[3.4] DESTDIR support completed

[Christian Cornelssen]

Hello,

On Sat, 11 Jan 2003, Gerald Pfeifer wrote:

> This needs to be reviewed by someone intimately familiar with the build
> system, but in any case, I am quite unhappy about "cluttering" the
> install documentation with something which the average user won't need.

Joseph Myers initially suggested documenting that feature (in
http://gcc.gnu.org/ml/gcc-patches/2002-03/msg01406.html).  I'd like
to hear about his view.  But hey, other doc maintainers are welcome
as well!  Please do not wait for each other :-)

> In other words, having this kind of documentation is very important,
> but the positition doesn't seem right -- the "default path" should
> be short and easy to follow, else the following paragraphs will be
> skipped/ignored by most users, I am afraid.

To give an overview, four paragraphs have been added
(see http://gcc.gnu.org/ml/gcc-patches/2003-01/msg00248.html):

(0) Mention that cross-compiler installations also install into
    tooldirs, if these exist.

(1) DESTDIR synopsis,

(2) Why relocations should use DESTDIR instead of prefix,

(3) What to care about when using DESTDIR in combination with tooldirs.

Originally, I just wanted to add a single paragraph (1) about DESTDIR,
but then I found that one of the more tricky parts of the system, namely
the handling of tooldirs (0), wasn't mentioned at all, although this
is relevant for non-DESTDIRed installations too.  Even in a "default path",
you have to inform the unsuspecting user about what will be installed.

Second, what's an "average" GCC installer?  One that faithfully su's
and runs "make install", without having tried to run the installation
such that no extra privileges are required and the outcome can be
examined easily?  I don't agree.

IMHO, the typical GCC installer is afraid of giving extra permissions
to an untested process.  Attempts to relocate the installation
directories for testing purposes can be assumed to be standard usage,
and using DESTDIR for that is preferable over changing prefix and all
the other configured installdirs.  Therefore, the documentation should
cover this (2) at a point where users can be expected to look for
detailed installation instructions.

Moreover, I estimate a fairly large part of GCC builders to use (or
like to use) packaging tools.  Typically, they are advanced enough to
favor systems that can not only install software, but also easily
replace them with more up-to-date versions, or uninstall them.
For packaging tools, the ability to relocate installation root
dirs, without changing the to-be-installed stuff, is essential,
and the DESTDIR feature has been designed to provide exactly this.
Hence, it is of wide interest, and should be described accordingly.

There is only one section "Final install" for detailed
installation instructions.  There is no such division as into
"GCC for beginners" and "GCC for power users".  I have inserted
the necessary documentation, which includes (3) for completeness,
at the only available place.  But we can create an own subsection
header for (1)..(3), so that DESTDIR-nonusers can easily skip it.
(This will require additional headers for the following subsections
too.)  What's your opinion about this?

Regards,

Christian Cornelssen