vim-patch:9.1.0569: fnamemodify() treats ".." and "../" differently (#29673)

Problem:  fnamemodify() treats ".." and "../" differently.
Solution: Expand ".." properly like how "/.." is treated in 8.2.3388.
          (zeertzjq)

closes: vim/vim#15218

https://github.com/vim/vim/commit/1ee7420460768df67ea4bc73467f2d4f8b1555bd

5 files changed, 47 insertions, 22 deletions

diff --git a/src/nvim/path.c b/src/nvim/path.c
index e33e34fff3..adea7ff0f7 100644
--- a/src/nvim/path.c
+++ b/src/nvim/path.c
@@ -2393,9 +2393,13 @@ static int path_to_absolute(const char *fname, char *buf, size_t len, int force)
       p = strrchr(fname, '\\');
     }
 #endif
+    if (p == NULL && strcmp(fname, "..") == 0) {
+      // Handle ".." without path separators.
+      p = fname + 2;
+    }
     if (p != NULL) {
-      if (strcmp(p + 1, "..") == 0) {
-        // for "/path/dir/.." include the "/.."
+      if (vim_ispathsep_nocolon(*p) && strcmp(p + 1, "..") == 0) {
+        // For "/path/dir/.." include the "/..".
         p += 3;
       }
       assert(p >= fname);
diff --git a/test/old/testdir/test_findfile.vim b/test/old/testdir/test_findfile.vim
index 0b241e3466..06d781ed69 100644
--- a/test/old/testdir/test_findfile.vim
+++ b/test/old/testdir/test_findfile.vim
@@ -107,6 +107,9 @@ func Test_findfile()
   let l = findfile('bar', ';../', -1)
   call assert_equal(1, len(l))
   call assert_match('.*/Xfinddir1/Xdir2/Xdir3/bar', l[0])
+  let l = findfile('bar', ';..', -1)
+  call assert_equal(1, len(l))
+  call assert_match('.*/Xfinddir1/Xdir2/Xdir3/bar', l[0])
 
   let l = findfile('bar', ';' . save_dir . '/Xfinddir1/Xdir2/', -1)
   call assert_equal(1, len(l))
@@ -117,6 +120,9 @@ func Test_findfile()
   let l = findfile('bar', ';../../', -1)
   call assert_equal(1, len(l))
   call assert_match('.*/Xfinddir1/Xdir2/Xdir3/bar', l[0])
+  let l = findfile('bar', ';../..', -1)
+  call assert_equal(1, len(l))
+  call assert_match('.*/Xfinddir1/Xdir2/Xdir3/bar', l[0])
 
   let l = findfile('bar', ';' . save_dir . '/Xfinddir1/', -1)
   call assert_equal(2, len(l))
@@ -130,6 +136,10 @@ func Test_findfile()
   call assert_equal(2, len(l))
   call assert_match('.*/Xfinddir1/Xdir2/Xdir3/bar', l[0])
   call assert_match('.*/Xfinddir1/bar',             l[1])
+  let l = findfile('bar', ';../../..', -1)
+  call assert_equal(2, len(l))
+  call assert_match('.*/Xfinddir1/Xdir2/Xdir3/bar', l[0])
+  call assert_match('.*/Xfinddir1/bar',             l[1])
 
   " Test combined downwards and upwards search from Xdir2/.
   cd ../..
diff --git a/test/old/testdir/test_fnamemodify.vim b/test/old/testdir/test_fnamemodify.vim
index 2e6c7b8a1e..f0bc2503b5 100644
--- a/test/old/testdir/test_fnamemodify.vim
+++ b/test/old/testdir/test_fnamemodify.vim
@@ -14,6 +14,8 @@ func Test_fnamemodify()
   call assert_equal($HOME .. "/foo" , fnamemodify('~/foo', ':p'))
   call assert_equal(fnamemodify('.', ':p:h:h:h') .. '/', fnamemodify($HOME .. '/../', ':p'))
   call assert_equal(fnamemodify('.', ':p:h:h:h') .. '/', fnamemodify($HOME .. '/..', ':p'))
+  call assert_equal(fnamemodify('.', ':p:h:h') .. '/', fnamemodify('../', ':p'))
+  call assert_equal(fnamemodify('.', ':p:h:h') .. '/', fnamemodify('..', ':p'))
   call assert_equal('test.out', fnamemodify('test.out', ':.'))
   call assert_equal('a', fnamemodify('../testdir/a', ':.'))
   call assert_equal('~/testdir/test.out', fnamemodify('test.out', ':~'))
diff --git a/test/old/testdir/test_taglist.vim b/test/old/testdir/test_taglist.vim
index 92d6d283ed..fbb682a9b2 100644
--- a/test/old/testdir/test_taglist.vim
+++ b/test/old/testdir/test_taglist.vim
@@ -143,15 +143,15 @@ func Test_tagfiles_stopdir()
   call writefile([], 'Xtagsdir1/Xtags', 'D')
 
