5 files changed, 68 insertions, 19 deletions
diff --git a/src/nvim/eval.c b/src/nvim/eval.c
index 5ef2a8772e..df677a3a13 100644
--- a/src/nvim/eval.c
+++ b/src/nvim/eval.c
@@ -6328,8 +6328,12 @@ call_func(
   }
 
 
-  /* execute the function if no errors detected and executing */
-  if (evaluate && error == ERROR_NONE) {
+  // Execute the function if executing and no errors were detected.
+  if (!evaluate) {
+    // Not evaluating, which means the return value is unknown.  This
+    // matters for giving error messages.
+    rettv->v_type = VAR_UNKNOWN;
+  } else if (error == ERROR_NONE) {
     char_u *rfname = fname;
 
     /* Ignore "g:" before a function name. */
diff --git a/src/nvim/lua/executor.c b/src/nvim/lua/executor.c
index 93069893cf..72b97736fc 100644
--- a/src/nvim/lua/executor.c
+++ b/src/nvim/lua/executor.c
@@ -24,6 +24,10 @@
 #include "nvim/undo.h"
 #include "nvim/ascii.h"
 
+#ifdef WIN32
+#include "nvim/os/os.h"
+#endif
+
 #include "nvim/lua/executor.h"
 #include "nvim/lua/converter.h"
 
@@ -118,6 +122,14 @@ static int nlua_state_init(lua_State *const lstate) FUNC_ATTR_NONNULL_ALL
   lua_setfield(lstate, -2, "debug");
   lua_pop(lstate, 1);
 
+#ifdef WIN32
+  // os.getenv
+  lua_getglobal(lstate, "os");
+  lua_pushcfunction(lstate, &nlua_getenv);
+  lua_setfield(lstate, -2, "getenv");
+  lua_pop(lstate, 1);
+#endif
+
   // vim
   if (luaL_dostring(lstate, (char *)&vim_module[0])) {
     nlua_error(lstate, _("E5106: Error while creating vim module: %.*s"));
@@ -297,7 +309,7 @@ nlua_print_error:
   return 0;
 }
 
-/// debug.debug implementation: interaction with user while debugging
+/// debug.debug: interaction with user while debugging.
 ///
 /// @param  lstate  Lua interpreter state.
 int nlua_debug(lua_State *lstate)
@@ -337,6 +349,19 @@ int nlua_debug(lua_State *lstate)
   return 0;
 }
 
+#ifdef WIN32
+/// os.getenv: override os.getenv to maintain coherency. #9681
+///
+/// uv_os_setenv uses SetEnvironmentVariableW which does not update _environ.
+///
+/// @param  lstate  Lua interpreter state.
+static int nlua_getenv(lua_State *lstate)
+{
+  lua_pushstring(lstate, os_getenv(luaL_checkstring(lstate, 1)));
+  return 1;
+}
+#endif
+
 /// Evaluate lua string
 ///
 /// Used for luaeval().
diff --git a/src/nvim/os/env.c b/src/nvim/os/env.c
index e7bfbc8240..7d1021962c 100644
--- a/src/nvim/os/env.c
+++ b/src/nvim/os/env.c
@@ -151,25 +151,36 @@ int os_unsetenv(const char *name)
 char *os_getenvname_at_index(size_t index)
 {
 #ifdef _WIN32
-  // Check if index is inside the environ array and is not the last element.
-  for (size_t i = 0; i <= index; i++) {
-    if (_wenviron[i] == NULL) {
-      return NULL;
-    }
-  }
-  wchar_t *utf16_str = _wenviron[index];
-  char *utf8_str;
-  int conversion_result = utf16_to_utf8(utf16_str, &utf8_str);
-  if (conversion_result != 0) {
-    EMSG2("utf16_to_utf8 failed: %d", conversion_result);
+  wchar_t *env = GetEnvironmentStringsW();
+  if (!env) {
     return NULL;
   }
-  size_t namesize = 0;
-  while (utf8_str[namesize] != '=' && utf8_str[namesize] != NUL) {
-    namesize++;
+  char *name = NULL;
+  size_t current_index = 0;
+  // GetEnvironmentStringsW() result has this format:
+  //    var1=value1\0var2=value2\0...varN=valueN\0\0
+  for (wchar_t *it = env; *it != L'\0' || *(it + 1) != L'\0'; it++) {
+    if (index == current_index) {
+      char *utf8_str;
+      int conversion_result = utf16_to_utf8(it, &utf8_str);
+      if (conversion_result != 0) {
+        EMSG2("utf16_to_utf8 failed: %d", conversion_result);
+        break;
+      }
+      size_t namesize = 0;
+      while (utf8_str[namesize] != '=' && utf8_str[namesize] != NUL) {
+        namesize++;
+      }
+      name = (char *)vim_strnsave((char_u *)utf8_str, namesize);
+      xfree(utf8_str);
+      break;
+    }
+    if (*it == L'\0') {
+      current_index++;
+    }
   }
-  char *name = (char *)vim_strnsave((char_u *)utf8_str, namesize);
-  xfree(utf8_str);
+
+  FreeEnvironmentStringsW(env);
   return name;
 #else
 # if defined(HAVE__NSGETENVIRON)
diff --git a/src/nvim/testdir/test_lambda.vim b/src/nvim/testdir/test_lambda.vim
index ada25da4a8..bc7817cef8 100644
--- a/src/nvim/testdir/test_lambda.vim
+++ b/src/nvim/testdir/test_lambda.vim
@@ -291,3 +291,9 @@ func Test_named_function_closure()
   call garbagecollect()
   call assert_equal(14, s:Abar())
 endfunc
+
+func Test_lambda_with_index()
+  let List = {x -> [x]}
+  let Extract = {-> function(List, ['foobar'])()[0]}
+  call assert_equal('foobar', Extract())
+endfunc
diff --git a/src/nvim/testdir/test_timers.vim b/src/nvim/testdir/test_timers.vim
index 62ddad5dce..5a0939a6a1 100644
--- a/src/nvim/testdir/test_timers.vim
+++ b/src/nvim/testdir/test_timers.vim
@@ -47,6 +47,9 @@ func Test_repeat_many()
   call timer_stopall()
   let g:val = 0
   let timer = timer_start(50, 'MyHandler', {'repeat': -1})
+  if has('mac')
+    sleep 200m
+  endif
   sleep 200m
   call timer_stop(timer)
   call assert_inrange((has('mac') ? 1 : 2), 4, g:val)