fix(snippet): correct indent with newline

Problem: snippet newline use before line indent after expand.

Solution: it should level + 1.

2 files changed, 32 insertions, 5 deletions

diff --git a/runtime/lua/vim/snippet.lua b/runtime/lua/vim/snippet.lua
index 09b7576d97..a660d6f301 100644
--- a/runtime/lua/vim/snippet.lua
+++ b/runtime/lua/vim/snippet.lua
@@ -446,14 +446,18 @@ function M.expand(input)
       base_indent = base_indent .. (snippet_lines[#snippet_lines]:match('(^%s*)%S') or '') --- @type string
     end
 
+    local shiftwidth = vim.fn.shiftwidth()
+    local curbuf = vim.api.nvim_get_current_buf()
+    local expandtab = vim.bo[curbuf].expandtab
     local lines = vim.iter.map(function(i, line)
       -- Replace tabs by spaces.
-      if vim.o.expandtab then
-        line = line:gsub('\t', (' '):rep(vim.fn.shiftwidth())) --- @type string
+      if expandtab then
+        line = line:gsub('\t', (' '):rep(shiftwidth)) --- @type string
       end
       -- Add the base indentation.
       if i > 1 then
-        line = base_indent .. line
+        line = #line ~= 0 and base_indent .. line
+          or (expandtab and (' '):rep(shiftwidth) or '\t'):rep(vim.fn.indent('.') / shiftwidth + 1)
       end
       return line
     end, ipairs(text_to_lines(text)))
diff --git a/test/functional/lua/snippet_spec.lua b/test/functional/lua/snippet_spec.lua
index e981bc6261..d31b8cc7d5 100644
--- a/test/functional/lua/snippet_spec.lua
+++ b/test/functional/lua/snippet_spec.lua
@@ -5,6 +5,7 @@ local clear = helpers.clear
 local eq = helpers.eq
 local exec_lua = helpers.exec_lua
 local feed = helpers.feed
+local api = helpers.api
 local fn = helpers.fn
 local matches = helpers.matches
 local pcall_err = helpers.pcall_err
@@ -230,7 +231,7 @@ describe('vim.snippet', function()
   end)
 
   it('updates snippet state when built-in completion menu is visible', function()
-    test_expand_success({ '$1 = function($2)\n$3\nend' }, { ' = function()', '', 'end' })
+    test_expand_success({ '$1 = function($2)\nend' }, { ' = function()', 'end' })
     -- Show the completion menu.
     feed('<C-n>')
     -- Make sure no item is selected.
@@ -238,6 +239,28 @@ describe('vim.snippet', function()
     -- Jump forward (the 2nd tabstop).
     exec_lua('vim.snippet.jump(1)')
     feed('foo')
-    eq({ ' = function(foo)', '', 'end' }, buf_lines(0))
+    eq({ ' = function(foo)', 'end' }, buf_lines(0))
+  end)
+
+  it('correctly indents with newlines', function()
+    local curbuf = api.nvim_get_current_buf()
+    test_expand_success(
+      { 'function($2)\n$3\nend' },
+      { 'function()', '  ', 'end' },
+      [[
+      vim.opt.sw = 2
+      vim.opt.expandtab = true
+    ]]
+    )
+    api.nvim_buf_set_lines(curbuf, 0, -1, false, {})
+    test_expand_success(
+      { 'func main() {\n$1\n}' },
+      { 'func main() {', '\t', '}' },
+      [[
+      vim.opt.sw = 4
+      vim.opt.ts = 4
+      vim.opt.expandtab = false
+    ]]
+    )
   end)
 end)