vim-patch:9.2.0020: Wrong shortened buffer after :cd with duplicate slashes (#37955)

Problem:  Wrong shortened buffer name after :cd with duplicate slashes.
Solution: Skip over multiple consecutive path separators (zeertzjq).

related: neovim/neovim#37080
closes:  vim/vim#19444

f245e17ac7

N/A patches:
vim-patch:9.0.1859: heap-use-after-free in bt_normal()
vim-patch:9.2.0022: bt_quickfix() is slow

src/nvim/path.c

@@ -2121,7 +2121,10 @@ char *path_shorten_fname(char *full_path, char *dir_name)
     return NULL;
   }
 
-  return p + 1;
+  do {
+    p++;
+  } while (vim_ispathsep_nocolon(*p));
+  return p;
 }
 
 /// Invoke expand_wildcards() for one pattern

test/old/testdir/test_cd.vim

@@ -414,4 +414,15 @@ func Test_cd_symlinks()
   call chdir(savedir)
 endfunc
 
+func Test_cd_shorten_bufname_with_duplicate_slashes()
+  let savedir = getcwd()
+  call mkdir('Xexistingdir', 'R')
+  new Xexistingdir//foo/bar
+  cd Xexistingdir
+  call assert_equal('foo/bar', bufname('%'))
+
+  call chdir(savedir)
+  bwipe!
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab

test/unit/path_spec.lua

@@ -299,6 +299,11 @@ describe('path.c', function()
       local full = to_cstr('some/very/long/directory/file.txt')
       local dir = to_cstr('some/very/long')
       eq('directory/file.txt', (ffi.string(cimp.path_shorten_fname(full, dir))))
+      -- Also works with duplicate slashes. #37080
+      full = to_cstr('some/very/long//directory/file.txt')
+      eq('directory/file.txt', (ffi.string(cimp.path_shorten_fname(full, dir))))
+      full = to_cstr('some/very/long///directory/file.txt')
+      eq('directory/file.txt', (ffi.string(cimp.path_shorten_fname(full, dir))))
     end)
   end)
 end)