Merge branch 'master' into core-updates

derivations: 'derivation' and related procedures return a single value.

* guix/derivations.scm (derivation->output-path,
  derivation->output-paths): New procedures.
  (derivation-path->output-path): Use 'derivation->output-path'.
  (derivation-path->output-paths): Use 'derivation->output-paths'.
  (derivation): Accept 'derivation?' objects as inputs.  Return a single
  value.
  (build-derivations): New procedure.
  (compiled-modules): Use 'derivation->output-paths'.
  (build-expression->derivation)[source-path]: Add case for when the
  input matches 'derivation?'.
  [prologue]: Accept 'derivation?' objects in INPUTS.
  [mod-dir, go-dir]: Use 'derivation->output-path'.
* guix/download.scm (url-fetch): Adjust to the single-value return.
* guix/packages.scm (package-output): Use 'derivation->output-path'.
* guix/scripts/build.scm (guix-build): When the argument is
  'derivation-path?', pass it through 'read-derivation'.
  Use 'derivation-file-name' to print out the .drv file names, and to
  register them.  Use 'derivation->output-path' instead of
  'derivation-path->output-path'.
* guix/scripts/package.scm (roll-back): Adjust to the single-value
  return.
  (guix-package): Use 'derivation->output-path'.
* guix/ui.scm (show-what-to-build): Adjust to deal with 'derivation?'
  objects instead of .drv file names.
* gnu/system/grub.scm (grub-configuration-file): Use
  'derivation->output-path' instead of 'derivation-path->output-path'.
* gnu/system/vm.scm (qemu-image, system-qemu-image): Likewise.
* tests/builders.scm, tests/derivations.scm, tests/packages.scm,
  tests/store.scm, tests/union.scm: Adjust to the new calling
  convention.
* doc/guix.texi (Defining Packages, The Store, Derivations): Adjust
  accordingly.

build, package: Add `--fallback' option.

* guix/scripts/build.scm (%options, show-help): Add `--fallback'.
  (guix-build): Call `set-build-options' with #:fallback?.
* guix/scripts/package.scm (%options, show-help): Add `--fallback'.
  (guix-package): Call `set-build-options' with #:fallback?.
* doc/guix.texi (Invoking guix package, Invoking guix build): Document
  `--fallback'.

build: Add `--target' option.

* guix/scripts/build.scm (derivations-from-package-expressions): Add
  `package-derivation' parameter.
  (show-help, %options): Add `--target'.
  (guix-build): Use `package-cross-derivation' when `--target' is
  passed.
* tests/guix-build.sh: Add dry-run test with `--target'.
* doc/guix.texi (Invoking guix build): Document `--target'.

Add `--max-silent-time' to `guix build' and `guix package'.

* guix/scripts/build.scm (%default-options): Add default
  `max-silent-time' value.
  (show-help, %options):  Add `--max-silent-time'.
  (guix-build): Pass `max-silent-time' to `set-build-options'.
* guix/scripts/package.scm (%default-options): Add default
  `max-silent-time' value.
  (show-help, %options):  Add `--max-silent-time'.
  (guix-package): Pass `max-silent-time' to `set-build-options'.
* guix/ui.scm (string->number*): New procedure.
* tests/derivations.scm ("build-expression->derivation and
  max-silent-time"): New test.
* doc/guix.texi (Invoking guix package, Invoking guix build): Document
  `--max-silent-time'.

ui: Add `args-fold*' and use it.

* guix/ui.scm (args-fold*): New procedure.
* guix/scripts/build.scm, guix/scripts/download.scm,
  guix/scripts/gc.scm, guix/scripts/hash.scm, guix/scripts/import.scm,
  guix/scripts/package.scm, guix/scripts/pull.scm,
  guix/scripts/refresh.scm: Use `args-fold*' instead of `args-fold'.

Merge branch 'master' into core-updates

Conflicts:
	Makefile.am
	gnu/packages/autotools.scm
	gnu/packages/guile.scm
	gnu/packages/python.scm
	gnu/packages/shishi.scm
	guix/gnu-maintenance.scm
	guix/scripts/build.scm
	guix/scripts/gc.scm
	guix/scripts/package.scm
	guix/scripts/substitute-binary.scm
	guix/ui.scm
	nix/nix-daemon/guix-daemon.cc
	test-env.in
	tests/nar.scm
	tests/store.scm

ui: Add a 'define-diagnostic' macro.

* guix/ui.scm (define-diagnostic): New macro, which is based on the
  previous version of 'warning'.
  (warning, leave): Redefine using 'define-diagnostic'.
  (report-error): New macro.
  (install-locale): Use 'warning' instead of 'format'.
  (call-with-error-handling): Adjust 'leave'.
* gnu/packages.scm (package-files): Use 'warning' instead of 'format'.
* guix/gnu-maintenance.scm (http-fetch): Use 'warning' and 'leave'.
* guix/scripts/build.scm (derivations-from-package-expressions, guix-build):
  Adjust 'leave'.
* guix/scripts/download.scm (guix-download): Adjust 'leave'.
* guix/scripts/gc.scm (size->number, %options): Adjust 'leave'.
* guix/scripts/package.scm (roll-back, guix-package): Adjust 'leave'.
* po/POTFILES.in: Add 'guix/gnu-maintenance.scm'.

scripts: Report what will be substituted.

