vim-patch:8.0.0621: :stag does not respect 'switchbuf'

Problem:    The ":stag" command does not respect 'switchbuf'.
Solution:   Check 'switchbuf' for tag commands that may open a new window.
            (Ingo Karkat, closes vim/vim#1681)  Define macros for the return values
            of getfile().
https://github.com/vim/vim/commit/8ad80dea089ffeb1a845199c013e9bb4be1cd22e

7 files changed, 124 insertions, 37 deletions

diff --git a/src/nvim/buffer.c b/src/nvim/buffer.c
index eb781b1be0..a113cbcd5f 100644
--- a/src/nvim/buffer.c
+++ b/src/nvim/buffer.c
@@ -1901,10 +1901,10 @@ int buflist_getfile(int n, linenr_T lnum, int options, int forceit)
     }
   }
 
-  ++RedrawingDisabled;
-  if (getfile(buf->b_fnum, NULL, NULL, (options & GETF_SETMARK),
-          lnum, forceit) <= 0) {
-    --RedrawingDisabled;
+  RedrawingDisabled++;
+  if (GETFILE_SUCCESS(getfile(buf->b_fnum, NULL, NULL,
+                              (options & GETF_SETMARK), lnum, forceit))) {
+    RedrawingDisabled--;
 
     /* cursor is at to BOL and w_cursor.lnum is checked due to getfile() */
     if (!p_sol && col != 0) {
@@ -1915,7 +1915,7 @@ int buflist_getfile(int n, linenr_T lnum, int options, int forceit)
     }
     return OK;
   }
-  --RedrawingDisabled;
+  RedrawingDisabled--;
   return FAIL;
 }
 
diff --git a/src/nvim/buffer.h b/src/nvim/buffer.h
index faeeed121c..d12862a0c6 100644
--- a/src/nvim/buffer.h
+++ b/src/nvim/buffer.h
@@ -17,6 +17,15 @@ enum getf_values {
   GETF_SWITCH  = 0x04, // respect 'switchbuf' settings when jumping
 };
 
+// Return values of getfile()
+enum getf_retvalues {
+  GETFILE_ERROR       = 1,    // normal error
+  GETFILE_NOT_WRITTEN = 2,    // "not written" error
+  GETFILE_SAME_FILE   = 0,    // success, same file
+  GETFILE_OPEN_OTHER  = -1,   // success, opened another file
+  GETFILE_UNUSED      = 8
+};
+
 // Values for buflist_new() flags
 enum bln_values {
   BLN_CURBUF = 1,   // May re-use curbuf for new buffer
diff --git a/src/nvim/buffer_defs.h b/src/nvim/buffer_defs.h
index 50d8c822c1..4fce4ecd22 100644
--- a/src/nvim/buffer_defs.h
+++ b/src/nvim/buffer_defs.h
@@ -41,6 +41,7 @@ typedef struct {
 // for kvec
 #include "nvim/lib/kvec.h"
 
+#define GETFILE_SUCCESS(x)    ((x) <= 0)
 #define MODIFIABLE(buf) (buf->b_p_ma)
 
 /*
diff --git a/src/nvim/ex_cmds.c b/src/nvim/ex_cmds.c
index d58d006dd0..d8aac73b57 100644
--- a/src/nvim/ex_cmds.c
+++ b/src/nvim/ex_cmds.c
@@ -2006,11 +2006,14 @@ static int check_readonly(int *forceit, buf_T *buf)
 
 /*
  * Try to abandon current file and edit a new or existing file.
- * 'fnum' is the number of the file, if zero use ffname/sfname.
+ * "fnum" is the number of the file, if zero use ffname/sfname.
+ * "lnum" is the line number for the cursor in the new file (if non-zero).
  *
- * Return 1 for "normal" error, 2 for "not written" error, 0 for success
- * -1 for successfully opening another file.
- * 'lnum' is the line number for the cursor in the new file (if non-zero).
+ * Return:
+ * GETFILE_ERROR for "normal" error,
+ * GETFILE_NOT_WRITTEN for "not written" error,
+ * GETFILE_SAME_FILE for success
+ * GETFILE_OPEN_OTHER for successfully opening another file.
  */
 int getfile(int fnum, char_u *ffname, char_u *sfname, int setpm, linenr_T lnum, int forceit)
 {
@@ -2018,10 +2021,12 @@ int getfile(int fnum, char_u *ffname, char_u *sfname, int setpm, linenr_T lnum,
   int retval;
   char_u      *free_me = NULL;
 
-  if (text_locked())
-    return 1;
-  if (curbuf_locked())
-    return 1;
+  if (text_locked()) {
+    return GETFILE_ERROR;
+  }
+  if (curbuf_locked()) {
+    return GETFILE_ERROR;
+  }
 
   if (fnum == 0) {
     /* make ffname full path, set sfname */
@@ -2042,7 +2047,7 @@ int getfile(int fnum, char_u *ffname, char_u *sfname, int setpm, linenr_T lnum,
     if (curbufIsChanged()) {
       no_wait_return--;
       EMSG(_(e_nowrtmsg));
-      retval = 2;  // File has been changed.
+      retval = GETFILE_NOT_WRITTEN;     // File has been changed.
       goto theend;
     }
   }
@@ -2056,13 +2061,13 @@ int getfile(int fnum, char_u *ffname, char_u *sfname, int setpm, linenr_T lnum,
     }
     check_cursor_lnum();
     beginline(BL_SOL | BL_FIX);
-    retval = 0;         // it's in the same file
+    retval = GETFILE_SAME_FILE;     // it's in the same file
   } else if (do_ecmd(fnum, ffname, sfname, NULL, lnum,
                      (buf_hide(curbuf) ? ECMD_HIDE : 0)
                      + (forceit ? ECMD_FORCEIT : 0), curwin) == OK) {
-    retval = -1;        // opened another file
+    retval = GETFILE_OPEN_OTHER;    // opened another file
   } else {
-    retval = 1;         // error encountered
+    retval = GETFILE_ERROR;         // error encountered
   }
 
 theend:
diff --git a/src/nvim/search.c b/src/nvim/search.c
index 6c974850ac..27f4389683 100644
--- a/src/nvim/search.c
+++ b/src/nvim/search.c
@@ -1288,9 +1288,9 @@ end_do_search:
  * search_for_exact_line(buf, pos, dir, pat)
  *
  * Search for a line starting with the given pattern (ignoring leading
- * white-space), starting from pos and going in direction dir.	pos will
+ * white-space), starting from pos and going in direction "dir". "pos" will
  * contain the position of the match found.    Blank lines match only if
- * ADDING is set.  if p_ic is set then the pattern must be in lowercase.
+ * ADDING is set.  If p_ic is set then the pattern must be in lowercase.
  * Return OK for success, or FAIL if no line found.
  */
 int search_for_exact_line(buf_T *buf, pos_T *pos, int dir, char_u *pat)
@@ -4595,20 +4595,23 @@ search_line:
             RESET_BINDING(curwin);
           }
           if (depth == -1) {
-            /* match in current file */
+            // match in current file
             if (l_g_do_tagpreview != 0) {
-              if (getfile(0, curwin_save->w_buffer->b_fname,
-                      NULL, TRUE, lnum, FALSE) > 0)
-                break;                  /* failed to jump to file */
-            } else
+              if (!GETFILE_SUCCESS(getfile(0, curwin_save->w_buffer->b_fname,
+                                           NULL, true, lnum, false))) {
+                break;    // failed to jump to file
+              }
+            } else {
               setpcmark();
+            }
             curwin->w_cursor.lnum = lnum;
           } else {
-            if (getfile(0, files[depth].name, NULL, TRUE,
-                    files[depth].lnum, FALSE) > 0)
-              break;                    /* failed to jump to file */
-            /* autocommands may have changed the lnum, we don't
-             * want that here */
+            if (!GETFILE_SUCCESS(getfile(0, files[depth].name, NULL, true,
+                                         files[depth].lnum, false))) {
+              break;    // failed to jump to file
+            }
+            // autocommands may have changed the lnum, we don't
+            // want that here
             curwin->w_cursor.lnum = files[depth].lnum;
           }
         }
diff --git a/src/nvim/tag.c b/src/nvim/tag.c
index 473381a13c..beff89d191 100644
--- a/src/nvim/tag.c
+++ b/src/nvim/tag.c
@@ -2320,7 +2320,7 @@ jumpto_tag (
   char_u      *fname;
   tagptrs_T tagp;
   int retval = FAIL;
-  int getfile_result;
+  int getfile_result = GETFILE_UNUSED;
   int search_options;
   int save_no_hlsearch;
   win_T       *curwin_save = NULL;
@@ -2406,7 +2406,31 @@ jumpto_tag (
 
