profiles: Distinguish downgrades from upgrades.

Fixes <http://bugs.gnu.org/19764>.

* guix/profiles.scm (manifest-transaction-effects): Return downgraded
  packages as a fourth value.
* guix/ui.scm (show-manifest-transaction): Adjust accordingly.
* tests/profiles.scm ("manifest-transaction-effects and downgrades"):
  New test.

ui: Simplify 'show-manifest-transaction' test.

* tests/ui.scm ("show-manifest-transaction"): Remove useless call to
  'manifest-transaction-effects'.

serialization: Check for EOF and incomplete input conditions.

Fixes <http://bugs.gnu.org/19756>.
Reported by <sleep_walker@suse.cz>.

* guix/serialization.scm (currently-restored-file): New variable.
  (get-bytevector-n*): New procedure.
  (read-int, read-long-long, read-string, read-latin1-string,
  read-contents): Use it instead of 'get-bytevector-n'.
  (restore-file): Parameterize 'currently-restored-file' and set it.
* tests/nar.scm ("restore-file with incomplete input"): New test.

tests: Disable grafts when comparing derivations.

Fixes a regression introduced with the grafting of Patch in 3f11f01.

* tests/packages.scm ("reference to non-existent output"): Wrap in
  'parameterize'.

guix package: Make custom profiles actual indirect roots.

Before that, any profile generation built when '-p' is used would
effectively become a permanent GC root because the symlink in
/var/guix/gcroots/auto would point directly to /gnu/store/...-profile.

* guix/scripts/package.scm (maybe-register-gc-root): Rename to...
  (register-gc-root): ... this.  Remove conditional, and replace call to
  'canonicalize-path' with (string-append (getcwd) "/" ...).
  (guix-package): Call 'register-gc-root' only if PROFILE is different
  from %CURRENT-PROFILE.
* tests/guix-package.sh: Add test case.

tests: Skip 'guix-register' when the socket name length is exceeded.

* tests/guix-register.sh: Before running 'guix-daemon', check whether
  the socket name length exceeds the system limitation.

tests: Don't dump the list of dead items in the test log.

* tests/store.scm ("dead-paths"): Wrap result in '->bool'.

store: Add 'build-things'.

* guix/store.scm (operation-id): Rename 'build-derivations' to
  'build-things', as per Nix commit 1aba0bf0.
  (build-derivations): Rename to...
  (build-things): ... this.  Keep 'build-derivations' as an alias.
  (build): New procedure.
* tests/store.scm ("build-things with output path",
  "substitute + build-things with output path"): New tests.

tests: Add 'with-derivation-substitute' and use it.

* guix/tests.scm (%substitute-directory): New variable.
  (call-with-derivation-narinfo): Use it.
  (call-with-derivation-substitute): New procedure.
  (with-derivation-substitute): New macro.
* tests/store.scm ("substitute"): Use 'with-derivation-substitute'.
  ("substitute, corrupt output hash"): Likewise.

tests: Further factorize substitute mocks.

* guix/tests.scm (derivation-narinfo): Turn 'nar' into a keyword
  parameter.  Add #:sha256 parameter, and honor it.
  (call-with-derivation-narinfo): Add #:sha256 and pass it to
  'derivation-narinfo'.
  (with-derivation-narinfo): Extend with support for (sha256 => value).
* tests/store.scm ("substitute query"): Use 'with-derivation-narinfo'.
  ("substitute"): Likewise.
  ("substitute, corrupt output hash"): Likewise.
  ("substitute --fallback"): Likewise.
* tests/derivations.scm: Remove Emacs local variable.

tests: Use 'with-store' as appropriate.

* tests/store.scm ("no substitutes", "substitute query",
  "substitute", "substitute, corrupt output hash",
  "substitute --fallback"): Use 'with-store' instead of
  'open-connection'.

lint: Fix argument parsing when several packages are specified.

* guix/scripts/lint.scm (%options) <--checkers>: Remove 'arg-handler'
  parameter, and return a single value.
  (guix-lint)[parse-options]: Remove 'arg-handler' parameter from
  handlers.  Remove second seed to 'args-fold*'.
* tests/guix-lint.sh: Add test.

derivations: Raise an error for references to non-existent outputs.

Fixes <http://bugs.gnu.org/19630>.
Reported by Ricardo Wurmus <ricardo.wurmus@mdc-berlin.de>.

* guix/derivations.scm (&derivation-error,
  &derivation-missing-output-error): New error conditions.
  (derivation->output-path): Raise a '&derivation-missing-output-error'
  if OUTPUT is not an output of DRV.
* guix/ui.scm (call-with-error-handling): Add case for
  'derivation-missing-output-error?'.
  (show-what-to-build): Check whether (derivation-outputs drv) is
  empty.
* tests/packages.scm ("reference to non-existent output"): Add test.

gnu: 'search-patch' raises an error when a patch is not found.

* gnu/packages.scm (search-patch): Raise an error condition when
  'search-path' returns #f.
* tests/packages.scm ("patch not found yields a run-time error"): New
  test.

records: Add support for delayed fields.

* guix/records.scm (make-syntactic-constructor): Add #:delayed
  parameter.
  [delayed-field?]: New procedure.
  [wrap-field-value]: Use it.
  (define-record-type*)[delayed-field?, wrapped-field?]: New procedures.
  [thunked-field-accessor-name]: Rename to...
  [wrapped-field-accessor-name]: ... this.
  [field-spec->srfi-9]: Change 'thunked' to 'wrapped'.
  [delayed-field-accessor-definition]: New procedure.
  Compute delayed-field accessors and emit them.  Pass #:delayed to
  'make-syntactic-constructor'.
* tests/records.scm ("define-record-type* & delayed",
  "define-record-type* & delayed & default",
  "define-record-type* & delayed & inherited"): New tests.

tests: Adjust syscall tests for 2.6ish Linux.

* tests/syscalls.scm ("set-network-interface-flags",
  "set-network-interface-address"): Accept EACCES as a valid result.

monads: Add the state monad.

* guix/monads.scm (state-return, state-bind, run-with-state,
  current-state, set-current-state, state-push, state-pop): New
  procedures.
  (%state-monad): New variable.
* tests/monads.scm (%monads): Add %STATE-MONAD.
  (%monad-run): Add 'run-with-state'.
  (values->list): New macro.
  ("set-current-state", "state-push etc."): New tests.

store: Add #:recursive? parameter to 'export-paths'.

* guix/store.scm (export-paths): Add #:recursive? parameter and honor
  it.
* tests/store.scm ("export/import incomplete", "export/import
  recursive"): New tests.

Merge branch 'core-updates'

Conflicts:
	gnu/packages/bootstrap.scm

packages: Convert source derivations to monadic style.

* guix/packages.scm (origin->derivation): Take body from
  'package-source-derivation', and change it to monadic style.  Expect
  METHOD to a monadic procedure.
  (package-source-derivation): Define in terms of 'origin->derivation'.
* guix/download.scm (url-fetch): Remove 'store' argument.  Remove
  'guile-for-build' variable.  Turn into a monadic procedure.
* guix/git-download.scm (git-fetch): Likewise.
* guix/svn-download.scm (svn-fetch): Likewise.
* tests/builders.scm (url-fetch*): New procedure.
  Change tests to call 'url-fetch*' instead of 'url-fetch'.
* tests/packages.scm ("package-source-derivation, snippet"): Remove
  'store' parameter of 'fetch' and change it to use 'interned-file'
  instead of 'add-to-store'.
* gnu/packages/bootstrap.scm (bootstrap-origin)[boot]: Remove 'store'
  parameter.