vim-patch:8.0.1072: :highlight command causes a redraw even when nothing changed

Problem:    The :highlight command causes a redraw even when nothing changed.
Solution:   Only set "need_highlight_changed" when an attribute changed.
https://github.com/vim/vim/commit/99433291b135094d9592c41f96d3ccd60073e2c1

1 files changed, 87 insertions, 71 deletions

diff --git a/src/nvim/syntax.c b/src/nvim/syntax.c
index 86ce259a29..dcac907c5a 100644
--- a/src/nvim/syntax.c
+++ b/src/nvim/syntax.c
@@ -53,7 +53,7 @@ static bool did_syntax_onoff = false;
 struct hl_group {
   char_u      *sg_name;         ///< highlight group name
   char_u      *sg_name_u;       ///< uppercase of sg_name
-  int sg_cleared;               ///< "hi clear" was used
+  bool sg_cleared;              ///< "hi clear" was used
   int sg_attr;                  ///< Screen attr @see ATTR_ENTRY
   int sg_link;                  ///< link to this highlight group ID
   int sg_set;                   ///< combination of flags in \ref SG_SET
@@ -6492,10 +6492,12 @@ void do_highlight(const char *line, const bool forceit, const bool init)
   int attr;
   int id;
   int idx;
-  int dodefault = FALSE;
-  int doclear = FALSE;
-  int dolink = FALSE;
-  int error = FALSE;
+  struct hl_group *item;
+  struct hl_group item_before;
+  bool dodefault = false;
+  bool doclear = false;
+  bool dolink = false;
+  bool error = false;
   int color;
   bool is_normal_group = false;   // "Normal" group
 
@@ -6565,6 +6567,7 @@ void do_highlight(const char *line, const bool forceit, const bool init)
 
     from_id = syn_check_group((const char_u *)from_start,
                               (int)(from_end - from_start));
+    item = &HL_TABLE()[from_id - 1];
     if (strncmp(to_start, "NONE", 4) == 0) {
       to_id = 0;
     } else {
@@ -6572,7 +6575,7 @@ void do_highlight(const char *line, const bool forceit, const bool init)
                               (int)(to_end - to_start));
     }
 
-    if (from_id > 0 && (!init || HL_TABLE()[from_id - 1].sg_set == 0)) {
+    if (from_id > 0 && (!init || item->sg_set == 0)) {
       // Don't allow a link when there already is some highlighting
       // for the group, unless '!' is used
       if (to_id > 0 && !forceit && !init
@@ -6580,19 +6583,22 @@ void do_highlight(const char *line, const bool forceit, const bool init)
         if (sourcing_name == NULL && !dodefault) {
           EMSG(_("E414: group has settings, highlight link ignored"));
         }
-      } else {
-        if (!init)
-          HL_TABLE()[from_id - 1].sg_set |= SG_LINK;
-        HL_TABLE()[from_id - 1].sg_link = to_id;
-        HL_TABLE()[from_id - 1].sg_scriptID = current_SID;
-        HL_TABLE()[from_id - 1].sg_cleared = false;
+      } else if (item->sg_link != to_id
+                 || item->sg_scriptID != current_SID
+                 || item->sg_cleared) {
+        if (!init) {
+          item->sg_set |= SG_LINK;
+        }
+        item->sg_link = to_id;
+        item->sg_scriptID = current_SID;
+        item->sg_cleared = false;
         redraw_all_later(SOME_VALID);
+
+        // Only call highlight changed() once after multiple changes
+        need_highlight_changed = true;
       }
     }
 
-    // Only call highlight_changed() once, after sourcing a syntax file.
-    need_highlight_changed = true;
-
     return;
   }
 
@@ -6622,19 +6628,23 @@ void do_highlight(const char *line, const bool forceit, const bool init)
     return;
   }
   idx = id - 1;  // Index is ID minus one.
+  item = &HL_TABLE()[idx];
 
   // Return if "default" was used and the group already has settings
   if (dodefault && hl_has_settings(idx, true)) {
     return;
   }
 
-  is_normal_group = (STRCMP(HL_TABLE()[idx].sg_name_u, "NORMAL") == 0);
+  // Make a copy so we can check if any attribute actually changed
+  item_before = *item;
+  is_normal_group = (STRCMP(item->sg_name_u, "NORMAL") == 0);
 
