fix(api): memory leaks in vim.api.nvim_*get_option #32390

Problem: `get_option_value` returns caller owned `Object`s but the
corresponding C apis do not marked `FUNC_API_RET_ALLOC` properly.

Solution: add `FUNC_API_RET_ALLOC` to the C apis.

2 files changed, 15 insertions, 1 deletions

diff --git a/src/nvim/api/deprecated.c b/src/nvim/api/deprecated.c
index 1d81b21be6..2f29ed38ef 100644
--- a/src/nvim/api/deprecated.c
+++ b/src/nvim/api/deprecated.c
@@ -633,6 +633,7 @@ void nvim_set_option(uint64_t channel_id, String name, Object value, Error *err)
 Object nvim_get_option(String name, Error *err)
   FUNC_API_SINCE(1)
   FUNC_API_DEPRECATED_SINCE(11)
+  FUNC_API_RET_ALLOC
 {
   return get_option_from(NULL, kOptScopeGlobal, name, err);
 }
@@ -647,6 +648,7 @@ Object nvim_get_option(String name, Error *err)
 Object nvim_buf_get_option(Buffer buffer, String name, Error *err)
   FUNC_API_SINCE(1)
   FUNC_API_DEPRECATED_SINCE(11)
+  FUNC_API_RET_ALLOC
 {
   buf_T *buf = find_buffer_by_handle(buffer, err);
 
@@ -689,6 +691,7 @@ void nvim_buf_set_option(uint64_t channel_id, Buffer buffer, String name, Object
 Object nvim_win_get_option(Window window, String name, Error *err)
   FUNC_API_SINCE(1)
   FUNC_API_DEPRECATED_SINCE(11)
+  FUNC_API_RET_ALLOC
 {
   win_T *win = find_window_by_handle(window, err);
 
@@ -728,7 +731,7 @@ void nvim_win_set_option(uint64_t channel_id, Window window, String name, Object
 /// @param       name       The option name.
 /// @param[out]  err        Details of an error that may have occurred.
 ///
-/// @return  the option value.
+/// @return  the option value. Must be freed by caller.
 static Object get_option_from(void *from, OptScope scope, String name, Error *err)
 {
   VALIDATE_S(name.size > 0, "option name", "<empty>", {
diff --git a/test/functional/api/deprecated_spec.lua b/test/functional/api/deprecated_spec.lua
index 2efcfda873..d967bfa743 100644
--- a/test/functional/api/deprecated_spec.lua
+++ b/test/functional/api/deprecated_spec.lua
@@ -18,4 +18,15 @@ describe('deprecated', function()
       n.api.nvim_notify('hello world', 4, {})
     end)
   end)
+
+  describe('nvim_*get_option functions', function()
+    it('does not leak memory', function()
+      -- String opts caused memory leaks in these functions in Github#32361
+      n.exec_lua([[
+        vim.api.nvim_get_option('rtp')
+        vim.api.nvim_win_get_option(vim.api.nvim_get_current_win(), 'foldmethod')
+        vim.api.nvim_buf_get_option(0, 'fileformat')
+      ]])
+    end)
+  end)
 end)