feat(jumplist): allow opting out of removing unloaded buffers (#30419)

Problem:  Cannot opt out of removing unloaded buffers from the jumplist.
Solution: Only enable that with "clean" flag in 'jumpoptions'.

src/nvim/buffer.c

@@ -1395,8 +1395,10 @@ int do_buffer(int action, int start, int dir, int count, int forceit)
 
     // If the buffer to be deleted is not the current one, delete it here.
     if (buf != curbuf) {
-      // Remove the buffer to be deleted from the jump list.
-      buf_remove_from_jumplist(buf);
+      if (jop_flags & JOP_CLEAN) {
+        // Remove the buffer to be deleted from the jump list.
+        buf_remove_from_jumplist(buf);
+      }
 
       close_windows(buf, false);
 
@@ -1419,28 +1421,37 @@ int do_buffer(int action, int start, int dir, int count, int forceit)
     if (au_new_curbuf.br_buf != NULL && bufref_valid(&au_new_curbuf)) {
       buf = au_new_curbuf.br_buf;
     } else if (curwin->w_jumplistlen > 0) {
-      // Remove the current buffer from the jump list.
-      buf_remove_from_jumplist(curbuf);
+      if (jop_flags & JOP_CLEAN) {
+        // Remove the current buffer from the jump list.
+        buf_remove_from_jumplist(curbuf);
+      }
 
       // It's possible that we removed all jump list entries, in that case we need to try another
       // approach
       if (curwin->w_jumplistlen > 0) {
-        // If the index is the same as the length, the current position was not yet added to the jump
-        // list. So we can safely go back to the last entry and search from there.
-        if (curwin->w_jumplistidx == curwin->w_jumplistlen) {
-          curwin->w_jumplistidx = curwin->w_jumplistlen - 1;
-        }
-
         int jumpidx = curwin->w_jumplistidx;
 
+        if (jop_flags & JOP_CLEAN) {
+          // If the index is the same as the length, the current position was not yet added to the
+          // jump list. So we can safely go back to the last entry and search from there.
+          if (jumpidx == curwin->w_jumplistlen) {
+            jumpidx = curwin->w_jumplistidx = curwin->w_jumplistlen - 1;
+          }
+        } else {
+          jumpidx--;
+          if (jumpidx < 0) {
+            jumpidx = curwin->w_jumplistlen - 1;
+          }
+        }
+
         forward = jumpidx;
-        do {
+        while ((jop_flags & JOP_CLEAN) || jumpidx != curwin->w_jumplistidx) {
           buf = buflist_findnr(curwin->w_jumplist[jumpidx].fmark.fnum);
 
           if (buf != NULL) {
-            // Skip unlisted bufs.  Also skip a quickfix
+            // Skip current and unlisted bufs.  Also skip a quickfix
             // buffer, it might be deleted soon.
-            if (!buf->b_p_bl || bt_quickfix(buf)) {
+            if (buf == curbuf || !buf->b_p_bl || bt_quickfix(buf)) {
               buf = NULL;
             } else if (buf->b_ml.ml_mfp == NULL) {
               // skip unloaded buf, but may keep it for later
@@ -1451,8 +1462,10 @@ int do_buffer(int action, int start, int dir, int count, int forceit)
             }
           }
           if (buf != NULL) {         // found a valid buffer: stop searching
-            curwin->w_jumplistidx = jumpidx;
-            update_jumplist = false;
+            if (jop_flags & JOP_CLEAN) {
+              curwin->w_jumplistidx = jumpidx;
+              update_jumplist = false;
+            }
             break;
           }
           // advance to older entry in jump list
@@ -1465,7 +1478,7 @@ int do_buffer(int action, int start, int dir, int count, int forceit)
           if (jumpidx == forward) {               // List exhausted for sure
             break;
           }
-        } while (jumpidx != curwin->w_jumplistidx);
+        }
       }
     }
 
@@ -3726,7 +3739,7 @@ void ex_buffer_all(exarg_T *eap)
 
       // Open the buffer in this window.
       swap_exists_action = SEA_DIALOG;
-      set_curbuf(buf, DOBUF_GOTO, false);
+      set_curbuf(buf, DOBUF_GOTO, !(jop_flags & JOP_CLEAN));
       if (!bufref_valid(&bufref)) {
         // Autocommands deleted the buffer.
         swap_exists_action = SEA_NONE;

src/nvim/option_vars.h

@@ -527,6 +527,7 @@ EXTERN char *p_jop;             ///< 'jumpooptions'
 EXTERN unsigned jop_flags;
 #define JOP_STACK               0x01
 #define JOP_VIEW                0x02
+#define JOP_CLEAN               0x04
 EXTERN char *p_keymap;          ///< 'keymap'
 EXTERN char *p_kp;              ///< 'keywordprg'
 EXTERN char *p_km;              ///< 'keymodel'

src/nvim/options.lua

@@ -4484,7 +4484,7 @@ return {
     {
       abbreviation = 'jop',
       cb = 'did_set_jumpoptions',
-      defaults = { if_true = '' },
+      defaults = { if_true = 'clean' },
       deny_duplicates = true,
       desc = [=[
         List of words that change the behavior of the |jumplist|.
@@ -4497,6 +4497,9 @@ return {
           view          When moving through the jumplist, |changelist|,
         		|alternate-file| or using |mark-motions| try to
         		restore the |mark-view| in which the action occurred.
+
+          clean         Remove unloaded buffers from the jumplist.
+        		EXPERIMENTAL: this flag may change in the future.
       ]=],
       expand_cb = 'expand_set_jumpoptions',
       full_name = 'jumpoptions',

src/nvim/optionstr.c

@@ -136,7 +136,7 @@ static char *(p_fdc_values[]) = { "auto", "auto:1", "auto:2", "auto:3", "auto:4"
                                   "5", "6", "7", "8", "9", NULL };
 static char *(p_spo_values[]) = { "camel", "noplainbuffer", NULL };
 static char *(p_icm_values[]) = { "nosplit", "split", NULL };
-static char *(p_jop_values[]) = { "stack", "view", NULL };
+static char *(p_jop_values[]) = { "stack", "view", "clean", NULL };
 static char *(p_tpf_values[]) = { "BS", "HT", "FF", "ESC", "DEL", "C0", "C1", NULL };
 static char *(p_rdb_values[]) = { "compositor", "nothrottle", "invalid", "nodelta", "line",
                                   "flush", NULL };