feature/native-comp b3ade4d 2/7: Revert "Use `advice-flet' in place of `cl-letf' to avoid primitive...

[Andrea Corallo]

branch: feature/native-comp
commit b3ade4de179d4c13cd09e2b8066e09c66355d322
Author: Andrea Corallo <akrl@sdf.org>
Commit: Andrea Corallo <akrl@sdf.org>

    Revert "Use `advice-flet' in place of `cl-letf' to avoid primitive...
    
    This reverts commit 825e85b393a3d78ba43176ecc5bc1a9595d0fbea.
---
 test/lisp/abbrev-tests.el          |  6 ++--
 test/lisp/bookmark-tests.el        |  6 ++--
 test/lisp/emacs-lisp/rmc-tests.el  | 10 +++----
 test/lisp/files-tests.el           | 37 ++++++++++++------------
 test/lisp/kmacro-tests.el          | 58 ++++++++++++++++++--------------------
 test/lisp/net/tramp-tests.el       | 20 ++++++-------
 test/lisp/play/dissociate-tests.el |  4 +--
 test/lisp/replace-tests.el         | 45 ++++++++++++++---------------
 test/lisp/shadowfile-tests.el      | 32 ++++++++++-----------
 test/lisp/subr-tests.el            |  4 +--
 test/lisp/tempo-tests.el           | 10 +++----
 test/lisp/time-stamp-tests.el      |  4 +--
 12 files changed, 116 insertions(+), 120 deletions(-)

diff --git a/test/lisp/abbrev-tests.el b/test/lisp/abbrev-tests.el
index 9b998ad..aaf1d4a 100644
--- a/test/lisp/abbrev-tests.el
+++ b/test/lisp/abbrev-tests.el
@@ -279,7 +279,7 @@
   (let ((table (make-abbrev-table)))
     (with-temp-buffer
       (insert "some text foo ")
-      (advice-flet ((read-string (lambda (&rest _) "bar")))
+      (cl-letf (((symbol-function 'read-string) (lambda (&rest _) "bar")))
         (inverse-add-abbrev table "Global" 1)))
     (should (string= (abbrev-expansion "foo" table) "bar"))))
 
@@ -288,7 +288,7 @@
   (let ((table (make-abbrev-table)))
     (with-temp-buffer
       (insert "some text foo ")
-      (advice-flet ((read-string (lambda (&rest _) "bar")))
+      (cl-letf (((symbol-function 'read-string) (lambda (&rest _) "bar")))
         (inverse-add-abbrev table "Global" 2)))
     (should (string= (abbrev-expansion "text" table) "bar"))))
 
@@ -298,7 +298,7 @@
     (with-temp-buffer
       (insert "some     text foo")
       (goto-char (point-min))
-      (advice-flet ((read-string (lambda (&rest _) "bar")))
+      (cl-letf (((symbol-function 'read-string) (lambda (&rest _) "bar")))
         (inverse-add-abbrev table "Global" -1)))
     (should (string= (abbrev-expansion "text" table) "bar"))))
 
diff --git a/test/lisp/bookmark-tests.el b/test/lisp/bookmark-tests.el
index 26d75ce..c5959e4 100644
--- a/test/lisp/bookmark-tests.el
+++ b/test/lisp/bookmark-tests.el
@@ -633,9 +633,9 @@ testing `bookmark-bmenu-list'."
 
 (ert-deftest bookmark-test-bmenu-locate ()
   (let (msg)
-    (advice-flet ((message
-                   (lambda (&rest args)
-                     (setq msg (apply #'format args)))))
+    (cl-letf (((symbol-function 'message)
+               (lambda (&rest args)
+                 (setq msg (apply #'format args)))))
       (with-bookmark-bmenu-test
        (bookmark-bmenu-locate)
        (should (equal msg "/some/file"))))))
diff --git a/test/lisp/emacs-lisp/rmc-tests.el 
b/test/lisp/emacs-lisp/rmc-tests.el
index de6db13..5add24c 100644
--- a/test/lisp/emacs-lisp/rmc-tests.el
+++ b/test/lisp/emacs-lisp/rmc-tests.el
@@ -33,12 +33,10 @@
 