* guix/derivations.scm (derivation-input-output-paths): New procedure.
  (derivation-prerequisites-to-build): New `use-substitutes?' keyword
  argument.  Change two return the list of substitutable paths as a
  second argument.
* guix/ui.scm (show-what-to-build): Turn `dry-run?' into a keyword
  argument.  New `use-substitutes?' keyword argument.  Use `fold2' and
  adjust to use both return values of
  `derivation-prerequisites-to-build'.  Display what will/would be
  downloaded.
* guix/scripts/build.scm (guix-build): Adjust accordingly.
* guix/scripts/package.scm (guix-package): Likewise.
* tests/derivations.scm ("derivation-prerequisites-to-build and
  substitutes"): New test.

ui: Add a `warning' macro.

* guix/ui.scm (program-name, guix-warning-port): New variables.
  (warning): New macro.
  (guix-main): Parametrize PROGRAM-NAME.
* guix/scripts/build.scm, guix/scripts/download.scm,
  guix/scripts/gc.scm, guix/scripts/package.scm: Adjust to use `leave'
  and `warning' consistently.

ui: Add a `warning' macro.

* guix/ui.scm (program-name, guix-warning-port): New variables.
  (warning): New macro.
  (guix-main): Parametrize PROGRAM-NAME.
* guix/scripts/build.scm, guix/scripts/download.scm,
  guix/scripts/gc.scm, guix/scripts/package.scm: Adjust to use `leave'
  and `warning' consistently.

Merge branch 'master' into core-updates

Conflicts:
	Makefile.am
	guix/scripts/gc.scm
	guix/scripts/package.scm
	guix/ui.scm
	tests/guix-package.sh

ui: Factorize `read/eval-package-expression'.

* guix/scripts/package.scm (read/eval-package-expression): Move to...
* guix/ui.scm (read/eval-package-expression): ... here.
* guix/scripts/build.scm (derivations-from-package-expressions): Use it.

ui: Factorize `show-what-to-build'.

* guix/scripts/package.scm (guix-package)[show-what-to-build]: Move to..
* guix/ui.scm (show-what-to-build): ... here.  Add a `store'
  parameter'.  Adjust callers.
* guix/scripts/build.scm (guix-build): Use it.  Remove `req' and `req*'
  variables.

scripts: Remove hyphen in the command name shown by `--version'.

* guix/scripts/build.scm (%options): Remove hyphen from the name passed
  to `show-version-and-exit'.
* guix/scripts/download.scm (%options): Likewise.
* guix/scripts/gc.scm (%options): Likewise.
* guix/scripts/import.scm (%options): Likewise.
* guix/scripts/package.scm (%options): Likewise.

scripts: Remove initialization now redundant with `initialize-guix'.

* guix/scripts/build.scm (guix-build): Remove calls to `install-locale',
  `textdomain', etc., now redundant with `initialize-guix'.
* guix/scripts/download.scm (guix-download): Likewise.
* guix/scripts/import.scm (guix-import): Likewise.
* guix/scripts/package.scm (guix-package): Likewise.
* guix/ui.scm: Remove export of `install-locale' and `initialize-guix'.
  (initialize-guix): Add docstring.

Replace individual scripts with master 'guix' script.

* scripts/guix.in: New script.

* Makefile.am (bin_SCRIPTS): Add 'scripts/guix'.  Remove 'guix-build',
  'guix-download', 'guix-import', 'guix-package', and 'guix-gc'.

  (MODULES): Add 'guix/scripts/build.scm', 'guix/scripts/download.scm',
  'guix/scripts/import.scm', 'guix/scripts/package.scm', and
  'guix/scripts/gc.scm'.

* configure.ac (AC_CONFIG_FILES): Add 'scripts/guix'.  Remove 'guix-build',
  'guix-download', 'guix-import', 'guix-package', and 'guix-gc'.

* guix-build.in, guix-download.in, guix-gc.in, guix-import.in,
  guix-package.in: Remove shell script boilerplate.  Move to guix-COMMAND.in
  to guix/scripts/COMMAND.scm.  Rename module from (guix-COMMAND) to
  (guix scripts COMMAND).  Change "guix-COMMAND" to "guix COMMAND" in
  usage help string.

* pre-inst-env.in: Add "@abs_top_builddir@/scripts" to the front of $PATH.
  Export $GUIX_UNINSTALLED.

* tests/guix-build.sh, tests/guix-daemon.sh, tests/guix-download.sh,
  tests/guix-gc.sh, tests/guix-package.sh: Use "guix COMMAND" instead of
  "guix-COMMAND".

* doc/guix.texi: Replace all occurrences of "guix-COMMAND" with
  "guix COMMAND".

* po/POTFILES.in: Update.

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.

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.

Augment `.dir-locals.el'.

* .dir-locals.el: Add more Scheme settings.
* guix-build.in, tests/base32.scm, tests/build-utils.scm,
  tests/builders.scm, tests/derivations.scm, tests/packages.scm,
  tests/snix.scm, tests/store.scm, tests/union.scm, tests/utils.scm:
  Remove redundant Emacs local variable settings.