   // Clear the highlighting for ":hi clear {group}" and ":hi clear".
   if (doclear || (forceit && init)) {
     highlight_clear(idx);
-    if (!doclear)
-      HL_TABLE()[idx].sg_set = 0;
+    if (!doclear) {
+      item->sg_set = 0;
+    }
   }
 
   char *key = NULL;
@@ -6659,9 +6669,9 @@ void do_highlight(const char *line, const bool forceit, const bool init)
       linep = (const char *)skipwhite((const char_u *)linep);
 
       if (strcmp(key, "NONE") == 0) {
-        if (!init || HL_TABLE()[idx].sg_set == 0) {
+        if (!init || item->sg_set == 0) {
           if (!init) {
-            HL_TABLE()[idx].sg_set |= SG_CTERM+SG_GUI;
+            item->sg_set |= SG_CTERM+SG_GUI;
           }
           highlight_clear(idx);
         }
@@ -6730,34 +6740,34 @@ void do_highlight(const char *line, const bool forceit, const bool init)
           break;
         }
         if (*key == 'C')   {
-          if (!init || !(HL_TABLE()[idx].sg_set & SG_CTERM)) {
+          if (!init || !(item->sg_set & SG_CTERM)) {
             if (!init) {
-              HL_TABLE()[idx].sg_set |= SG_CTERM;
+              item->sg_set |= SG_CTERM;
             }
-            HL_TABLE()[idx].sg_cterm = attr;
-            HL_TABLE()[idx].sg_cterm_bold = false;
+            item->sg_cterm = attr;
+            item->sg_cterm_bold = false;
           }
         } else if (*key == 'G') {
-          if (!init || !(HL_TABLE()[idx].sg_set & SG_GUI)) {
+          if (!init || !(item->sg_set & SG_GUI)) {
             if (!init) {
-              HL_TABLE()[idx].sg_set |= SG_GUI;
+              item->sg_set |= SG_GUI;
             }
-            HL_TABLE()[idx].sg_gui = attr;
+            item->sg_gui = attr;
           }
         }
       } else if (STRCMP(key, "FONT") == 0)   {
         // in non-GUI fonts are simply ignored
       } else if (STRCMP(key, "CTERMFG") == 0 || STRCMP(key, "CTERMBG") == 0) {
-        if (!init || !(HL_TABLE()[idx].sg_set & SG_CTERM)) {
+        if (!init || !(item->sg_set & SG_CTERM)) {
           if (!init) {
-            HL_TABLE()[idx].sg_set |= SG_CTERM;
+            item->sg_set |= SG_CTERM;
           }
 
           /* When setting the foreground color, and previously the "bold"
            * flag was set for a light color, reset it now */
-          if (key[5] == 'F' && HL_TABLE()[idx].sg_cterm_bold) {
-            HL_TABLE()[idx].sg_cterm &= ~HL_BOLD;
-            HL_TABLE()[idx].sg_cterm_bold = false;
+          if (key[5] == 'F' && item->sg_cterm_bold) {
+            item->sg_cterm &= ~HL_BOLD;
+            item->sg_cterm_bold = false;
           }
 
           if (ascii_isdigit(*arg)) {
@@ -6800,21 +6810,21 @@ void do_highlight(const char *line, const bool forceit, const bool init)
             // set/reset bold attribute to get light foreground
             // colors (on some terminals, e.g. "linux")
             if (bold == kTrue) {
-              HL_TABLE()[idx].sg_cterm |= HL_BOLD;
-              HL_TABLE()[idx].sg_cterm_bold = true;
+              item->sg_cterm |= HL_BOLD;
+              item->sg_cterm_bold = true;
             } else if (bold == kFalse) {
-              HL_TABLE()[idx].sg_cterm &= ~HL_BOLD;
+              item->sg_cterm &= ~HL_BOLD;
             }
           }
           // Add one to the argument, to avoid zero.  Zero is used for
           // "NONE", then "color" is -1.
           if (key[5] == 'F') {
-            HL_TABLE()[idx].sg_cterm_fg = color + 1;
+            item->sg_cterm_fg = color + 1;
             if (is_normal_group) {
               cterm_normal_fg_color = color + 1;
             }
           } else {
-            HL_TABLE()[idx].sg_cterm_bg = color + 1;
+            item->sg_cterm_bg = color + 1;
             if (is_normal_group) {
               cterm_normal_bg_color = color + 1;
               if (!ui_rgb_attached()) {
@@ -6841,58 +6851,61 @@ void do_highlight(const char *line, const bool forceit, const bool init)
           }
         }
       } else if (strcmp(key, "GUIFG") == 0)   {
-        if (!init || !(HL_TABLE()[idx].sg_set & SG_GUI)) {
-          if (!init)
-            HL_TABLE()[idx].sg_set |= SG_GUI;
+        if (!init || !(item->sg_set & SG_GUI)) {
+          if (!init) {
+            item->sg_set |= SG_GUI;
+          }
 