 (ert-deftest test-read-multiple-choice ()
   (dolist (char '(?y ?n))
-    (let ((str (if (eq char ?y) "yes" "no")))
-      (advice-flet ((read-event
-                     (lambda () char)))
-        (should (equal (list char str)
-                       (read-multiple-choice "Do it? "
-                                             '((?y "yes") (?n "no")))))))))
+    (cl-letf* (((symbol-function #'read-event) (lambda () char))
+               (str (if (eq char ?y) "yes" "no")))
+      (should (equal (list char str)
+                     (read-multiple-choice "Do it? " '((?y "yes") (?n 
"no"))))))))
 
 
 (provide 'rmc-tests)
diff --git a/test/lisp/files-tests.el b/test/lisp/files-tests.el
index 3829f50..1b964af 100644
--- a/test/lisp/files-tests.el
+++ b/test/lisp/files-tests.el
@@ -242,25 +242,24 @@ form.")
   "Test file prompting in directory named `~'.
 If we are in a directory named `~', the default value should not
 be $HOME."
-  (let* ((dir (make-temp-file "read-file-name-test" t))
-         (subdir (expand-file-name "./~/" dir)))
-    (advice-flet ((completing-read
-                   (lambda (_prompt _coll &optional _pred _req init _hist def 
_)
-                     (or def init))))
-      (unwind-protect
-          (progn
-            (make-directory subdir t)
-            (with-temp-buffer
-              (setq default-directory subdir)
-              (should-not (equal
-                           (expand-file-name (read-file-name "File: "))
-                           (expand-file-name "~/")))
-              ;; Don't overquote either!
-              (setq default-directory (concat "/:" subdir))
-              (should-not (equal
-                           (expand-file-name (read-file-name "File: "))
-                           (concat "/:/:" subdir)))))
-        (delete-directory dir 'recursive)))))
+  (cl-letf (((symbol-function 'completing-read)
+             (lambda (_prompt _coll &optional _pred _req init _hist def _)
+               (or def init)))
+            (dir (make-temp-file "read-file-name-test" t)))
+    (unwind-protect
+        (let ((subdir (expand-file-name "./~/" dir)))
+          (make-directory subdir t)
+          (with-temp-buffer
+            (setq default-directory subdir)
+            (should-not (equal
+                         (expand-file-name (read-file-name "File: "))
+                         (expand-file-name "~/")))
+            ;; Don't overquote either!
+            (setq default-directory (concat "/:" subdir))
+            (should-not (equal
+                         (expand-file-name (read-file-name "File: "))
+                         (concat "/:/:" subdir)))))
+      (delete-directory dir 'recursive))))
 
