Fix misuses of NULL when talking about the NUL character

* lisp/subr.el (inhibit-null-byte-detection): Make it an obsolete alias.

* src/coding.c (setup_coding_system): Use new name.
(detect_coding): Rename null_byte_found => nul_byte_found.
(detect_coding_system): Use new name.
Rename null_byte_found => nul_byte_found.
(Fdefine_coding_system_internal): Use new name.
(syms_of_coding): Rename inhibit-null-byte-detection to
inhibit-nul-byte-detection.
* src/w16select.c (get_clipboard_data): null_char => nul_char.
* src/json.c (check_string_without_embedded_nuls): Rename from
check_string_without_embedded_nulls.
(Fjson_parse_string): Adjust accordingly.
* src/coding.h (enum define_coding_undecided_arg_index)
(enum coding_attr_index): ...null_byte... => ...nul_byte....
* lisp/info.el (info-insert-file-contents, Info-insert-dir):
* lisp/international/mule.el (define-coding-system):
* lisp/vc/vc-git.el (vc-git--call):
* doc/lispref/nonascii.texi (Lisp and Coding Systems): Use the new name.

4 files changed, 12 insertions, 10 deletions

diff --git a/lisp/info.el b/lisp/info.el
index c650d882572..f2a064abb67 100644
--- a/lisp/info.el
+++ b/lisp/info.el
@@ -642,14 +642,14 @@ Do the right thing if the file has been compressed or zipped."
           (insert-file-contents-literally fullname visit)
           (let ((inhibit-read-only t)
                 (coding-system-for-write 'no-conversion)
-                (inhibit-null-byte-detection t) ; Index nodes include null bytes
+                (inhibit-nul-byte-detection t) ; Index nodes include null bytes
                 (default-directory (or (file-name-directory fullname)
                                        default-directory)))
             (or (consp decoder)
                 (setq decoder (list decoder)))
             (apply #'call-process-region (point-min) (point-max)
                    (car decoder) t t nil (cdr decoder))))
-      (let ((inhibit-null-byte-detection t)) ; Index nodes include null bytes
+      (let ((inhibit-nul-byte-detection t)) ; Index nodes include null bytes
         (insert-file-contents fullname visit)))
 
     ;; Clear the caches of modified Info files.
@@ -1377,7 +1377,7 @@ is non-nil)."
                           ;; Index nodes include null bytes.  DIR
                           ;; files should not have indices, but who
                           ;; knows...
-                          (let ((inhibit-null-byte-detection t))
+                          (let ((inhibit-nul-byte-detection t))
                             (insert-file-contents file)
                             (setq Info-dir-file-name file)
                             (push (current-buffer) buffers)
diff --git a/lisp/international/mule.el b/lisp/international/mule.el
index 281e5297d63..ba30fee4961 100644
--- a/lisp/international/mule.el
+++ b/lisp/international/mule.el
@@ -819,10 +819,10 @@ VALUE is a CCL program name defined by `define-ccl-program'.  The
 CCL program reads a character sequence and writes a byte sequence
 as an encoding result.
 
-`:inhibit-null-byte-detection'
+`:inhibit-nul-byte-detection'
 
 VALUE non-nil means Emacs ignore null bytes on code detection.
-See the variable `inhibit-null-byte-detection'.  This attribute
+See the variable `inhibit-nul-byte-detection'.  This attribute
 is meaningful only when `:coding-type' is `undecided'.
 
 `:inhibit-iso-escape-detection'
@@ -867,7 +867,7 @@ non-ASCII files.  This attribute is meaningful only when
                                       :ccl-encoder
                                       :valids))
                                    ((eq coding-type 'undecided)
-                                    '(:inhibit-null-byte-detection
+                                    '(:inhibit-nul-byte-detection
                                       :inhibit-iso-escape-detection
                                       :prefer-utf-8))))))
 
@@ -920,8 +920,8 @@ non-ASCII files.  This attribute is meaningful only when
           (cons :name (cons name (cons :docstring (cons (purecopy docstring)
                                                         props)))))
     (setcdr (assq :plist common-attrs) props)
-    (apply 'define-coding-system-internal
-           name (mapcar 'cdr (append common-attrs spec-attrs)))))
+    (apply #'define-coding-system-internal
+           name (mapcar #'cdr (append common-attrs spec-attrs)))))
 
 (defun coding-system-doc-string (coding-system)
   "Return the documentation string for CODING-SYSTEM."
diff --git a/lisp/subr.el b/lisp/subr.el
index 6c0ad00afa5..f48ca545c9d 100644
--- a/lisp/subr.el
+++ b/lisp/subr.el
@@ -1511,6 +1511,8 @@ be a list of the form returned by `event-start' and `event-end'."
 (make-obsolete-variable 'x-gtk-use-window-move nil "26.1")
 
 (defvaralias 'messages-buffer-max-lines 'message-log-max)
+(define-obsolete-variable-alias 'inhibit-null-byte-detection
+  'inhibit-nul-byte-detection "27.1")
 
 ;;;; Alternate names for functions - these are not being phased out.
 
diff --git a/lisp/vc/vc-git.el b/lisp/vc/vc-git.el
index 6b8ed7e2c12..0f8c9c836ce 100644
--- a/lisp/vc/vc-git.el
+++ b/lisp/vc/vc-git.el
@@ -1629,9 +1629,9 @@ The difference to vc-do-command is that this function always invokes
 (defun vc-git--call (buffer command &rest args)
   ;; We don't need to care the arguments.  If there is a file name, it
   ;; is always a relative one.  This works also for remote
-  ;; directories.  We enable `inhibit-null-byte-detection', otherwise
+  ;; directories.  We enable `inhibit-nul-byte-detection', otherwise
   ;; Tramp's eol conversion might be confused.
-  (let ((inhibit-null-byte-detection t)
+  (let ((inhibit-nul-byte-detection t)
         (coding-system-for-read
          (or coding-system-for-read vc-git-log-output-coding-system))
         (coding-system-for-write