-          xfree(HL_TABLE()[idx].sg_rgb_fg_name);
+          xfree(item->sg_rgb_fg_name);
           if (strcmp(arg, "NONE")) {
-            HL_TABLE()[idx].sg_rgb_fg_name = (char_u *)xstrdup((char *)arg);
-            HL_TABLE()[idx].sg_rgb_fg = name_to_color((const char_u *)arg);
+            item->sg_rgb_fg_name = (char_u *)xstrdup((char *)arg);
+            item->sg_rgb_fg = name_to_color((const char_u *)arg);
           } else {
-            HL_TABLE()[idx].sg_rgb_fg_name = NULL;
-            HL_TABLE()[idx].sg_rgb_fg = -1;
+            item->sg_rgb_fg_name = NULL;
+            item->sg_rgb_fg = -1;
           }
         }
 
         if (is_normal_group) {
-          normal_fg = HL_TABLE()[idx].sg_rgb_fg;
+          normal_fg = item->sg_rgb_fg;
         }
       } else if (STRCMP(key, "GUIBG") == 0)   {
-        if (!init || !(HL_TABLE()[idx].sg_set & SG_GUI)) {
-          if (!init)
-            HL_TABLE()[idx].sg_set |= SG_GUI;
+        if (!init || !(item->sg_set & SG_GUI)) {
+          if (!init) {
+            item->sg_set |= SG_GUI;
+          }
 
-          xfree(HL_TABLE()[idx].sg_rgb_bg_name);
+          xfree(item->sg_rgb_bg_name);
           if (STRCMP(arg, "NONE") != 0) {
-            HL_TABLE()[idx].sg_rgb_bg_name = (char_u *)xstrdup((char *)arg);
-            HL_TABLE()[idx].sg_rgb_bg = name_to_color((const char_u *)arg);
+            item->sg_rgb_bg_name = (char_u *)xstrdup((char *)arg);
+            item->sg_rgb_bg = name_to_color((const char_u *)arg);
           } else {
-            HL_TABLE()[idx].sg_rgb_bg_name = NULL;
-            HL_TABLE()[idx].sg_rgb_bg = -1;
+            item->sg_rgb_bg_name = NULL;
+            item->sg_rgb_bg = -1;
           }
         }
 
         if (is_normal_group) {
-          normal_bg = HL_TABLE()[idx].sg_rgb_bg;
+          normal_bg = item->sg_rgb_bg;
         }
       } else if (strcmp(key, "GUISP") == 0)   {
-        if (!init || !(HL_TABLE()[idx].sg_set & SG_GUI)) {
-          if (!init)
-            HL_TABLE()[idx].sg_set |= SG_GUI;
+        if (!init || !(item->sg_set & SG_GUI)) {
+          if (!init) {
+            item->sg_set |= SG_GUI;
+          }
 
-          xfree(HL_TABLE()[idx].sg_rgb_sp_name);
+          xfree(item->sg_rgb_sp_name);
           if (strcmp(arg, "NONE") != 0) {
-            HL_TABLE()[idx].sg_rgb_sp_name = (char_u *)xstrdup((char *)arg);
-            HL_TABLE()[idx].sg_rgb_sp = name_to_color((const char_u *)arg);
+            item->sg_rgb_sp_name = (char_u *)xstrdup((char *)arg);
+            item->sg_rgb_sp = name_to_color((const char_u *)arg);
           } else {
-            HL_TABLE()[idx].sg_rgb_sp_name = NULL;
-            HL_TABLE()[idx].sg_rgb_sp = -1;
+            item->sg_rgb_sp_name = NULL;
+            item->sg_rgb_sp = -1;
           }
         }
 
         if (is_normal_group) {
-          normal_sp = HL_TABLE()[idx].sg_rgb_sp;
+          normal_sp = item->sg_rgb_sp;
         }
       } else if (strcmp(key, "START") == 0 || strcmp(key, "STOP") == 0)   {
         // Ignored for now
@@ -6901,11 +6914,11 @@ void do_highlight(const char *line, const bool forceit, const bool init)
         error = true;
         break;
       }
-      HL_TABLE()[idx].sg_cleared = false;
+      item->sg_cleared = false;
 
       // When highlighting has been given for a group, don't link it.
-      if (!init || !(HL_TABLE()[idx].sg_set & SG_LINK)) {
-        HL_TABLE()[idx].sg_link = 0;
+      if (!init || !(item->sg_set & SG_LINK)) {
+        item->sg_link = 0;
       }
 
       // Continue with next argument.
@@ -6934,14 +6947,17 @@ void do_highlight(const char *line, const bool forceit, const bool init)
     } else {
       set_hl_attr(idx);
     }
-    HL_TABLE()[idx].sg_scriptID = current_SID;
-    redraw_all_later(NOT_VALID);
+    item->sg_scriptID = current_SID;
   }
   xfree(key);
   xfree(arg);
 
-  // Only call highlight_changed() once, after sourcing a syntax file
-  need_highlight_changed = true;
+  // Only call highlight_changed() once, after a sequence of highlight
+  // commands, and only if an attribute actually changed
+  if (memcmp(item, &item_before, sizeof(item_before)) != 0) {
+    redraw_all_later(NOT_VALID);
+    need_highlight_changed = true;
+  }
 }
 
 #if defined(EXITFREE)