 (ert-deftest files-tests-file-name-non-special-quote-unquote ()
   (let (;; Just in case it is quoted, who knows.
diff --git a/test/lisp/kmacro-tests.el b/test/lisp/kmacro-tests.el
index cc0f48e..bb18c82 100644
--- a/test/lisp/kmacro-tests.el
+++ b/test/lisp/kmacro-tests.el
@@ -341,8 +341,8 @@ This is a regression test for: Bug#3412, Bug#11817."
     (message "")  ; Clear the echo area. (Bug#3412)
     (kmacro-tests-should-match-message "Type e to repeat macro"
       (kmacro-tests-should-insert "mmmmmm"
-        (advice-flet ((this-single-command-keys (lambda ()
-                                                  [?\C-x ?e])))
+        (cl-letf (((symbol-function #'this-single-command-keys) (lambda ()
+                                                                  [?\C-x ?e])))
           (kmacro-call-macro 3))
         ;; Check that it set up for repeat, and run the repeat.
         (funcall (lookup-key overriding-terminal-local-map "e"))))))
@@ -455,8 +455,8 @@ This is a regression test for: Bug#3412, Bug#11817."
       ;; commands so it should end the sequence.
       (let* ((end-key (kmacro-tests-get-kmacro-key 'kmacro-set-counter))
              (kmacro-tests-events (append events (list end-key))))
-        (advice-flet ((this-single-command-keys
-                       (lambda () first-event)))
+        (cl-letf (((symbol-function #'this-single-command-keys)
+                   (lambda () first-event)))
           (use-local-map kmacro-tests-keymap)
           (kmacro-tests-should-insert "ccbacb"
             ;; End #3 and launch loop to read events.
@@ -466,9 +466,9 @@ This is a regression test for: Bug#3412, Bug#11817."
       ;; so run it again with that at the end.
       (let* ((end-key (kmacro-tests-get-kmacro-key 'kmacro-edit-macro-repeat))
              (kmacro-tests-events (append events (list end-key))))
-        (advice-flet ((edit-kbd-macro #'ignore)
-                      (this-single-command-keys
-                       (lambda () first-event)))
+        (cl-letf (((symbol-function #'edit-kbd-macro) #'ignore)
+                  ((symbol-function #'this-single-command-keys)
+                   (lambda () first-event)))
           (use-local-map kmacro-tests-keymap)
           (kmacro-tests-should-insert "bbbbbaaba"
             (kmacro-end-or-call-macro-repeat 3)))))))
@@ -494,22 +494,20 @@ This is a regression test for: Bug#3412, Bug#11817."
                                        '("d" "c" "b" "a" "d" "c")))))
     (cl-letf ((kmacro-repeat-no-prefix t)
               (kmacro-call-repeat-key t)
-              (kmacro-call-repeat-with-arg nil))
-      (advice-flet ((this-single-command-keys (lambda ()
-                                                first-event)))
-        ;; "Record" some macros.
-        (dotimes (n 4)
-          (kmacro-tests-define-macro (make-vector 1 (+ ?a n))))
-
-        (use-local-map kmacro-tests-keymap)
-        ;; 6 views (the direct call plus the 5 in events) should
-        ;; cycle through the ring and get to the second-to-last
-        ;; macro defined.
-        (kmacro-tests-should-insert
-         "c"
-         (kmacro-tests-should-match-message
-          macros-regexp
-          (kmacro-tests-simulate-command '(kmacro-view-macro-repeat nil))))))))
+              (kmacro-call-repeat-with-arg nil)
+              ((symbol-function #'this-single-command-keys) (lambda ()
+                                                              first-event)))
+      ;; "Record" some macros.
+      (dotimes (n 4)
+        (kmacro-tests-define-macro (make-vector 1 (+ ?a n))))
+
+      (use-local-map kmacro-tests-keymap)
+      ;; 6 views (the direct call plus the 5 in events) should
+      ;; cycle through the ring and get to the second-to-last
+      ;; macro defined.
+      (kmacro-tests-should-insert "c"
+        (kmacro-tests-should-match-message macros-regexp
+          (kmacro-tests-simulate-command '(kmacro-view-macro-repeat nil)))))))
 
 (kmacro-tests-deftest kmacro-tests-bind-to-key-when-recording ()
   "Bind to key doesn't bind a key during macro recording."
@@ -544,18 +542,18 @@ This is a regression test for: Bug#3412, Bug#11817."
     (define-key map "\C-hi" 'info)
     (use-local-map map)
     ;; Try the command with yes-or-no-p set up to say no.
-    (advice-flet ((yes-or-no-p
-                   (lambda (prompt)
-                     (should (string-match-p "info" prompt))
-                     (should (string-match-p "C-h i" prompt))
-                     nil)))
+    (cl-letf (((symbol-function #'yes-or-no-p)
+               (lambda (prompt)
+                 (should (string-match-p "info" prompt))
+                 (should (string-match-p "C-h i" prompt))
+                 nil)))
       (kmacro-bind-to-key nil))
 
     (should (equal (where-is-internal 'info nil t)
                    (vconcat "\C-hi")))
     ;; Try it again with yes.
-    (advice-flet ((yes-or-no-p
-                   (lambda (_prompt) t)))
+    (cl-letf (((symbol-function #' yes-or-no-p)
+               (lambda (_prompt) t)))
       (kmacro-bind-to-key nil))
 
     (should-not (equal (where-is-internal 'info global-map t)
diff --git a/test/lisp/net/tramp-tests.el b/test/lisp/net/tramp-tests.el
index 0e4fcb5..3914f9a 100644
--- a/test/lisp/net/tramp-tests.el
+++ b/test/lisp/net/tramp-tests.el
@@ -2420,16 +2420,16 @@ This checks also `file-name-as-directory', 
`file-name-directory',
                        tramp--test-messages))))))))
 
