Hi Guix,

I have a problem combining ".jar" sources with patches.

Here is my sources definition:

(define-public java-ecj
  (package (inherit java-ecj-3)
           (version "4.6.3")
           (source (origin
                     (method url-fetch)
                     (uri (string-append "http://archive.eclipse.org/eclipse/downloads/drops4/R-"
                                         version
                                         "-201703010400/ecjsrc-"
                                         version
                                         ".jar"))
                     (patches
                      (search-patches "java-ecj-buildxml-fix-manifest.patch"
                                      "java-ecj-include-props.patch"))
                     (sha256
                      (base32
                       "11cfgsdgznja1pvlxkjbqykxd7pcd5655vkm7s44xmahmap15gpl"))))
[...]

This worked pretty well until I added the patches:

./pre-inst-env  guix build java-ecj -K
;;; note: source file /home/bjoern/guix/wt/qt/gnu/packages/java.scm
;;;       newer than compiled /home/bjoern/guix/wt/qt/gnu/packages/java.go
building /gnu/store/wppz7bix1r4mhddjz6k4alfnxkm919gq-ecjsrc-4.6.3.tar.xz.drv...
/gnu/store/bl3pxxj6frg0dww8pj5dvh2d1akwvj47-tar-1.30/bin/tar: This does not look like a tar archive
/gnu/store/bl3pxxj6frg0dww8pj5dvh2d1akwvj47-tar-1.30/bin/tar: Skipping to next header
/gnu/store/bl3pxxj6frg0dww8pj5dvh2d1akwvj47-tar-1.30/bin/tar: Exiting with failure status due to previous errors
Backtrace:
           2 (primitive-load "/gnu/store/lg0dlhwf4mfz82697bvfdwi7d86?")
In ice-9/eval.scm:
    619:8  1 (_ #f)
In guix/build/utils.scm:
    616:6  0 (invoke _ . _)

guix/build/utils.scm:616:6: In procedure invoke:
Throw to key `srfi-34' with args `(#<condition &invoke-error [program: "/gnu/store/bl3pxxj6frg0dww8pj5dvh2d1akwvj47-tar-1.30/bin/tar" arguments: ("xvf" "/gnu/store/1vf8lxrnkgxw0zl8i2m8rf7jxcjg9f5b-ecjsrc-4.6.3.jar") exit-status: 2 term-signal: #f stop-signal: #f] 56dd40>)'.
note: keeping build directory `/tmp/guix-build-ecjsrc-4.6.3.tar.xz.drv-1'
builder for `/gnu/store/wppz7bix1r4mhddjz6k4alfnxkm919gq-ecjsrc-4.6.3.tar.xz.drv' failed with exit code 1
build of /gnu/store/wppz7bix1r4mhddjz6k4alfnxkm919gq-ecjsrc-4.6.3.tar.xz.drv failed


It looks like guix now wants to extract the jar-sources with "tar", no
longer with "jar". How can I tell Guix this is a jar-file to extract
from? Do I need to do that manually in a snippet? Any examples?

Thanks,

Björn