[Ecls-list] ecl include and library directories

[Nils Bruin]

I am having some trouble with figuring out the default choices of the 
values of some of the paths used by the ECL compiler.

I have a fairly vanilla install of ecl, where I think that at least the 
relative positions of the installed files concerning ecl are typical. I 
find:

> (translate-logical-pathname "SYS:")
#P"/mnt/usb1/scratch/nbruin/4.6.2/local/lib/ecl/"
> (require 'cmp)
;;; Loading #P"/mnt/usb1/scratch/nbruin/4.6.2/local/lib/ecl/cmp.fas"
("CMP")
> c::*ecl-library-directory*
"/mnt/usb1/scratch/nbruin/4.6.2/local/lib/"
> (c::ecl-library-directory)
"/mnt/usb1/scratch/nbruin/4.6.2/local/lib/"

This indicates that the value of c::*ecl-library-directory* was vetted and 
found correct. This was done by the test:

   (probe-file (merge-pathnames (compile-file-pathname "ecl" :type
                                             #+dlopen :shared-library
                                             #-dlopen :static-library)
                                            c::*ecl-library-directory*))

which succeeds with

#P"/mnt/usb1/scratch/nbruin/4.6.2/local/lib/libecl.so.11.1.1"

However, if I do

> (setf c::*ecl-library-directory* nil)
> (c::ecl-library-directory)
"/mnt/usb1/scratch/nbruin/4.6.2/local/lib/ecl/"
> c::*ecl-library-directory*
"/mnt/usb1/scratch/nbruin/4.6.2/local/lib/ecl/"

I see the system has cooked up another default, namely the directory for 
which (probe-file "SYS:BUILD-STAMP") succeeds. However, the file libecl.so 
does not reside there!

This means that c::ecl-library-directory, when presented with a value of 
c::*ecl-library-directory* it thinks is invalid, overwrites it with a 
value that is also invalid by its earlier criterion! That's probably not 
as intended.

Shouldn't the value be initialized to the following ?

(namestring (make-pathname :directory (butlast (pathname-directory
                               (translate-logical-pathname "SYS:")))))

A similar story applies to cc:ecl-include-directory:
> (c::ecl-include-directory)
"/mnt/usb1/scratch/nbruin/4.6.2/local/include/"

which was approved because the following succeeds:

> (probe-file (merge-pathnames "ecl/config.h" c::*ecl-include-directory*))
#P"/mnt/usb1/scratch/nbruin/4.6.2/local/include/ecl/config.h"

Should that fail, then the routine tries if "SYS:" would be a reasonable 
candidate via

> (probe-file "SYS:ecl;config.h")
NIL

I don't think that will succeed in any sane installation. The value that 
would probably be OK is "SYS:..;..;include", given that:

> (probe-file "SYS:..;..;include;ecl;config.h")
#P"/mnt/usb1/scratch/nbruin/4.6.2/local/lib/ecl-11.1.1/../../include/ecl/config.h"

so probably the thing to try would be:

(namestring (make-pathname :directory (append (butlast (pathname-directory 
(translate-logical-pathname "SYS:")) 2) '("include"))))

Most of this doesn't normally matter because ECL captures reasonable 
default values for *ecl-library-directory* and *ecl-include-directory* at 
build-time.

However, would you be interested in using reasonable defaults derived from 
runtime information (being "SYS:") instead? It would mean that ECL 
continues to work if its installation is moved after build, as long as the 
relative position of headers and libraries is as usual.

Best wishes,

Nils