            ;; Do not overwrite if excluded.
-           (advice-flet ((y-or-n-p (lambda (_prompt) t))
-                         ;; Ange-FTP.
-                         (yes-or-no-p (lambda (_prompt) t)))
+           (cl-letf (((symbol-function #'y-or-n-p) (lambda (_prompt) t))
+                     ;; Ange-FTP.
+                     ((symbol-function 'yes-or-no-p) (lambda (_prompt) t)))
              (write-region "foo" nil tmp-name nil nil nil 'mustbenew))
            ;; `mustbenew' is passed to Tramp since Emacs 26.1.
            (when (tramp--test-emacs26-p)
              (should-error
-              (advice-flet ((y-or-n-p #'ignore)
-                            ;; Ange-FTP.
-                            (yes-or-no-p 'ignore))
+              (cl-letf (((symbol-function #'y-or-n-p) #'ignore)
+                        ;; Ange-FTP.
+                        ((symbol-function 'yes-or-no-p) 'ignore))
                 (write-region "foo" nil tmp-name nil nil nil 'mustbenew))
                :type 'file-already-exists)
              (should-error
@@ -3522,11 +3522,11 @@ This tests also `make-symbolic-link', `file-truename' 
and `add-name-to-file'."
               :type 'file-already-exists))
            (when (tramp--test-expensive-test)
              ;; A number means interactive case.
-             (advice-flet ((yes-or-no-p #'ignore))
+             (cl-letf (((symbol-function #'yes-or-no-p) #'ignore))
                (should-error
                 (make-symbolic-link tmp-name1 tmp-name2 0)
                 :type 'file-already-exists)))
-           (advice-flet ((yes-or-no-p (lambda (_prompt) t)))
+           (cl-letf (((symbol-function #'yes-or-no-p) (lambda (_prompt) t)))
              (make-symbolic-link tmp-name1 tmp-name2 0)
              (should
               (string-equal
@@ -3598,11 +3598,11 @@ This tests also `make-symbolic-link', `file-truename' 
and `add-name-to-file'."
              (add-name-to-file tmp-name1 tmp-name2)
              :type 'file-already-exists)
             ;; A number means interactive case.
-            (advice-flet ((yes-or-no-p #'ignore))
+            (cl-letf (((symbol-function #'yes-or-no-p) #'ignore))
               (should-error
                (add-name-to-file tmp-name1 tmp-name2 0)
                :type 'file-already-exists))
-            (advice-flet ((yes-or-no-p (lambda (_prompt) t)))
+            (cl-letf (((symbol-function #'yes-or-no-p) (lambda (_prompt) t)))
               (add-name-to-file tmp-name1 tmp-name2 0)
               (should (file-regular-p tmp-name2)))
             (add-name-to-file tmp-name1 tmp-name2 'ok-if-already-exists)
diff --git a/test/lisp/play/dissociate-tests.el 
b/test/lisp/play/dissociate-tests.el
index 1583a51..e8d9031 100644
--- a/test/lisp/play/dissociate-tests.el
+++ b/test/lisp/play/dissociate-tests.el
@@ -25,8 +25,8 @@
 (require 'dissociate)
 
 (ert-deftest dissociate-tests-dissociated-press ()
-  (advice-flet ((y-or-n-p (lambda (_) nil))
-                (random  (lambda (_) 10)))
+  (cl-letf (((symbol-function 'y-or-n-p) (lambda (_) nil))
+            ((symbol-function 'random)  (lambda (_) 10)))
     (save-window-excursion
       (with-temp-buffer
         (insert "Lorem ipsum dolor sit amet")
diff --git a/test/lisp/replace-tests.el b/test/lisp/replace-tests.el
index 0f80847..aed14c3 100644
--- a/test/lisp/replace-tests.el
+++ b/test/lisp/replace-tests.el
@@ -443,28 +443,29 @@ Return the last evalled form in BODY."
          ;; Bind `read-event' to simulate user input.
          ;; If `replace-tests-bind-read-string' is non-nil, then
          ;; bind `read-string' as well.
-         (advice-flet ((read-event
-                        (lambda (&rest _args)
-                          (cl-incf ,count)
-                          (pcase ,count ; Build the clauses from CHAR-NUMS
-                            ,@(append
-                               (delq nil
-                                     (mapcar
-                                      (lambda (chr)
-                                        (when-let (it (alist-get chr 
char-nums))
-                                          (if (cdr it)
-                                              `(,(cons 'or it) ,chr)
-                                            `(,(car it) ,chr))))
-                                      '(?, ?\s ?u ?U ?E ?q)))
-                               `((_ ,def-chr))))))
-                       (read-string
-                        (if replace-tests-bind-read-string
-                            (lambda (&rest _args) 
replace-tests-bind-read-string)
-                          (lambda (&rest args)
-                            (apply #'read-string args))))
-                       (replace-highlight
-                        (lambda (&rest _args)
-                          (string-match "[A-Z ]" "ForestGreen"))))
+         (cl-letf (((symbol-function 'read-event)
+                    (lambda (&rest _args)
+                      (cl-incf ,count)
+                      (pcase ,count ; Build the clauses from CHAR-NUMS
+                        ,@(append
+                           (delq nil
+                                 (mapcar
+                                  (lambda (chr)
+                                    (when-let (it (alist-get chr char-nums))
+                                      (if (cdr it)
+                                          `(,(cons 'or it) ,chr)
+                                        `(,(car it) ,chr))))
+                                  '(?, ?\s ?u ?U ?E ?q)))
+                           `((_ ,def-chr))))))
+                   ((symbol-function 'read-string)
+                    (if replace-tests-bind-read-string
+                        (lambda (&rest _args) replace-tests-bind-read-string)
+                      (symbol-function 'read-string)))
+                   ;; Emulate replace-highlight clobbering match-data via
+                   ;; isearch-lazy-highlight-new-loop and sit-for (bug#36328)
+                   ((symbol-function 'replace-highlight)
+                    (lambda (&rest _args)
+                      (string-match "[A-Z ]" "ForestGreen"))))
            (perform-replace ,from ,to t 
replace-tests-perform-replace-regexp-flag nil))
          ,@body))))
 