   cd Xtagsdir1/
-  let &tags = './Xtags;' .. fnamemodify('./..', ':p')
+  let &tags = './Xtags;' .. fnamemodify('..', ':p')
   call assert_equal(1, len(tagfiles()))
 
   cd Xtagsdir2/
-  let &tags = './Xtags;' .. fnamemodify('./..', ':p')
+  let &tags = './Xtags;' .. fnamemodify('..', ':p')
   call assert_equal(1, len(tagfiles()))
 
   cd Xtagsdir3/
-  let &tags = './Xtags;' .. fnamemodify('./..', ':p')
+  let &tags = './Xtags;' .. fnamemodify('..', ':p')
   call assert_equal(0, len(tagfiles()))
 
   let &tags = './Xtags;../'
@@ -163,6 +163,15 @@ func Test_tagfiles_stopdir()
   cd ..
   call assert_equal(1, len(tagfiles()))
 
+  let &tags = './Xtags;..'
+  call assert_equal(1, len(tagfiles()))
+
+  cd Xtagsdir2/
+  call assert_equal(1, len(tagfiles()))
+
+  cd Xtagsdir3/
+  call assert_equal(0, len(tagfiles()))
+
   set tags&
   call chdir(save_cwd)
 endfunc
diff --git a/test/unit/path_spec.lua b/test/unit/path_spec.lua
index 6f6a80f44e..ffad552a8a 100644
--- a/test/unit/path_spec.lua
+++ b/test/unit/path_spec.lua
@@ -468,8 +468,11 @@ describe('path.c', function()
       eq(OK, result)
     end)
 
-    itp('concatenates directory name if it does not contain a slash', function()
-      local expected = uv.cwd() .. '/..'
+    itp('produces absolute path for .. without a slash', function()
+      local old_dir = uv.cwd()
+      uv.chdir('..')
+      local expected = uv.cwd()
+      uv.chdir(old_dir)
       local filename = '..'
       local buflen = get_buf_len(expected, filename)
       local do_expand = 1
@@ -478,21 +481,18 @@ describe('path.c', function()
       eq(OK, result)
     end)
 
-    itp(
-      'enters given directory (instead of just concatenating the strings) if possible and if path contains a slash',
-      function()
-        local old_dir = uv.cwd()
-        uv.chdir('..')
-        local expected = uv.cwd() .. '/test.file'
-        uv.chdir(old_dir)
-        local filename = '../test.file'
-        local buflen = get_buf_len(expected, filename)
-        local do_expand = 1
-        local buf, result = vim_FullName(filename, buflen, do_expand)
-        eq(expected, ffi.string(buf))
-        eq(OK, result)
-      end
-    )
+    itp('produces absolute path if possible and if path contains a slash', function()
+      local old_dir = uv.cwd()
+      uv.chdir('..')
+      local expected = uv.cwd() .. '/test.file'
+      uv.chdir(old_dir)
+      local filename = '../test.file'
+      local buflen = get_buf_len(expected, filename)
+      local do_expand = 1
+      local buf, result = vim_FullName(filename, buflen, do_expand)
+      eq(expected, ffi.string(buf))
+      eq(OK, result)
+    end)
 
     itp('just copies the path if it is already absolute and force=0', function()
       local absolute_path = '/absolute/path'