[nongnu] elpa/logview d64abdd8a9 1/4: Fix refreshing log buffer contents often resulting in an error on Emacs 30.

[ELPA Syncer]

branch: elpa/logview
commit d64abdd8a95c2b7b6051852628bdbfc4b5b4d4ef
Author: Paul Pogonyshev <pogonyshev@gmail.com>
Commit: Paul Pogonyshev <pogonyshev@gmail.com>

    Fix refreshing log buffer contents often resulting in an error on Emacs 30.
---
 logview.el      |  5 ++++-
 test/logview.el | 24 ++++++++++++++++++++++--
 2 files changed, 26 insertions(+), 3 deletions(-)

diff --git a/logview.el b/logview.el
index 7cb8c14e4e..fb32cd3882 100644
--- a/logview.el
+++ b/logview.el
@@ -2985,7 +2985,10 @@ returns non-nil."
          ;; zero-based offset.
          (compare-from-bytes (1- (position-bytes compare-from))))
     (with-temp-buffer
-      (insert-file-contents file nil compare-from-bytes nil)
+      ;; As of Emacs 30 this fails when trying to read past the end of the 
file (in earlier Emacs versions it
+      ;; works, but doesn't insert anything).  Don't care to report anything 
to Emacs-devel (maybe it's even
+      ;; intentional in this case, don't know), just work with either behavior 
by suppressing all errors.
+      (ignore-errors (insert-file-contents file nil compare-from-bytes nil))
       (let ((temporary      (current-buffer))
             (temporary-size (buffer-size)))
         (if (and (>= temporary-size reassurance-chars)
diff --git a/test/logview.el b/test/logview.el
index 1a0f62e02f..f258e7362e 100644
--- a/test/logview.el
+++ b/test/logview.el
@@ -127,12 +127,14 @@ buffer if the test needs that."
   ;; results.  Of course, this has no visible effect when running
   ;; tests from command line, as customization never takes place in
   ;; this case to begin with.
-  (let (erase-customizations
+  (let (visit-it
+        erase-customizations
         extra-customizations
         warning-handling
         buffer-mode)
     (while (keywordp (car body))
       (pcase-exhaustive (pop body)
+        (:visit-it             (setf visit-it             (pop body)))
         (:extra-customizations (setf extra-customizations (eval (pop body) t)))
         (:warning-handling     (setf warning-handling     (pop body)))
         (:buffer-mode          (setf buffer-mode          (pop body)))))
@@ -150,7 +152,7 @@ buffer if the test needs that."
                                                        (`standard (apply 
original arguments))
                                                        (_         (error 
"Warning elevated to an error: %S" arguments)))))
          (with-temp-buffer
-           (insert-file-contents (expand-file-name ,filename 
logview--test-directory))
+           (insert-file-contents (expand-file-name ,filename 
logview--test-directory) ,visit-it)
            (,(or buffer-mode 'logview-mode))
            (should (eq major-mode ',(or buffer-mode 'logview-mode)))
            ,@body)))))
@@ -385,6 +387,24 @@ buffer if the test needs that."
     (should-error (logview-next-entry) :type 'user-error)))
 
 
+(ert-deftest logview-refresh-shrunk-log-file ()
+  (let ((file (make-temp-file "log")))
+    ;; Insert the contents of `log4j/en-1.log' over and over again, so that 
the `file' is long enough.
+    (with-temp-file file
+      (insert-file-contents (expand-file-name "log4j/en-1.log" 
logview--test-directory))
+      (let ((contents (buffer-string)))
+        (dotimes (_ 1000)
+          (insert contents)))
+      (should (> (buffer-size) logview-reassurance-chars)))
+    (logview--test-with-file file
+      :visit-it t
+      (should (equal logview--submode-name "SLF4J"))
+      ;; This essentially erases file contents.
+      (with-temp-file file)
+      (logview-refresh-buffer-as-needed)
+      (should (equal (buffer-size) 0)))))
+
+
 ;; RFC 5424 levels.
 ;;
 ;; The mock log file should have a list of log messages in the default