diff --git a/test/lisp/shadowfile-tests.el b/test/lisp/shadowfile-tests.el
index 6a96646..f40f6a1 100644
--- a/test/lisp/shadowfile-tests.el
+++ b/test/lisp/shadowfile-tests.el
@@ -138,10 +138,10 @@ guaranteed by the originator of a cluster definition."
     (unwind-protect
        ;; We must mock `read-from-minibuffer' and `read-string', in
        ;; order to avoid interactive arguments.
-       (advice-flet ((read-from-minibuffer
-                      (lambda (&rest _args) (pop mocked-input)))
-                     (read-string
-                      (lambda (&rest _args) (pop mocked-input))))
+       (cl-letf* (((symbol-function #'read-from-minibuffer)
+                   (lambda (&rest _args) (pop mocked-input)))
+                  ((symbol-function #'read-string)
+                   (lambda (&rest _args) (pop mocked-input))))
 
           ;; Cleanup & initialize.
           (shadow--tests-cleanup)
@@ -255,10 +255,10 @@ guaranteed by the originator of a cluster definition."
     (unwind-protect
        ;; We must mock `read-from-minibuffer' and `read-string', in
        ;; order to avoid interactive arguments.
-       (advice-flet ((read-from-minibuffer
-                      (lambda (&rest _args) (pop mocked-input)))
-                     (read-string
-                      (lambda (&rest _args) (pop mocked-input))))
+       (cl-letf* (((symbol-function #'read-from-minibuffer)
+                   (lambda (&rest _args) (pop mocked-input)))
+                  ((symbol-function #'read-string)
+                   (lambda (&rest _args) (pop mocked-input))))
 
           ;; Cleanup & initialize.
           (shadow--tests-cleanup)
@@ -608,10 +608,10 @@ guaranteed by the originator of a cluster definition."
     (unwind-protect
        ;; We must mock `read-from-minibuffer' and `read-string', in
        ;; order to avoid interactive arguments.
-       (advice-flet ((read-from-minibuffer
-                      (lambda (&rest _args) (pop mocked-input)))
-                     (read-string
-                      (lambda (&rest _args) (pop mocked-input))))
+       (cl-letf* (((symbol-function #'read-from-minibuffer)
+                   (lambda (&rest _args) (pop mocked-input)))
+                  ((symbol-function #'read-string)
+                   (lambda (&rest _args) (pop mocked-input))))
 
           ;; Cleanup & initialize.
           (shadow--tests-cleanup)
@@ -669,10 +669,10 @@ guaranteed by the originator of a cluster definition."
     (unwind-protect
        ;; We must mock `read-from-minibuffer' and `read-string', in
        ;; order to avoid interactive arguments.
-       (advice-flet ((read-from-minibuffer
-                      (lambda (&rest _args) (pop mocked-input)))
-                     (read-string
-                      (lambda (&rest _args) (pop mocked-input))))
+       (cl-letf* (((symbol-function #'read-from-minibuffer)
+                   (lambda (&rest _args) (pop mocked-input)))
+                  ((symbol-function #'read-string)
+                   (lambda (&rest _args) (pop mocked-input))))
 
