Build newest versions unless specified, and implement upgrades.

* gnu/packages.scm (find-newest-available-packages):
  New exported procedure.

* guix-build.in (newest-available-packages, find-best-packages-by-name):
  New procedures.
  (find-package): Use find-best-packages-by-name, to guarantee that
  if a version number is not specified, only the newest versions will
  be considered.

* guix-package.in (%options): Add --upgrade/-u option.
  (newest-available-packages, find-best-packages-by-name, upgradeable?):
  New procedures.
  (find-package): Use find-best-packages-by-name, to guarantee that
  if a version number is not specified, only the newest versions will
  be considered.
  (process-actions): Implement upgrade option.

* doc/guix.texi (Invoking guix-package): In the description of --install,
  mention that if no version number is specified, the newest available
  version will be selected.

1 files changed, 4 insertions, 3 deletions

diff --git a/doc/guix.texi b/doc/guix.texi
index 9cb1431bf1..80149326c1 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -491,9 +491,10 @@ Install @var{package}.
 
 @var{package} may specify either a simple package name, such as
 @code{guile}, or a package name followed by a hyphen and version number,
-such as @code{guile-1.8.8}.  In addition, @var{package} may contain a
-colon, followed by the name of one of the outputs of the package, as in
-@code{gcc:doc} or @code{binutils-2.22:lib}.
+such as @code{guile-1.8.8}.  If no version number is specified, the
+newest available version will be selected.  In addition, @var{package}
+may contain a colon, followed by the name of one of the outputs of the
+package, as in @code{gcc:doc} or @code{binutils-2.22:lib}.
 
 @cindex propagated inputs
 Sometimes packages have @dfn{propagated inputs}: these are dependencies