DirChanged: trigger when switching scopes

Closes #6054

src/nvim/ex_docmd.c

@@ -6962,7 +6962,6 @@ void post_chdir(CdScope scope)
 
   char curdir[MAXPATHL];
   if (os_dirname((char_u *)curdir, MAXPATHL) != OK) {
-    EMSG2(_(e_intern2), "post_chdir()");
     return;
   }
   switch (scope) {
@@ -6981,7 +6980,7 @@ void post_chdir(CdScope scope)
     assert(false);
   }
 
-  shorten_fnames(TRUE);
+  shorten_fnames(true);
   do_autocmd_dirchanged(curdir, scope);
 }
 

src/nvim/file_search.c

@@ -1550,10 +1550,11 @@ void do_autocmd_dirchanged(char *new_dir, CdScope scope)
   }
 
   dict_add_nr_str(dict, "scope", 0L, (char_u *)buf);
-  dict_add_nr_str(dict, "cwd",   0L, new_dir);
+  dict_add_nr_str(dict, "cwd",   0L, (char_u *)new_dir);
   dict_set_keys_readonly(dict);
 
-  apply_autocmds(EVENT_DIRCHANGED, (char_u *)buf, new_dir, false, NULL);
+  apply_autocmds(EVENT_DIRCHANGED, (char_u *)buf, (char_u *)new_dir, false,
+                 NULL);
 
   dict_clear(dict);
 
@@ -1572,7 +1573,7 @@ int vim_chdirfile(char_u *fname)
   if (os_chdir((char *)dir) != 0) {
     return FAIL;
   }
-  do_autocmd_dirchanged(dir, kCdScopeWindow);
+  do_autocmd_dirchanged((char *)dir, kCdScopeWindow);
 
   return OK;
 }

src/nvim/memory.c

@@ -475,6 +475,13 @@ void *xmemdup(const void *data, size_t len)
   return memcpy(xmalloc(len), data, len);
 }
 
+/// Returns true if strings `a` and `b` are equal. Arguments may be NULL.
+bool strequal(const char *a, const char *b)
+  FUNC_ATTR_PURE FUNC_ATTR_WARN_UNUSED_RESULT
+{
+  return (a == NULL && b == NULL) || (a && b && strcmp(a, b) == 0);
+}
+
 /*
  * Avoid repeating the error message many times (they take 1 second each).
  * Did_outofmem_msg is reset when a character is read.

src/nvim/window.c

@@ -3616,28 +3616,38 @@ static void win_enter_ext(win_T *wp, bool undo_sync, int curwin_invalid,
     curwin->w_cursor.coladd = 0;
   changed_line_abv_curs();      /* assume cursor position needs updating */
 
-  // The new directory is either the local directory of the window, tab or NULL.
-  char_u *new_dir = curwin->w_localdir
-                    ? curwin->w_localdir : curtab->tp_localdir;
+  // New directory is either the local directory of the window, tab or NULL.
+  char *new_dir = (char *)(curwin->w_localdir
+                           ? curwin->w_localdir : curtab->tp_localdir);
+
+  char cwd[MAXPATHL];
+  if (os_dirname((char_u *)cwd, MAXPATHL) != OK) {
+    cwd[0] = NUL;
+  }
 
   if (new_dir) {
     // Window/tab has a local directory: Save current directory as global
-    // directory (unless that was done already) and change to the local
-    // directory.
+    // (unless that was done already) and change to the local directory.
     if (globaldir == NULL) {
-      char_u cwd[MAXPATHL];
-
-      if (os_dirname(cwd, MAXPATHL) == OK) {
-        globaldir = vim_strsave(cwd);
+      if (cwd[0] != NUL) {
+        globaldir = (char_u *)xstrdup(cwd);
       }
     }
-    if (os_chdir((char *)new_dir) == 0) {
+    if (os_chdir(new_dir) == 0) {
+      if (!p_acd && !strequal(new_dir, cwd)) {
+        do_autocmd_dirchanged(new_dir, curwin->w_localdir
+                              ? kCdScopeWindow : kCdScopeTab);
+      }
       shorten_fnames(true);
     }
   } else if (globaldir != NULL) {
-    /* Window doesn't have a local directory and we are not in the global
-     * directory: Change to the global directory. */
-    ignored = os_chdir((char *)globaldir);
+    // Window doesn't have a local directory and we are not in the global
+    // directory: Change to the global directory.
+    if (os_chdir((char *)globaldir) == 0) {
+      if (!p_acd && !strequal((char *)globaldir, cwd)) {
+        do_autocmd_dirchanged((char *)globaldir, kCdScopeGlobal);
+      }
+    }
     xfree(globaldir);
     globaldir = NULL;
     shorten_fnames(TRUE);

test/functional/autocmd/dirchanged_spec.lua

@@ -109,6 +109,34 @@ describe('autocmd DirChanged', function()
     eq({cwd=dirs[2], scope='window'}, eval('g:event'))
   end)
 
+  it("is triggered by switching to win/tab with different CWD #6054", function()
+    command('lcd '..dirs[3])            -- window 3
+    command('split '..dirs[2]..'/foo')  -- window 2
+    command('lcd '..dirs[2])
+    command('split '..dirs[1]..'/bar')  -- window 1
+    command('lcd '..dirs[1])
+
+    command('2wincmd w')                -- window 2
+    eq({cwd=dirs[2], scope='window'}, eval('g:event'))
+
+    eq(4, eval('g:cdcount'))
+    command('tabnew')                   -- tab 2 (tab-local CWD)
+    eq(4, eval('g:cdcount'))            -- same CWD, no DirChanged event
+    command('tcd '..dirs[3])
+    command('tabnext')                  -- tab 1 (no tab-local CWD)
+    eq({cwd=dirs[2], scope='window'}, eval('g:event'))
+    command('tabnext')                  -- tab 2
+    eq({cwd=dirs[3], scope='tab'}, eval('g:event'))
+    eq(7, eval('g:cdcount'))
+
+    command('tabnext')                  -- tab 1
+    command('3wincmd w')                -- window 3
+    eq(9, eval('g:cdcount'))
+    command('tabnext')                  -- tab 2 (has the *same* CWD)
+    eq(9, eval('g:cdcount'))            -- same CWD, no DirChanged event
+
+  end)
+
   it('is triggered by nvim_set_current_dir()', function()
     request('nvim_set_current_dir', dirs[1])
     eq({cwd=dirs[1], scope='global'}, eval('g:event'))