Fix infloop in lsp-mode

* src/indent.c (line_number_display_width): Make sure the selected
window's buffer is current before using display code on it:
redisplay assumes that the window's buffer is current at all
times.  Reported by Evgeny Kurnevsky via lsp-mode's issue 1621,
https://github.com/emacs-lsp/lsp-mode/issues/1621.

diff --git a/src/indent.c b/src/indent.c
index 6246b544fbd21dac76d07e7671669015e2169521..de6b48956161a8ad390936ebbd3765a9e5f02961 100644 (file)
--- a/src/indent.c
+++ b/src/indent.c
@@ -1967,9 +1967,13 @@ line_number_display_width (struct window *w, int *width, int *pixel_width)
       struct it it;
       struct text_pos startpos;
       bool saved_restriction = false;
+      struct buffer *old_buf = current_buffer;
       ptrdiff_t count = SPECPDL_INDEX ();
       SET_TEXT_POS_FROM_MARKER (startpos, w->start);
       void *itdata = bidi_shelve_cache ();
+
+      /* Make sure W's buffer is the current one.  */
+      set_buffer_internal_1 (XBUFFER (w->contents));
       /* We want to start from window's start point, but it could be
         outside the accessible region, in which case we widen the
         buffer temporarily.  It could even be beyond the buffer's end
@@ -1998,6 +2002,7 @@ line_number_display_width (struct window *w, int *width, int *pixel_width)
       *pixel_width = it.lnum_pixel_width;
       if (saved_restriction)
        unbind_to (count, Qnil);
+      set_buffer_internal_1 (old_buf);
       bidi_unshelve_cache (itdata, 0);
     }
 }