[PATCH] Fix move-if-change for VPATH builds

[Dmitry Shatrov]

I was visually inspecting the letter I've just sent and have found an
error in the patch (in binutils/Makefile.am, the "MOVE_IF_CHANGE ="
line). I'm surprised that this didn't pop up during compilation.

Sending the fixed patch. Please ignore the previous one, and sorry for
the inconvenience.


On Sun, 2007-12-23 at 01:13 +0300, Dmitry Shatrov wrote:
> Hello, binutils list!
> 
> I'm proposing a patch that fixes a problem I've had with building
> binutils-2.18. Building binutils-2.18 fails under the following
> conditions:
> 1. makeinfo is not installed
> 2. binutils are built in an external directory "binutils-build"
> 
> I am building it from an external directory because the "Linux From
> Scratch" book says that it is a recommended way of building binutils.
> 
> The build is failing because in binutils-2.18.tar.bz2 the timestamp of
> bfd/elf.c is greater than the timestamp of bfd/doc/elf.texi, so elf.texi
> is treated as requiring reubilding. As the result, bfd/doc/elf.texi gets
> reextracted from bfd/elf.c, and its timestamp becomes greater than the
> timestamp of bfd.texinfo. Building the latter fails, because makeinfo is
> missing.
> 
> This problem doesn't get triggered when building from the directory
> where binutils is unpacked, because there is the "move-if-change" script
> which determines that the newly extracted elf.tmp is actually the same
> as the present elf.texi, and thus the timestamp of elf.texi doesn't get
> changed. It turns out that the "move-if-change" script in its current
> form is inappropriate for VPATH builds: it doesn't break anything, but
> also doesn't help in situations it is meant to help.
> 
> What I suggest is making "move-if-change" aware of the directory where
> building is performed by passing "$(srcdir)" to it as the first
> argument. The only change in the algorithm is adding the following rule:
> "If the destination file "dstfile" is the same as the source file and
> the destination file doesn't exist in the current directory, then create
> a symbolic link "dstfile" pointing to "$(srcdir)/dstfile".
> 
> The rest of the patch is about making all invocations of
> "move-if-change" to supply "$(srcdir)" as the first argument.
> 
> The patch is against current binutils from CVS.
> 
> I've tested it for a while, with both texinfo installed and removed, for
> VPATH and non-VPATH builds, and for different combinations of timestamps
> on corresponding ".c", ".texi" and ".info" files, and it seems to work
> fine.
> 
> The patch includes changes to several "configure.ac" and "Makefile.am"
> files, but I didn't update corresponding "configure" and "Makefile.in"
> files before diff'ing, so autoconf and automake have to be invoked in
> all directories with the changed files after applying the patch.
> 
> Wbr,
> Dmitry
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