fix(lsp): set tagstack on jump via goto methods

Follow up to https://github.com/neovim/neovim/pull/30877
Fixes https://github.com/neovim/neovim/issues/30926

runtime/lua/vim/lsp/buf.lua

@@ -54,6 +54,9 @@ local function get_locations(method, opts)
     return
   end
   local win = api.nvim_get_current_win()
+  local from = vim.fn.getpos('.')
+  from[1] = bufnr
+  local tagname = vim.fn.expand('<cword>')
   local remaining = #clients
 
   ---@type vim.quickfix.entry[]
@@ -89,6 +92,13 @@ local function get_locations(method, opts)
       if #all_items == 1 then
         local item = all_items[1]
         local b = item.bufnr or vim.fn.bufadd(item.filename)
+
+        -- Save position in jumplist
+        vim.cmd("normal! m'")
+        -- Push a new item into tagstack
+        local tagstack = { { tagname = tagname, from = from } }
+        vim.fn.settagstack(vim.fn.win_getid(win), { items = tagstack }, 't')
+
         vim.bo[b].buflisted = true
         local w = opts.reuse_win and vim.fn.win_findbuf(b)[1] or win
         api.nvim_win_set_buf(w, b)

test/functional/plugin/lsp_spec.lua

@@ -5107,10 +5107,15 @@ describe('LSP', function()
         return {
           cursor = vim.api.nvim_win_get_cursor(win),
           messages = server.messages,
+          tagstack = vim.fn.gettagstack(win),
         }
       end)
       eq('textDocument/definition', result.messages[3].method)
       eq({ 1, 0 }, result.cursor)
+      eq(1, #result.tagstack.items)
+      eq('x', result.tagstack.items[1].tagname)
+      eq(3, result.tagstack.items[1].from[2])
+      eq(7, result.tagstack.items[1].from[3])
     end)
     it('merges results from multiple servers', function()
       exec_lua(create_server_definition)