patch 9.0.0048: cursor in wrong column with mouse click after concealed text

Problem:    Cursor in wrong column with mouse click after concealed text.
Solution:   Store the text column when drawing text.

Author: brammool

src/drawline.c

@@ -779,7 +779,7 @@ win_line(
 	    trailcol = (colnr_T)STRLEN(ptr);
 	    while (trailcol > (colnr_T)0 && VIM_ISWHITE(ptr[trailcol - 1]))
 		--trailcol;
-	    trailcol += (colnr_T) (ptr - line);
+	    trailcol += (colnr_T)(ptr - line);
 	}
 	// find end of leading whitespace
 	if (wp->w_lcs_chars.lead || wp->w_lcs_chars.leadmultispace != NULL)
@@ -792,7 +792,7 @@ win_line(
 		leadcol = (colnr_T)0;
 	    else
 		// keep track of the first column not filled with spaces
-		leadcol += (colnr_T) (ptr - line) + 1;
+		leadcol += (colnr_T)(ptr - line) + 1;
 	}
     }
 
@@ -1027,12 +1027,14 @@ win_line(
     // Repeat for the whole displayed line.
     for (;;)
     {
+	char_u	*prev_ptr = ptr;
 #if defined(FEAT_CONCEAL) || defined(FEAT_SEARCH_EXTRA)
-	int has_match_conc = 0;	// match wants to conceal
+	int	has_match_conc = 0;	// match wants to conceal
 #endif
 #ifdef FEAT_CONCEAL
-	int did_decrement_ptr = FALSE;
+	int	did_decrement_ptr = FALSE;
 #endif
+
 	// Skip this quickly when working on the text.
 	if (draw_state != WL_LINE)
 	{
@@ -1392,6 +1394,7 @@ win_line(
 				      &match_conc, did_line_attr, lcs_eol_one,
 				      &on_last_col);
 		ptr = line + v;  // "line" may have been changed
+		prev_ptr = ptr;
 
 		// Do not allow a conceal over EOL otherwise EOL will be missed
 		// and bad things happen.
@@ -1553,6 +1556,7 @@ win_line(
 		    // have made it invalid.
 		    line = ml_get_buf(wp->w_buffer, lnum, FALSE);
 		    ptr = line + v;
+		    prev_ptr = ptr;
 # ifdef FEAT_CONCEAL
 		    // no concealing past the end of the line, it interferes
 		    // with line highlighting
@@ -1733,9 +1737,10 @@ win_line(
 	else
 	{
 #ifdef FEAT_LINEBREAK
-	    int c0;
+	    int		c0;
 #endif
 	    VIM_CLEAR(p_extra_free);
+	    prev_ptr = ptr;
 
 	    // Get a character from the line itself.
 	    c = *ptr;
@@ -1942,17 +1947,12 @@ win_line(
 # endif
 				can_spell))
 		    {
-			char_u	*prev_ptr, *p;
+			char_u	*p;
 			int	len;
 			hlf_T	spell_hlf = HLF_COUNT;
 
 			if (has_mbyte)
-			{
-			    prev_ptr = ptr - mb_l;
 			    v -= mb_l - 1;
-			}
-			else
-			    prev_ptr = ptr - 1;
 
 			// Use nextline[] if possible, it has the start of the
 			// next line concatenated.
@@ -2771,6 +2771,7 @@ win_line(
 		}
 #endif
 		ScreenAttrs[off] = char_attr;
+		ScreenCols[off] = MAXCOL;
 #ifdef FEAT_RIGHTLEFT
 		if (wp->w_p_rl)
 		{
@@ -2839,6 +2840,7 @@ win_line(
 		    ScreenLines[off] = ' ';
 		    if (enc_utf8)
 			ScreenLinesUC[off] = 0;
+		    ScreenCols[off] = MAXCOL;
 		    ++col;
 		    if (draw_color_col)
 			draw_color_col = advance_color_col(VCOL_HLC,
@@ -2992,6 +2994,8 @@ win_line(
 	    else
 		ScreenAttrs[off] = char_attr;
 
+	    ScreenCols[off] = (colnr_T)(prev_ptr - line);
+
 	    if (has_mbyte && (*mb_char2cells)(mb_c) > 1)
 	    {
 		// Need to fill two screen columns.
@@ -3013,6 +3017,9 @@ win_line(
 		// the character, otherwise highlighting won't stop.
 		if (tocol == vcol)
 		    ++tocol;
+
+		ScreenCols[off] = (colnr_T)(prev_ptr - line);
+
 #ifdef FEAT_RIGHTLEFT
 		if (wp->w_p_rl)
 		{

