bug#22541: 25.0.50; highlight-regexp from isearch has is case-sensitive even if case-fold is active

[Tino Calancha <tino.calancha@gmail.com>]

Juri Linkov <juri@linkov.net> writes:

> The problem is that with introduction of char-folding, a hack responsible
> for case-folding in isearch-highlight-regexp that turns isearch-string
> into a case-insensitive regexp is not used anymore, i.e. it's overridden by
> isearch-regexp-function.  (Also note a FIXME comment in hi-lock-process-phrase)
>
> Since we can't change the value of font-lock-keywords-case-fold-search
> for font-lock based highlighting in hi-lock for individual regexps,
> the best solution is to rely on the feature allowing MATCHER in
> font-lock-keywords to be a function.  So we can let-bind case-fold-search
> in its lambda.
>
> Now the remaining problem is how to transfer case-fold from
> isearch-highlight-regexp down to hi-lock-set-pattern.
>
> Implementing pcre-style embedded modifiers is a good long-term goal,
> but we need to fix this for the next release.  What options do we have now?
> I see no other way than adding new argument to the chain of calls:

Hi Juri,

I think is a good moment to comeback to this issue once we have already
released Emacs 25.2.
I have updated your patch so that hi-lock-face-buffer checks search-upper-case
in interactive calls.  It works OK.
Since there isn't recent activity in the implementation of the pcre-style
embedded modifiers, we might use your patch in the meantime.

--8<-----------------------------cut here---------------start------------->8---
commit 7c3a515ec92f4bd9e82393dff1fcc4a3c2bb03b4
Author: Juri Linkov <juri@linkov.net>
Date:   Sat Apr 22 21:11:41 2017 +0900

    highlight-regexp: Honor case-fold-search
    
    Perform the matches of REGEXP as `isearch-forward' (Bug#22541).
    * lisp/hi-lock.el (hi-lock-face-buffer, hi-lock-set-pattern):
    Add optional arg CASE-FOLD.  All callers updated.
    * lisp/isearch.el (isearch-highlight-regexp): Call hi-lock-face-buffer
    with 3 arguments.

diff --git a/lisp/hi-lock.el b/lisp/hi-lock.el
index ebd18621ef..845b52c6b6 100644
--- a/lisp/hi-lock.el
+++ b/lisp/hi-lock.el
@@ -432,8 +432,9 @@ hi-lock-line-face-buffer
 ;;;###autoload
 (defalias 'highlight-regexp 'hi-lock-face-buffer)
 ;;;###autoload
-(defun hi-lock-face-buffer (regexp &optional face)
+(defun hi-lock-face-buffer (regexp &optional face case-fold)
   "Set face of each match of REGEXP to FACE.
+If optional arg CASE-FOLD is non-nil, then bind `case-fold-search' to it.
 Interactively, prompt for REGEXP using `read-regexp', then FACE.
 Use the global history list for FACE.
 
@@ -441,13 +442,18 @@ hi-lock-face-buffer
 use overlays for highlighting.  If overlays are used, the
 highlighting will not update as you type."
   (interactive
-   (list
-    (hi-lock-regexp-okay
-     (read-regexp "Regexp to highlight" 'regexp-history-last))
-    (hi-lock-read-face-name)))
+   (let* ((reg
+           (hi-lock-regexp-okay
+            (read-regexp "Regexp to highlight" 'regexp-history-last)))
+          (face (hi-lock-read-face-name))
+          (fold
+           (if search-upper-case
+               (isearch-no-upper-case-p reg t)
+             case-fold-search)))
+     (list reg face fold)))
   (or (facep face) (setq face 'hi-yellow))
   (unless hi-lock-mode (hi-lock-mode 1))
-  (hi-lock-set-pattern regexp face))
+  (hi-lock-set-pattern regexp face case-fold))
 
 ;;;###autoload
 (defalias 'highlight-phrase 'hi-lock-face-phrase-buffer)
@@ -689,11 +695,18 @@ hi-lock-read-face-name
       (add-to-list 'hi-lock-face-defaults face t))
     (intern face)))
 
-(defun hi-lock-set-pattern (regexp face)
-  "Highlight REGEXP with face FACE."
+(defun hi-lock-set-pattern (regexp face &optional case-fold)
+  "Highlight REGEXP with face FACE.
+If optional arg CASE-FOLD is non-nil, then bind `case-fold-search' to it."
   ;; Hashcons the regexp, so it can be passed to remove-overlays later.
   (setq regexp (hi-lock--hashcons regexp))
-  (let ((pattern (list regexp (list 0 (list 'quote face) 'prepend))))
+  (let ((pattern (list (if (eq case-fold 'undefined)
+                           regexp
+                         (byte-compile
+                          `(lambda (limit)
+                             (let ((case-fold-search ,case-fold))
+                               (re-search-forward ,regexp limit t)))))
+                       (list 0 (list 'quote face) 'prepend))))
     ;; Refuse to highlight a text that is already highlighted.
     (unless (assoc regexp hi-lock-interactive-patterns)
       (push pattern hi-lock-interactive-patterns)
@@ -711,12 +724,13 @@ hi-lock-set-pattern
                      (+ range-max (max 0 (- (point-min) range-min))))))
           (save-excursion
             (goto-char search-start)
-            (while (re-search-forward regexp search-end t)
-              (let ((overlay (make-overlay (match-beginning 0) (match-end 0))))
-                (overlay-put overlay 'hi-lock-overlay t)
-                (overlay-put overlay 'hi-lock-overlay-regexp regexp)
-                (overlay-put overlay 'face face))
-              (goto-char (match-end 0)))))))))
+            (let ((case-fold-search case-fold))
+              (while (re-search-forward regexp search-end t)
+                (let ((overlay (make-overlay (match-beginning 0) (match-end 0))))
+                  (overlay-put overlay 'hi-lock-overlay t)
+                  (overlay-put overlay 'hi-lock-overlay-regexp regexp)
+                  (overlay-put overlay 'face face))
+                (goto-char (match-end 0))))))))))
 
 (defun hi-lock-set-file-patterns (patterns)
   "Replace file patterns list with PATTERNS and refontify."
diff --git a/lisp/isearch.el b/lisp/isearch.el
index c34739d638..250d37b45e 100644
--- a/lisp/isearch.el
+++ b/lisp/isearch.el
@@ -1950,7 +1950,12 @@ isearch-highlight-regexp
 			      (regexp-quote s))))
 			isearch-string ""))
 		      (t (regexp-quote isearch-string)))))
-    (hi-lock-face-buffer regexp (hi-lock-read-face-name)))
+    (hi-lock-face-buffer regexp (hi-lock-read-face-name)
+                         (if (and (eq isearch-case-fold-search t)
+                                  search-upper-case)
+                             (isearch-no-upper-case-p
+                              isearch-string isearch-regexp)
+                           isearch-case-fold-search)))
   (and isearch-recursive-edit (exit-recursive-edit)))
 
 \f
--8<-----------------------------cut here---------------end--------------->8---
In GNU Emacs 26.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.22.11)
 of 2017-04-22
Repository revision: eb52828a439f674733ba70844b795c6673733572