guix build: Add '--check'.

* guix/derivations.scm (build-derivations): Add optional 'mode'
parameter.
* guix/scripts/build.scm (%default-options): Add 'build-mode'.
(show-help, %options): Add '--check'.
(guix-build): Honor 'build-mode' key of OPTS.  Pass it to
'show-what-to-build' and 'build-derivations'.
* doc/guix.texi (Invoking guix build): Document it.
(Substitutes): Mention it.

guix build: Add '--rounds'.

* guix/scripts/build.scm (show-build-options-help)
(%standard-build-options): Add --rounds.
(set-build-options-from-command-line): Honor it.
* doc/guix.texi (Invoking guix build): Document it.
* doc/contributing.texi (Submitting Patches): Mention it.

gnu-maintenance: Add GNOME updater.

* guix/gnu-maintenance.scm (ftp-server/directory)[quirks]: Remove glib.
(false-if-ftp-error): New macro.
(latest-release*): Use it.
(non-emacs-gnu-package?): Rename to...
(pure-gnu-package?): ... this.  Add call to 'gnome-package?'.
(%gnu-updater): Adjust accordingly.
(gnome-package?, latest-gnome-release): New procedures.
(%gnome-updater): New variable.
* guix/scripts/refresh.scm (%updaters): Add %GNOME-UPDATER.
* doc/guix.texi (Invoking guix refresh): Mention it.

refresh: Bail out when asked for a nonexistent updater.

* guix/scripts/refresh.scm (lookup-updater): Call 'leave' when 'find'
returns #f.

edit: Don't assume that an emacs daemon is running.

* guix/scripts/edit.scm (%editor): Use Emacs as a default value.

edit: Allow command line arguments in $VISUAL and $EDITOR.

* guix/scripts/edit.scm (guix-edit): Fix the assumption that %editor is
a one word command.

guix build: Modularize transformation handling.

* guix/scripts/build.scm (options/resolve-packages): Remove.
(options->things-to-build, transform-package-source): New procedure.
(%transformations): New variable.
(options->transformation): New procedure.
(options->derivations): Rewrite to use 'options->things-to-build' and
'options->transformation'.

guix package: Refactor 'options->installable'.

* guix/scripts/package.scm (options->upgrade-predicate)
(store-item->manifest-entry): New procedures.
* guix/scripts/package.scm (options->installable): Use them.  Remove the
'packages-to-upgrade' and 'packages-to-install' variables by getting rid
of a level of indirection.

guix package: Move 'process-actions' out of sight.

* guix/scripts/package.scm (process-actions): New procedure, moved
from...
(guix-package): ... here.  Adjust accordingly.

guix package: Formalize the list of actions.

* guix/scripts/package.scm (roll-back-action, switch-generation-action)
(delete-generations-action, manifest-action): New procedures.
(%actions): New variable.
* guix/scripts/package.scm (guix-package)[process-action]: Rewrite to
traverse %ACTIONS.

guix package: Move 'build-and-use-profile' out of sight.

* guix/scripts/package.scm (build-and-use-profile): New procedure.
Adapted and moved from...
(guix-package)[process-actions]: ... here.  Adjust call sites.

guix package: Move a couple of procedures out of sight.

* guix/scripts/package.scm (ensure-default-profile, process-query): New
procedures, moved from...
(guix-package): ... here.

guix package: Remove unnecessary use of (%store).

* guix/scripts/package.scm (delete-matching-generations): Use STORE
instead of (%store).

refresh: Check updater availability at run time.

This is a followup to b68d2db, which added a check for updaters at
macro-expansion time.  The problem is that, when running 'guix pull',
Guile-JSON is found, so the PyPi updater (say) is added to %UPDATERS,
but then at run time Guile-JSON might be missing.

Reported by orbea on #guix.

* guix/scripts/refresh.scm (maybe-updater): Rewrite as 'syntax-rules'.
Produce code that checks conditions at run time.
(list-updaters): Update docstring.

guix build: Factorize build log query.

* guix/scripts/build.scm (show-build-log): New procedure.
(guix-build): New variable 'items'.  Use it and 'show-build-log'.

environment: Set build options early on.

This fixes a bug whereby some options, such as #:substitute-urls, would
be passed to the daemon too late to have an effect.

* guix/scripts/environment.scm (build-inputs): Remove call to
'set-build-options-from-command-line*'.
(guix-environment): Add call to 'set-build-options-from-command-line' as
early as possible.

lint: Do not report already-patched vulnerabilities.

* guix/scripts/lint.scm (patch-file-name): New procedure.
(check-vulnerabilities): Use it to filter out patched vulnerabilities.
* tests/lint.scm ("cve: one patched vulnerability"): New test.

substitute: Warn upon store prefix mismatches.

Suggested by Hynek Urban <hynek.urban@gmail.com>.

* guix/scripts/substitute.scm (fetch-narinfos): Move body to...
[do-fetch]: ... here.  New procedure.
Emit a warning when CACHE-INFO's prefix does not match.

lint: Add "cve" checker.

Fixes <http://bugs.gnu.org/21289>.

* guix/scripts/lint.scm (package-name->cpe-name, package-vulnerabilities)
(check-vulnerabilities): New procedures.
* guix/scripts/lint.scm (%checkers): Add "cve" checker.
* tests/lint.scm ("cve", "cve: one vulnerability"): New tests.
* doc/guix.texi (Invoking guix lint): Mention it.

import: hackage: Assume current 'ghc' package version.

* guix/scripts/import/hackage.scm (%default-options): Do it.
  (ghc-default-version): New variable.