[avr-libc-dev] device libs and spaces

[Georg-Johann Lay]

avr-gcc adds the new device specific libraries like dev/atmega8/devlib.a 
by means if lib_spec, which is defined in the device specific specs 
file.  Here an example for ATmega8:

*lib:
        -lc dev/atmega8/libdev.a%s

The "%s" makes the compiler driver to expand the argument to an absolute 
path provided the file can be found in multilib / startfile search paths 
and can be accessed.

This works as expected except in the case when the expanded path 
contains spaces.  The expanded path could escaped by an avr-specific 
spec function, however one level of escaping is not enough as lib_spec 
and its expansion is (re)used several times and passed around, e.g. by 
passthrough mechanisms of LTO compilations.  Escaping escaped sequences 
is not possible because the escape character will become a part of the 
path name then.

To make a long story short:

The current location for libdev.a is likely to cause problems when 
avr-gcc 5.0 hits user land, in particular windows where spaces in path 
names are not uncommon.

Consequently, a new device library naming convention is needed.  The 
simpliest solution would be to rename the device lib to "libatmega8.a" 
and place it in its multilib directory, i.e. what

$ avr-gcc -print-multi-directory -mmcu=atmega8

will print ("avr4" in that case).  With that naming convention lib_spec 
could be written as

*lib:
        -lc -latmega8

which works as expected.

Advantage of multilib directory is that it works exactly the same way if 
we should ever have more than one multilib per device, e.g. if we raise 
any ordinary option to a multilib option in the future.


Johann