Use 'formatted-message' instead of '&message' where appropriate.

* gnu.scm (%try-use-modules): Use 'formatted-message' instead of
'&message'.
* gnu/machine/digital-ocean.scm (maybe-raise-unsupported-configuration-error):
Likewise.
* gnu/machine/ssh.scm (machine-check-file-system-availability): Likewise.
(machine-check-building-for-appropriate-system): Likewise.
(deploy-managed-host): Likewise.
(maybe-raise-unsupported-configuration-error): Likewise.
* gnu/packages.scm (search-patch): Likewise.
* gnu/services.scm (%service-with-default-value): Likewise.
(files->etc-directory): Likewise.
(fold-services): Likewise.
* gnu/system.scm (locale-name->definition*): Likewise.
* gnu/system/mapped-devices.scm (check-device-initrd-modules): Likewise.
(check-luks-device): Likewise.
* guix/channels.scm (latest-channel-instance): Likewise.
* guix/cve.scm (json->cve-items): Likewise.
* guix/git-authenticate.scm (commit-signing-key): Likewise.
(commit-authorized-keys): Likewise.
(authenticate-commit): Likewise.
(verify-introductory-commit): Likewise.
* guix/remote.scm (remote-pipe-for-gexp): Likewise.
* guix/scripts/graph.scm (assert-package): Likewise.
* guix/scripts/offload.scm (private-key-from-file*): Likewise.
* guix/ssh.scm (authenticate-server*): Likewise.
(open-ssh-session): Likewise.
(remote-inferior): Likewise.
* guix/ui.scm (matching-generations): Likewise.
* guix/upstream.scm (package-update): Likewise.
* tests/channels.scm ("latest-channel-instances, missing introduction for 'guix'"):
Catch 'formatted-message?'.
("authenticate-channel, wrong first commit signer"): Likewise.
* tests/lint.scm ("patches: not found"): Adjust message string.
* tests/packages.scm ("patch not found yields a run-time error"): Catch
'formatted-message?'.
* guix/lint.scm (check-patch-file-names): Handle 'formatted-message?'.
(check-derivation): Ditto.

gnu/system/mapped-devices.scm

@@ -25,6 +25,7 @@
   #:use-module (guix i18n)
   #:use-module ((guix diagnostics)
                 #:select (source-properties->location
+                          formatted-message
                           &fix-hint
                           &error-location))
   #:use-module (gnu services)
@@ -132,13 +133,13 @@ DEVICE must be a \"/dev\" file name."
     ;; "usb_storage"), not file names (e.g., "usb-storage.ko").  This is
     ;; OK because we have machinery that accepts both the hyphen and the
     ;; underscore version.
-    (raise (condition
-            (&message
-             (message (format #f (G_ "you may need these modules \
+    (raise (make-compound-condition
+            (formatted-message (G_ "you may need these modules \
 in the initrd for ~a:~{ ~a~}")
-                              device missing)))
-            (&fix-hint
-             (hint (format #f (G_ "Try adding them to the
+                               device missing)
+            (condition
+             (&fix-hint
+              (hint (format #f (G_ "Try adding them to the
 @code{initrd-modules} field of your @code{operating-system} declaration, along
 these lines:
 
@@ -151,9 +152,10 @@ these lines:
 
 If you think this diagnostic is inaccurate, use the @option{--skip-checks}
 option of @command{guix system}.\n")
-                           missing)))
-            (&error-location
-             (location (source-properties->location location)))))))
+                            missing))))
+            (condition
+             (&error-location
+              (location (source-properties->location location))))))))
 
 
 ;;;
@@ -215,13 +217,13 @@ option of @command{guix system}.\n")
         (if (uuid? source)
             (match (find-partition-by-luks-uuid (uuid-bytevector source))
               (#f
-               (raise (condition
-                       (&message
-                        (message (format #f (G_ "no LUKS partition with UUID '~a'")
-                                         (uuid->string source))))
-                       (&error-location
-                        (location (source-properties->location
-                                   (mapped-device-location md)))))))
+               (raise (make-compound-condition
+                       (formatted-message (G_ "no LUKS partition with UUID '~a'")
+                                          (uuid->string source))
+                       (condition
+                        (&error-location
+                         (location (source-properties->location
+                                    (mapped-device-location md))))))))
               ((? string? device)
                (check-device-initrd-modules device initrd-modules location)))
             (check-device-initrd-modules source initrd-modules location)))))