Introduce a LineNumberWrapped face

README.asciidoc

@@ -1032,6 +1032,8 @@ There are some builtins faces used by internal Kakoune functionalities:
  * `LineNumbers`: face used by the number_lines highlighter
  * `LineNumberCursor`: face used to highlight the line number of the main
      selection
+ * `LineNumberWrapped`: face used to highlight the line number of wrapped
+     lines
  * `MenuForeground`: face for the selected element in menus
  * `MenuBackground`: face for the not selected elements in menus
  * `Information`: face for the informations windows and information messages

doc/manpages/faces.asciidoc

@@ -68,6 +68,9 @@ areas of the user interface:
 *LineNumberCursor*::
 	face used to highlight the line number of the main selection
 
+*LineNumberWrapped*::
+	face used to highlight the line number of wrapped lines
+
 *MenuForeground*::
 	face for the selected element in menus
 

src/face_registry.cc

@@ -107,6 +107,7 @@ FaceRegistry::FaceRegistry()
         { "SecondaryCursor", Face{ Color::Black, Color::White } },
         { "LineNumbers", Face{ Color::Default, Color::Default } },
         { "LineNumberCursor", Face{ Color::Default, Color::Default, Attribute::Reverse } },
+        { "LineNumbersWrapped", Face{ Color::Default, Color::Default, Attribute::Italic } },
         { "MenuForeground", Face{ Color::White, Color::Blue } },
         { "MenuBackground", Face{ Color::Blue, Color::White } },
         { "MenuInfo", Face{ Color::Cyan, Color::Default } },

src/highlighters.cc

@@ -924,12 +924,14 @@ struct LineNumbersHighlighter : Highlighter
             return;
 
         const Face face = get_face("LineNumbers");
+        const Face face_wrapped = get_face("LineNumbersWrapped");
         const Face face_absolute = get_face("LineNumberCursor");
         int digit_count = compute_digit_count(context);
 
         char format[16];
         format_to(format, "%{}d{}", digit_count, m_separator);
         const int main_line = (int)context.selections().main().cursor().line + 1;
+        int last_line = -1;
         for (auto& line : display_buffer.lines())
         {
             const int current_line = (int)line.range().begin.line + 1;
@@ -939,8 +941,10 @@ struct LineNumbersHighlighter : Highlighter
             char buffer[16];
             snprintf(buffer, 16, format, std::abs(line_to_format));
             DisplayAtom atom{buffer};
-            atom.face = (m_hl_cursor_line and is_cursor_line) ? face_absolute : face;
+            atom.face = last_line == current_line ? face_wrapped :
+                ((m_hl_cursor_line and is_cursor_line) ? face_absolute : face);
             line.insert(line.begin(), std::move(atom));
+            last_line = current_line;
         }
     }