   // If it was a CTRL-W CTRL-] command split window now.  For ":tab tag"
   // open a new tab page.
-  if (postponed_split || cmdmod.tab != 0) {
+  if (postponed_split && (swb_flags & (SWB_USEOPEN | SWB_USETAB))) {
+    buf_T *const existing_buf = buflist_findname_exp(fname);
+
+    if (existing_buf != NULL) {
+      const win_T *wp = NULL;
+
+      if (swb_flags & SWB_USEOPEN) {
+        wp = buf_jump_open_win(existing_buf);
+      }
+
+      // If 'switchbuf' contains "usetab": jump to first window in any tab
+      // page containing "existing_buf" if one exists
+      if (wp == NULL && (swb_flags & SWB_USETAB)) {
+        wp = buf_jump_open_tab(existing_buf);
+      }
+
+      // We've switched to the buffer, the usual loading of the file must
+      // be skipped.
+      if (wp != NULL) {
+        getfile_result = GETFILE_SAME_FILE;
+      }
+    }
+  }
+  if (getfile_result == GETFILE_UNUSED
+      && (postponed_split || cmdmod.tab != 0)) {
     if (win_split(postponed_split > 0 ? postponed_split : 0,
                   postponed_split_flags) == FAIL) {
       RedrawingDisabled--;
@@ -2423,11 +2447,13 @@ jumpto_tag (
     else
       keep_help_flag = curbuf->b_help;
   }
-  getfile_result = getfile(0, fname, NULL, TRUE, (linenr_T)0, forceit);
-  keep_help_flag = FALSE;
+  if (getfile_result == GETFILE_UNUSED) {
+    getfile_result = getfile(0, fname, NULL, true, (linenr_T)0, forceit);
+  }
+  keep_help_flag = false;
 
-  if (getfile_result <= 0) {            /* got to the right file */
-    curwin->w_set_curswant = TRUE;
+  if (GETFILE_SUCCESS(getfile_result)) {    // got to the right file
+    curwin->w_set_curswant = true;
     postponed_split = 0;
 
     save_secure = secure;
@@ -2545,9 +2571,10 @@ jumpto_tag (
       SET_NO_HLSEARCH(save_no_hlsearch);
     }
 
-    /* Return OK if jumped to another file (at least we found the file!). */
-    if (getfile_result == -1)
+    // Return OK if jumped to another file (at least we found the file!).
+    if (getfile_result == GETFILE_OPEN_OTHER) {
       retval = OK;
+    }
 
     if (retval == OK) {
       /*
diff --git a/src/nvim/testdir/test_tagjump.vim b/src/nvim/testdir/test_tagjump.vim
index d5ce193bc6..dbab8d9e26 100644
--- a/src/nvim/testdir/test_tagjump.vim
+++ b/src/nvim/testdir/test_tagjump.vim
@@ -65,6 +65,48 @@ func Test_duplicate_tagjump()
   call delete('Xfile1')
 endfunc
 
+func Test_tagjump_switchbuf()
+  set tags=Xtags
+  call writefile(["!_TAG_FILE_ENCODING\tutf-8\t//",
+        \ "second\tXfile1\t2",
+        \ "third\tXfile1\t3",],
+        \ 'Xtags')
+  call writefile(['first', 'second', 'third'], 'Xfile1')
+
+  enew | only
+  set switchbuf=
+  stag second
+  call assert_equal(2, winnr('$'))
+  call assert_equal(2, line('.'))
+  stag third
+  call assert_equal(3, winnr('$'))
+  call assert_equal(3, line('.'))
+
+  enew | only
+  set switchbuf=useopen
+  stag second
+  call assert_equal(2, winnr('$'))
+  call assert_equal(2, line('.'))
+  stag third
+  call assert_equal(2, winnr('$'))
+  call assert_equal(3, line('.'))
+
+  enew | only
+  set switchbuf=usetab
+  tab stag second
+  call assert_equal(2, tabpagenr('$'))
+  call assert_equal(2, line('.'))
+  1tabnext | stag third
+  call assert_equal(2, tabpagenr('$'))
+  call assert_equal(3, line('.'))
+
+  tabclose!
+  enew | only
+  call delete('Xfile1')
+  call delete('Xtags')
+  set switchbuf&vim
+endfunc
+
 " Tests for [ CTRL-I and CTRL-W CTRL-I commands
 function Test_keyword_jump()
   call writefile(["#include Xinclude", "",