vim-patch:8.2.3468: problem with :cd when editing file in non-existent directory

Problem:    Problem with :cd when editing file in non-existent directory. (Yee
            Cheng Chin)
Solution:   Prepend the current directory to get the full path. (closes vim/vim#8903)
c6376c7984

src/nvim/path.c

@@ -2245,11 +2245,17 @@ int path_full_dir_name(char *directory, char *buffer, size_t len)
   }
 
   if (os_chdir(directory) != SUCCESS) {
-    // Do not return immediately since we may be in the wrong directory.
-    retval = FAIL;
-  }
-
-  if (retval == FAIL || os_dirname((char_u *)buffer, len) == FAIL) {
+    // Path does not exist (yet).  For a full path fail,
+    // will use the path as-is.  For a relative path use
+    // the current directory and append the file name.
+    if (path_is_absolute((const char_u *)directory)) {
+      // Do not return immediately since we may be in the wrong directory.
+      retval = FAIL;
+    } else {
+      xstrlcpy(buffer, old_dir, len);
+      append_path(buffer, directory, len);
+    }
+  } else if (os_dirname((char_u *)buffer, len) == FAIL) {
     // Do not return immediately since we are in the wrong directory.
     retval = FAIL;
   }

src/nvim/testdir/test_cd.vim

@@ -215,3 +215,22 @@ func Test_cd_from_non_existing_dir()
   cd -
   call assert_equal(saveddir, getcwd())
 endfunc
+
+func Test_cd_unknown_dir()
+  call mkdir('Xa')
+  cd Xa
+  call writefile(['text'], 'Xb.txt')
+  edit Xa/Xb.txt
+  let first_buf = bufnr()
+  cd ..
+  edit
+  call assert_equal(first_buf, bufnr())
+  edit Xa/Xb.txt
+  call assert_notequal(first_buf, bufnr())
+
+  bwipe!
+  exe "bwipe! " .. first_buf
+  call delete('Xa', 'rf')
+endfunc
+
+" vim: shiftwidth=2 sts=2 expandtab

test/functional/legacy/fnamemodify_spec.lua

@@ -29,7 +29,7 @@ describe('filename modifiers', function()
         call assert_equal('test.out', fnamemodify('test.out', ':.'))
         call assert_equal('../testdir/a', fnamemodify('../testdir/a', ':.'))
         call assert_equal(fnamemodify(tmpdir, ':~').'/test.out', fnamemodify('test.out', ':~'))
-        call assert_equal('../testdir/a', fnamemodify('../testdir/a', ':~'))
+        call assert_equal(fnamemodify(tmpdir, ':~').'/../testdir/a', fnamemodify('../testdir/a', ':~'))
         call assert_equal('a', fnamemodify('../testdir/a', ':t'))
         call assert_equal('', fnamemodify('.', ':p:t'))
         call assert_equal('test.out', fnamemodify('test.out', ':p:t'))

test/functional/lua/uri_spec.lua

@@ -143,8 +143,8 @@ describe('URI methods', function()
       end)
 
       it('uri_to_fname returns non-file scheme URI without authority unchanged', function()
-        eq('zipfile:/path/to/archive.zip%3A%3Afilename.txt', exec_lua [[
-          return vim.uri_to_fname('zipfile:/path/to/archive.zip%3A%3Afilename.txt')
+        eq('zipfile:///path/to/archive.zip%3A%3Afilename.txt', exec_lua [[
+          return vim.uri_to_fname('zipfile:///path/to/archive.zip%3A%3Afilename.txt')
         ]])
       end)
     end)
@@ -186,7 +186,7 @@ describe('URI methods', function()
     end)
 
     it('uri_to_bufnr & uri_from_bufnr returns original uri for non-file uris without authority', function()
-      local uri = 'zipfile:/path/to/archive.zip%3A%3Afilename.txt'
+      local uri = 'zipfile:///path/to/archive.zip%3A%3Afilename.txt'
       local test_case = string.format([[
         local uri = '%s'
         return vim.uri_from_bufnr(vim.uri_to_bufnr(uri))

test/unit/path_spec.lua

@@ -54,15 +54,21 @@ describe('path.c', function()
       eq(lfs.currentdir(), (ffi.string(buffer)))
     end)
 
-    itp('fails if the given directory does not exist', function()
-      eq(FAIL, path_full_dir_name('does_not_exist', buffer, length))
-    end)
-
     itp('works with a normal relative dir', function()
       local result = path_full_dir_name('unit-test-directory', buffer, length)
       eq(lfs.currentdir() .. '/unit-test-directory', (ffi.string(buffer)))
       eq(OK, result)
     end)
+
+    itp('works with a non-existing relative dir', function()
+      local result = path_full_dir_name('does-not-exist', buffer, length)
+      eq(lfs.currentdir() .. '/does-not-exist', (ffi.string(buffer)))
+      eq(OK, result)
+    end)
+
+    itp('fails with a non-existing absolute dir', function()
+      eq(FAIL, path_full_dir_name('/does_not_exist', buffer, length))
+    end)
   end)
 
   describe('path_full_compare', function()