API: make nvim_win_set_option() set window-global, not buffer-local #9110

NB: the `!(flags & SOPT_GLOBAL)` exception is for 'statusline'.
Because `:set statusline=...` sets the global value for _all_ windows,
`:setlocal` is the best we can do there. This is a one-of-a-kind option
that doesn't work like any other option.

3 files changed, 13 insertions, 3 deletions

diff --git a/src/nvim/api/private/helpers.c b/src/nvim/api/private/helpers.c
index 2e4874d7c6..26f388ae7e 100644
--- a/src/nvim/api/private/helpers.c
+++ b/src/nvim/api/private/helpers.c
@@ -394,7 +394,9 @@ void set_option_to(uint64_t channel_id, void *to, int type,
   current_SID = channel_id == LUA_INTERNAL_CALL ? SID_LUA : SID_API_CLIENT;
   current_channel_id = channel_id;
 
-  const int opt_flags = (type == SREQ_GLOBAL) ? OPT_GLOBAL : OPT_LOCAL;
+  const int opt_flags = (type == SREQ_WIN && !(flags & SOPT_GLOBAL))
+                        ? 0 : (type == SREQ_GLOBAL)
+                              ? OPT_GLOBAL : OPT_LOCAL;
   set_option_value_for(name.data, numval, stringval,
                        opt_flags, type, to, err);
 
diff --git a/test/functional/api/window_spec.lua b/test/functional/api/window_spec.lua
index 9af1bdb93b..3bc53cfc83 100644
--- a/test/functional/api/window_spec.lua
+++ b/test/functional/api/window_spec.lua
@@ -212,10 +212,18 @@ describe('API/win', function()
     it('works', function()
       curwin('set_option', 'colorcolumn', '4,3')
       eq('4,3', curwin('get_option', 'colorcolumn'))
+      command("set modified hidden")
+      command("enew") -- edit new buffer, window option is preserved
+      eq('4,3', curwin('get_option', 'colorcolumn'))
+
       -- global-local option
       curwin('set_option', 'statusline', 'window-status')
       eq('window-status', curwin('get_option', 'statusline'))
       eq('', nvim('get_option', 'statusline'))
+      command("set modified")
+      command("enew") -- global-local: not preserved in new buffer
+      eq({false, "Failed to get value for option 'statusline'"}, meth_pcall(curwin, 'get_option', 'statusline'))
+      eq('', eval('&l:statusline')) -- confirm local value was not copied
     end)
   end)
 
diff --git a/test/functional/eval/buf_functions_spec.lua b/test/functional/eval/buf_functions_spec.lua
index c0e264d4c9..380ccfb5d5 100644
--- a/test/functional/eval/buf_functions_spec.lua
+++ b/test/functional/eval/buf_functions_spec.lua
@@ -228,9 +228,9 @@ describe('getbufvar() function', function()
     eq(0, funcs.getbufvar(1, '&g:number'))
     command('new')
     -- But with window-local options it probably does not what you expect
-    curwinmeths.set_option('number', true)
+    command("setl number")
     -- (note that current window’s buffer is 2, but getbufvar() receives 1)
-    eq(2, bufmeths.get_number(curwinmeths.get_buf()))
+    eq({id=2}, curwinmeths.get_buf())
     eq(1, funcs.getbufvar(1, '&number'))
     eq(1, funcs.getbufvar(1, '&l:number'))
     -- You can get global value though, if you find this useful.