Merge branch 'core-updates'

lint: Add a 'derivation' checker.

* guix/scripts/lint.scm (check-derivation): New procedure.
  (%checkers): Add 'derivation' checker.
* tests/lint.scm ("derivation: invalid arguments"): New test.

lint: Report patches that cannot be found.

* guix/scripts/lint.scm (check-patch-file-names): Wrap body in 'guard'.
* tests/lint.scm ("patches: not found"): New test.

lint: Rename 'check-patches' to 'check-patch-file-names'.

* guix/scripts/lint.scm (check-patches): Rename to...
  (check-patch-file-names): ... this.  Rename 'filename' to 'file'.
  (%checkers): Adjust accordingly.
* tests/lint.scm ("patches: file names"): Likewise.

Merge branch 'master' into core-updates

lint: Report details about FTP errors.

* guix/scripts/lint.scm (probe-uri) <'ftp>: Pass more information about
  failures alongside 'ftp-response.
  (validate-uri) <ftp-response>: Handle it, and adjust "not reachable"
  message accordingly.

lint: Change misleading variable name.

* guix/scripts/lint.scm (probe-uri) <'ftp>: Rename 'port' to 'conn'.

Merge branch 'master' into core-updates

lint: Add tests for the 'source' checker.

* guix/scripts/lint.scm (check-source): Export.
* tests/lint.scm (%null-sha256): New procedure.
  ("source: 200", "source: 404"): New tests.

lint: handle FTP URIs.

* guix/scripts/lint.scm (probe-uri): handle FTP URIs.

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.

guix lint: Make the 'source' checker happy if at least one URI is valid.

Before that it would check all the URIs of each package.

* guix/scripts/lint.scm (validate-uri): Really return #f on failure and
  #t otherwise.
  (check-source): Replace 'for-each' with 'any'.

lint: add 'source' checker.

* guix/scripts/lint.scm (validate-uri?): New procedure.
  (%checkers): Add 'source' checker

Merge branch 'master' into core-updates

lint: Add tests for the 'home-page' checker.

Suggested by Cyril Roelandt <tipecaml@gmail.com>.

* tests/lint.scm (%http-server-port, %http-server-socket, %local-url,
  stub-http-server): New variables.
  (http-write, call-with-http-server): New procedures.
  (with-http-server): New macro.
  ("home-page: wrong home-page", "home-page: invalid URI", "home-page:
  host not found", "home-page: Connection refused", "home-page: 200",
  "home-page: 404"): New tests.
* guix/scripts/lint.scm (check-home-page): Export.

lint: Report on the package being checked.

* guix/scripts/lint.scm (run-checkers): Check
  whether (current-error-port) is a tty, and print the package being
  checked and the checker currently running when it is.

lint: Add 'home-page' checker.

* guix/build/download.scm (open-connection-for-uri): Export.
* guix/scripts/lint.scm (probe-uri, check-home-page): New procedures.
  (%checkers): Add 'home-page' checker.

lint: Fix typos in checker descriptions.

* guix/scripts/lint.scm (%checkers): "file names" (two words), and
  "synopses" (plural).

lint: Use localized checker descriptions.

* guix/scripts/lint.scm (list-checkers-and-exit): Wrap
  'lint-checker-description' call in (_ ...).

lint: Correctly internationalize warning messages.

* guix/scripts/lint.scm (emit-warning): Remove '_' call for format
  string.
  (check-description-style, check-inputs-should-be-native,
  check-synopsis-style, check-patches, check-gnu-synopsis+description):
  Wrap message in (_ ...).