Re: make dist-lzma and make dist-xz

[Stefano Lattarini]

oOn Monday 12 December 2011, Peter Rosin wrote:
> Hi!
>
Hi Peter.

> I noticed that the changes to "make dist-xz" to default to -e fixed
> the xz.test on MinGW, but that lzma.test still fails (lzma: (stdin): Not
> enough memory).
>
[BTW: thanks for your continuous testing with Cygwin and MinGW!]

> Hoping to fix the last fail in the testsuite, I looked
> into adding something like LZMA_OPT or something to "make dist-lzma".
> But in my cursory googling, I could not get my grips around what variable
> to use. Does anyone know?
>
I don't, but I have another consideration: since lzma seems to be supersed
by xz [1][2], couldn't we simply deprecate the `dist-lzma' option in this
11.1.2 version, and remove it altogether from the next major (or even minor)
version?  WDYT?

[1] http://tukaani.org/lzma/
    says:
    "LZMA Utils are legacy data compression software with high compression
     ratio. LZMA Utils are no longer developed, ...  Users of LZMA Utils
     should move to XZ Utils."

 [2] 
http://www.gnu.org/software/automake/manual/html_node/The-Types-of-Distributions.html
     says:
     "dist-xz
      Generate an `xz' tar archive of the distribution. xz archives are
      frequently smaller than bzip2-compressed archives. The `xz' format
      will soon (early 2009) displace the ‘lzma’ format"

> However, what I did find was that there is a variable named XZ_DEFAULT.
> Shouldn't that be considered before "forcing" -e when XZ_OPT is missing?
>
From the xz manpage:

  XZ_DEFAULTS
    User-specific  or  system-wide default options.  Typically this is
    set in a shell initialization script to enable xz's memory usage
    limiter by default.  Excluding shell initialization scripts and
    similar special cases, scripts must never set or unset XZ_DEFAULTS.

So XZ_DEFAULTS is mostly meant to allow the user to set default memory
usage limiters; since we don't touch such a setting in our use of
XZ_OPT, I say we should be pretty safe.  Moreover:

  XZ_OPT
    This is for passing options to xz when it is not possible to
    set the options directly on the xz command line ...
    Scripts may use XZ_OPT e.g. to set script-specific default
    compression options.  It is still recommended to allow users
    to override XZ_OPT if that is reasonable ...

and our use of XZ_OPT seems consistent with the advice given here.

Regards,
  Stefano