4.5.2 doesn't build due to wrong jar-usage (gcj)

[Oliver Kullmann <O dot Kullmann at swansea dot ac dot uk>]

Hello,

trying to build gcj with gcc version 4.5.2 I get the build error

checking for i686-pc-linux-gnu-ar... ar
checking for i686-pc-linux-gnu-ranlib... ranlib
checking for i686-pc-linux-gnu-dlltool... dlltool
checking for gawk... (cached) gawk
checking for jar... jar
checking for zip... no
checking for unzip... /usr/bin/unzip
Illegal option: @
Usage: jar {ctxui}[vfm0Me] [jar-file] [manifest-file] [entry-point] [-C dir] files ...
Options:
    -c  create new archive
    -t  list table of contents for archive
    -x  extract named (or all) files from archive
    -u  update existing archive
    -v  generate verbose output on standard output
    -f  specify archive file name
    -m  include manifest information from specified manifest file
    -e  specify application entry point for stand-alone application
        bundled into an executable jar file
    -0  store only; use no ZIP compression
    -M  do not create a manifest file for the entries
    -i  generate index information for the specified jar files
    -C  change to the specified directory and include the following file
If any file is a directory then it is processed recursively.
The manifest file name, the archive file name and the entry point name are
specified in the same order as the 'm', 'f' and 'e' flags.

Example 1: to archive two class files into an archive called classes.jar:
       jar cvf classes.jar Foo.class Bar.class
Example 2: use an existing manifest file 'mymanifest' and archive all the
           files in the foo/ directory into 'classes.jar':
       jar cvfm classes.jar mymanifest -C foo/ .

configure: error: cannot find neither zip nor jar, cannot continue
make[2]: *** [configure-target-libjava] Error 1
make[2]: Leaving directory `/compsci/saturn/staff/csoliver/OKplatform/ExternalSources/builds/Gcc/gcc-4.5.2_build'
make[1]: *** [all] Error 2
make[1]: Leaving directory `/compsci/saturn/staff/csoliver/OKplatform/ExternalSources/builds/Gcc/gcc-4.5.2_build'
make: *** [gcc] Error 1
make: Leaving directory `/compsci/saturn/staff/csoliver/OKplatform/ExternalSources'

jar exists (also unzip, but not zip), however it thinks it is wrongly used?
The requirements page of gcc only says that "jar or zip" is needed, and nothing
is said about version-numbers of jar?

On the Internet I don't find something on this error (only really missing jar
on windows machines).

Apparently jar doesn't follow the usual Unix-tool standards, so you can't ask
it (apparently) about its version or for help. Since I don't use jar, I don't
know what to do here.

Thanks for your consideration!

Oliver