src/globals.h

@@ -32,15 +32,17 @@ EXTERN long	Columns INIT(= 80);	// nr of columns in the screen
  * The characters that are currently on the screen are kept in ScreenLines[].
  * It is a single block of characters, the size of the screen plus one line.
  * The attributes for those characters are kept in ScreenAttrs[].
+ * The byte offset in the line is kept in ScreenCols[].
  *
  * "LineOffset[n]" is the offset from ScreenLines[] for the start of line 'n'.
- * The same value is used for ScreenLinesUC[] and ScreenAttrs[].
+ * The same value is used for ScreenLinesUC[], ScreenAttrs[] and ScreenCols[].
  *
  * Note: before the screen is initialized and when out of memory these can be
  * NULL.
  */
 EXTERN schar_T	*ScreenLines INIT(= NULL);
 EXTERN sattr_T	*ScreenAttrs INIT(= NULL);
+EXTERN colnr_T  *ScreenCols INIT(= NULL);
 EXTERN unsigned	*LineOffset INIT(= NULL);
 EXTERN char_u	*LineWraps INIT(= NULL);	// line wraps to next line
 
@@ -62,7 +64,7 @@ EXTERN int	Screen_mco INIT(= 0);		// value of p_mco used when
 EXTERN schar_T	*ScreenLines2 INIT(= NULL);
 
 /*
- * Buffer for one screen line (characters and attributes).
+ * One screen line to be displayed.  Points into ScreenLines.
  */
 EXTERN schar_T	*current_ScreenLine INIT(= NULL);
 

src/mouse.c

@@ -1543,8 +1543,9 @@ jump_to_mouse(
     int		first;
     int		row = mouse_row;
     int		col = mouse_col;
+    colnr_T	col_from_screen = -1;
 #ifdef FEAT_FOLDING
-    int		mouse_char;
+    int		mouse_char = ' ';
 #endif
 
     mouse_past_bottom = FALSE;
@@ -1626,16 +1627,6 @@ jump_to_mouse(
     if (flags & MOUSE_SETPOS)
 	goto retnomove;				// ugly goto...
 
-#ifdef FEAT_FOLDING
-    // Remember the character under the mouse, it might be a '-' or '+' in the
-    // fold column.
-    if (row >= 0 && row < Rows && col >= 0 && col <= Columns
-						       && ScreenLines != NULL)
-	mouse_char = ScreenLines[LineOffset[row] + col];
-    else
-	mouse_char = ' ';
-#endif
-
     old_curwin = curwin;
     old_cursor = curwin->w_cursor;
 
@@ -1969,6 +1960,22 @@ jump_to_mouse(
 	}
     }
 
+    if (prev_row >= 0 && prev_row < Rows && prev_col >= 0 && prev_col <= Columns
+						       && ScreenLines != NULL)
+    {
+	int off = LineOffset[prev_row] + prev_col;
+
+	// Only use ScreenCols[] after the window was redrawn.  Mainly matters
+	// for tests, a user would not click before redrawing.
+	if (curwin->w_redr_type <= VALID_NO_UPDATE)
+	    col_from_screen = ScreenCols[off];
+#ifdef FEAT_FOLDING
+	// Remember the character under the mouse, it might be a '-' or '+' in
+	// the fold column.
+	mouse_char = ScreenLines[off];
+#endif
+    }
+
 #ifdef FEAT_FOLDING
     // Check for position outside of the fold column.
     if (
@@ -2001,16 +2008,40 @@ jump_to_mouse(
 	    redraw_cmdline = TRUE;	// show visual mode later
     }
 
-    curwin->w_curswant = col;
-    curwin->w_set_curswant = FALSE;	// May still have been TRUE
-    if (coladvance(col) == FAIL)	// Mouse click beyond end of line
+    if (col_from_screen >= 0)
+    {
+	// Use the column from ScreenCols[], it is accurate also after
+	// concealed characters.
+	curwin->w_cursor.col = col_from_screen;
+	if (col_from_screen == MAXCOL)
+	{
+	    curwin->w_curswant = col_from_screen;
+	    curwin->w_set_curswant = FALSE;	// May still have been TRUE
+	    mouse_past_eol = TRUE;
+	    if (inclusive != NULL)
+		*inclusive = TRUE;
+	}
+	else
+	{
+	    curwin->w_set_curswant = TRUE;
+	    if (inclusive != NULL)
+		*inclusive = FALSE;
+	}
+	check_cursor_col();
+    }
+    else
     {
-	if (inclusive != NULL)
-	    *inclusive = TRUE;
-	mouse_past_eol = TRUE;
+	curwin->w_curswant = col;
+	curwin->w_set_curswant = FALSE;	// May still have been TRUE
+	if (coladvance(col) == FAIL)	// Mouse click beyond end of line
+	{
+	    if (inclusive != NULL)
+		*inclusive = TRUE;
+	    mouse_past_eol = TRUE;
+	}
+	else if (inclusive != NULL)
+	    *inclusive = FALSE;
     }
-    else if (inclusive != NULL)
-	*inclusive = FALSE;
 
     count = IN_BUFFER;
     if (curwin != old_curwin || curwin->w_cursor.lnum != old_cursor.lnum