           ;; Cleanup & initialize.
           (shadow--tests-cleanup)
diff --git a/test/lisp/subr-tests.el b/test/lisp/subr-tests.el
index b131b50..035c064 100644
--- a/test/lisp/subr-tests.el
+++ b/test/lisp/subr-tests.el
@@ -337,8 +337,8 @@ cf. Bug#25477."
 (ert-deftest subr-tests-bug22027 ()
   "Test for https://debbugs.gnu.org/22027 ."
   (let ((default "foo") res)
-    (advice-flet ((read-string
-                   (lambda (_prompt _init _hist def) def)))
+    (cl-letf (((symbol-function 'read-string)
+               (lambda (_prompt _init _hist def) def)))
       (setq res (read-passwd "pass: " 'confirm (mapconcat #'string default 
"")))
       (should (string= default res)))))
 
diff --git a/test/lisp/tempo-tests.el b/test/lisp/tempo-tests.el
index 333abff..bfe4759 100644
--- a/test/lisp/tempo-tests.el
+++ b/test/lisp/tempo-tests.el
@@ -55,7 +55,7 @@
   (with-temp-buffer
     (tempo-define-template "test" '("hello " (p ">")))
     (let ((tempo-interactive t))
-      (advice-flet ((read-string (lambda (&rest _) "world")))
+      (cl-letf (((symbol-function 'read-string) (lambda (&rest _) "world")))
         (tempo-insert-template 'tempo-template-test nil))
       (should (equal (buffer-string) "hello world")))))
 
@@ -64,7 +64,7 @@
   (with-temp-buffer
     (tempo-define-template "test" '("hello " (P ">")))
     ;; By default, `tempo-interactive' is nil, `P' should ignore this.
-    (advice-flet ((read-string (lambda (&rest _) "world")))
+    (cl-letf (((symbol-function 'read-string) (lambda (&rest _) "world")))
       (tempo-insert-template 'tempo-template-test nil))
     (should (equal (buffer-string) "hello world"))))
 
@@ -73,7 +73,7 @@
   (with-temp-buffer
     (tempo-define-template "test" '("abcde" (r ">") "ghijk"))
     (let ((tempo-interactive t))
-      (advice-flet ((read-string (lambda (&rest _) "F")))
+      (cl-letf (((symbol-function 'read-string) (lambda (&rest _) "F")))
         (tempo-insert-template 'tempo-template-test nil))
       (should (equal (buffer-string) "abcdeFghijk")))))
 
@@ -82,7 +82,7 @@
   (with-temp-buffer
     (tempo-define-template "test" '("hello " (p ">" P1) " " (s P1)))
     (let ((tempo-interactive t))
-      (advice-flet ((read-string (lambda (&rest _) "world!")))
+      (cl-letf (((symbol-function 'read-string) (lambda (&rest _) "world!")))
         (tempo-insert-template 'tempo-template-test nil))
       (should (equal (buffer-string) "hello world! world!")))))
 
@@ -164,7 +164,7 @@
     ;; Test interactive use
     (emacs-lisp-mode)
     (let ((tempo-interactive t))
-      (advice-flet ((read-string (lambda (&rest _) "  (list 1 2 3)")))
+      (cl-letf (((symbol-function 'read-string) (lambda (&rest _) "  (list 1 2 
3)")))
         (tempo-insert-template 'tempo-template-test nil))
       (should (equal (buffer-string) "(progn\n  (list 1 2 3))")))))
 
diff --git a/test/lisp/time-stamp-tests.el b/test/lisp/time-stamp-tests.el
index ab662ff..e75e84b 100644
--- a/test/lisp/time-stamp-tests.el
+++ b/test/lisp/time-stamp-tests.el
@@ -57,8 +57,8 @@
 (defmacro with-time-stamp-system-name (name &rest body)
   "Force (system-name) to return NAME while evaluating BODY."
   (declare (indent defun))
-  `(advice-flet ((system-name
-                  (lambda () ,name)))
+  `(cl-letf (((symbol-function 'system-name)
+              (lambda () ,name)))
      ,@body))
 
 (defmacro time-stamp-should-warn (form)