:22:15 -0700 (PDT)
> "Alan W. Irwin" <irwin at beluga.phys.uvic.ca> wrote:
>> On 2013-07-04 09:54+0200 Arjen Markus wrote:
>>
>>>  As you can see, all is Cygwin-related, _except_ the
>>> path to the Tcl include files. I can assure you those
>>> files are present under /usr/include too, with all the
>>> ordinary permissions (-rw-r--r--) and for the correct
>>> version of Tcl (/usr/bin/tclsh returns 8.5.11 and the
>>> tcl.h file contains that very same version number).
>> 
>> Hi Arjen:
>> 
>> Set CMAKE_INCLUDE_PATH so that the cygwin version of the
>> headers is found.
>> 
>
> Using that option does force CMake to find the include files
> in the correct directory, but it should not be necessary
> to do that, should it?

In a perfect world (assuming there is a well understood set of
standard locations for Cygwin system files, that CMake knows about
those when you are running on the Cygwin platform, _and_ that CMake
searches those locations before it searches the "raw" Windows system
locations) you would be correct. However, if any of those assumptions
break down (which appears to be the case on your platform) then you
have to set CMAKE_INCLUDE_PATH (and CMAKE_LIBRARY_PATH) to give CMake
some guidance about where to look for headers and libraries beyond
whatever it assumes to be the standard system locations.

Don't feel too bad.  Even on Debian sometimes the CMake assumptions
about where to find stuff in standard system locations breaks down.
And in my particular case (lots of packages that I want to use that
are often not installed in standard system locations) I use
CMAKE_INCLUDE_PATH, CMAKE_LIBRARY_PATH, and PATH extensively to give
CMake some guidance for where it finds software.

Alan
__________________________
Alan W. Irwin

Astronomical research affiliation with Department of Physics and Astronomy,
University of Victoria (astrowww.phys.uvic.ca).

Programming affiliations with the FreeEOS equation-of-state
implementation for stellar interiors (freeeos.sf.net); the Time
Ephemerides project (timeephem.sf.net); PLplot scientific plotting
software package (plplot.sf.net); the libLASi project
(unifont.org/lasi); the Loads of Linux Links project (loll.sf.net);
and the Linux Brochure Project (lbproject.sf.net).
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