[PATCH] Shorter object file names under subdir-objects

[Thomas Martitz]

Mathieu, based on your reaction on the other thread, I reworked my patch.

This supersedes my other patch, "[PATCH] new option: object-shortname". 
It is functionally the
same but does not introduce a new option, but ties the behavior to 
subdir-objects instead. In
addition I made an additional bug fix and extended the test suite.

Please merge.
Commit message follows:

With the %reldir% feature, object file names can become very long, 
because the file names
are prefixed with the %canon_reldir% substitution. The reason is to 
achieve unique object
file names when target-specific CFLAGS or similar are used. When 
subdir-objects is also
in effect, these long file names are also placed in potentially deep 
subdirectories.

But with subdir-objects this is unecessary, since uniqueness of the 
object file names
is already achieved by placing them next to the unique source files.

Therefore, this changes strips paths components, that are caused by 
%canon_reldir% or
otherwise, from the object file names. The object file name is prefixed 
by the target in
case of target-specific CFLAGS. As a result, the build tree looks less 
scary and many
cases where $var_SHORTNAME was necessary can now be avoided. Remember 
that the use of
$var_SHORTNAME is discouraged (and is not always an option since it does 
not work inside
conditionals).

Example:
previously:
    sub/Makefile.am:
    AUTOMAKE_OPTIONS = subdir-objects
    bin_PROGRAMS += %D%/foo
    %C%_foo_CFLAGS = $(AM_CFLAGS) -g

resulted in objects:
    sub/sub_foo-foo.o

now object file name is:
    sub/foo-foo.o

0001-Shorter-object-file-names-under-subdir-objects.patch
Description: Source code patch