vim-patch:8.2.3780: ":cd" works differently on MS-Windows

Problem:    ":cd" works differently on MS-Windows.
Solution:   Add the 'cdhome' option. (closes vim/vim#9324)
29f3a45915

runtime/doc/editing.txt

@@ -1253,10 +1253,12 @@ working directory.  If a local working directory (tab or window) does not
 exist, the next-higher scope in the hierarchy applies.
 
 							*:cd* *E747* *E472*
-:cd[!]			On non-Unix systems: Print the current directory
+:cd[!]			On non-Unix systems when 'cdhome' is off: Print the
-			name.  On Unix systems: Change the current directory
+			current directory name.
-			to the home directory.  Use |:pwd| to print the
+			Otherwise: Change the current directory to the home
-			current directory on all systems.
+			directory.  Clear any window-local directory.
+			Use |:pwd| to print the current directory on all
+			systems.
 
 :cd[!] {path}		Change the current directory to {path}.
 			If {path} is relative, it is searched for in the

runtime/doc/quickref.txt

@@ -629,6 +629,7 @@ Short explanation of each option:		*option-list*
 'buflisted'	  'bl'	    whether the buffer shows up in the buffer list
 'buftype'	  'bt'	    special type of buffer
 'casemap'	  'cmp'     specifies how case of letters is changed
+'cdhome'	  'cdh'	    change directory to the home directory by ":cd"
 'cdpath'	  'cd'	    list of directories searched with ":cd"
 'cedit'			    key used to open the command-line window
 'charconvert'	  'ccv'     expression for character encoding conversion

runtime/optwin.vim

@@ -261,6 +261,10 @@ call <SID>OptionG("sect", &sect)
 call append("$", "path\tlist of directory names used for file searching")
 call append("$", "\t(global or local to buffer)")
 call <SID>OptionG("pa", &pa)
+if exists("+cdhome")
+  call <SID>AddOption("cdhome", "change directory to the home directory by :cd")
+  call <SID>BinOptionG("cdh", &cdh)
+endif
 call append("$", "cdpath\tlist of directory names used for :cd")
 call <SID>OptionG("cd", &cd)
 if exists("+autochdir")

src/nvim/ex_docmd.c

@@ -7807,14 +7807,17 @@ bool changedir_func(char_u *new_dir, CdScope scope)
     prev_dir = pdir;
   }
 
+  // For UNIX ":cd" means: go to home directory.
+  // On other systems too if 'cdhome' is set.
 #if defined(UNIX)
-  // On Unix ":cd" means: go to home directory.
   if (*new_dir == NUL) {
+#else
+  if (*new_dir == NUL && p_cdh) {
+#endif
     // Use NameBuff for home directory name.
     expand_env((char_u *)"$HOME", NameBuff, MAXPATHL);
     new_dir = NameBuff;
   }
-#endif
 
   bool dir_differs = new_dir == NULL || pdir == NULL
     || pathcmp((char *)pdir, (char *)new_dir, -1) != 0;
@@ -7834,9 +7837,9 @@ void ex_cd(exarg_T *eap)
 {
   char_u *new_dir;
   new_dir = eap->arg;
-#if !defined(UNIX) && !defined(VMS)
+#if !defined(UNIX)
-  // for non-UNIX ":cd" means: print current directory
+  // for non-UNIX ":cd" means: print current directory unless 'cdhome' is set
-  if (*new_dir == NUL) {
+  if (*new_dir == NUL && !p_cdh) {
     ex_pwd(NULL);
   } else
 #endif

src/nvim/option_defs.h

@@ -743,6 +743,7 @@ EXTERN int p_write;             // 'write'
 EXTERN int p_wa;                // 'writeany'
 EXTERN int p_wb;                // 'writebackup'
 EXTERN long p_wd;               // 'writedelay'
+EXTERN int p_cdh;               // 'cdhome'
 
 EXTERN int p_force_on;          ///< options that cannot be turned off.
 EXTERN int p_force_off;         ///< options that cannot be turned on.

src/nvim/options.lua

@@ -274,6 +274,14 @@ return {
       varname='p_cmp',
       defaults={if_true="internal,keepascii"}
     },
+    {
+      full_name='cdhome', abbreviation='cdh',
+      short_desc=N_("change directory to the home directory by :cd"),
+      type='bool', scope={'global'},
+      secure=true,
+      varname='p_cdh',
+      defaults={if_true=false}
+    },
     {
       full_name='cdpath', abbreviation='cd',
       short_desc=N_("list of directories searched with \":cd\""),

src/nvim/testdir/runtest.vim

@@ -64,6 +64,9 @@ if has('reltime')
   let s:start_time = reltime()
 endif
 
+" Always use forward slashes.
+set shellslash
+
 " Common with all tests on all systems.
 source setup.vim
 
@@ -104,9 +107,6 @@ lang mess C
 " Nvim: append runtime from build dir, which contains the generated doc/tags.
 let &runtimepath .= ','.expand($BUILD_DIR).'/runtime/'
 
-" Always use forward slashes.
-set shellslash
-
 let s:t_bold = &t_md
 let s:t_normal = &t_me
 if has('win32')

src/nvim/testdir/test_options.vim

@@ -732,4 +732,25 @@ func Test_opt_reset_scroll()
   call delete('Xscroll')
 endfunc
 
+" Test for the 'cdhome' option
+func Test_opt_cdhome()
+  if has('unix') || has('vms')
+    throw 'Skipped: only works on non-Unix'
+  endif
+
+  set cdhome&
+  call assert_equal(0, &cdhome)
+  set cdhome
+
+  " This paragraph is copied from Test_cd_no_arg().
+  let path = getcwd()
+  cd
+  call assert_equal($HOME, getcwd())
+  call assert_notequal(path, getcwd())
+  exe 'cd ' .. fnameescape(path)
+  call assert_equal(path, getcwd())
+
+  set cdhome&
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab