grafts: Graft recursively.

Fixes <http://bugs.gnu.org/22139>.

* guix/grafts.scm (graft-derivation): Rename to...
(graft-derivation/shallow): ... this.
(graft-origin-file-name, item->deriver, non-self-references)
(cumulative-grafts, graft-derivation): New procedures
* tests/grafts.scm ("graft-derivation, grafted item is a direct
dependency"): Clarify title.  Use 'grafted' instead of 'graft' to refer
to the grafted derivation.
("graft-derivation, grafted item is an indirect dependency")
("graft-derivation, no dependencies on grafted output"): New tests.
* guix/packages.scm (input-graft): Change to take a package instead of
an input.
(input-cross-graft): Likewise.
(fold-bag-dependencies): New procedure.
(bag-grafts): Rewrite in terms of 'fold-bag-dependencies'.
* tests/packages.scm ("package-derivation, indirect grafts"): Comment out.
* doc/guix.texi (Security Updates): Mention run-time dependencies and
recursive grafting.

1 files changed, 6 insertions, 3 deletions

diff --git a/doc/guix.texi b/doc/guix.texi
index 4c9a91b399..5e62703380 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -10244,11 +10244,14 @@ Packages}).  Then, the original package definition is augmented with a
     (replacement bash-fixed)))
 @end example
 
-From there on, any package depending directly or indirectly on Bash that
-is installed will automatically be ``rewritten'' to refer to
+From there on, any package depending directly or indirectly on Bash---as
+reported by @command{guix gc --requisites} (@pxref{Invoking guix
+gc})---that is installed is automatically ``rewritten'' to refer to
 @var{bash-fixed} instead of @var{bash}.  This grafting process takes
 time proportional to the size of the package, but expect less than a
-minute for an ``average'' package on a recent machine.
+minute for an ``average'' package on a recent machine.  Grafting is
+recursive: when an indirect dependency requires grafting, then grafting
+``propagates'' up to the package that the user is installing.
 
 Currently, the graft and the package it replaces (@var{bash-fixed} and
 @var{bash} in the example above) must have the exact same @code{name}