vim-patch:8.2.3705: cannot pass a lambda name to function() or funcref()

Problem:    Cannot pass a lambda name to function() or funcref(). (Yegappan
            Lakshmanan)
Solution:   Handle a lambda name differently.

https://github.com/vim/vim/commit/eba3b7f6645c8f856132b4c06a009a3b0a44e21c

Co-authored-by: Bram Moolenaar <Bram@vim.org>

3 files changed, 31 insertions, 11 deletions

diff --git a/src/nvim/eval.c b/src/nvim/eval.c
index fe4ae92834..c983388450 100644
--- a/src/nvim/eval.c
+++ b/src/nvim/eval.c
@@ -5029,9 +5029,8 @@ void common_function(typval_T *argvars, typval_T *rettv, bool is_funcref)
 
   if ((use_string && vim_strchr(s, AUTOLOAD_CHAR) == NULL) || is_funcref) {
     name = s;
-    trans_name = (char *)trans_function_name(&name, false,
-                                             TFN_INT | TFN_QUIET | TFN_NO_AUTOLOAD
-                                             | TFN_NO_DEREF, NULL, NULL);
+    trans_name = save_function_name(&name, false,
+                                    TFN_INT | TFN_QUIET | TFN_NO_AUTOLOAD | TFN_NO_DEREF, NULL);
     if (*name != NUL) {
       s = NULL;
     }
diff --git a/src/nvim/eval/userfunc.c b/src/nvim/eval/userfunc.c
index ef74ca58e3..e6b038a335 100644
--- a/src/nvim/eval/userfunc.c
+++ b/src/nvim/eval/userfunc.c
@@ -1886,6 +1886,27 @@ theend:
   return (char_u *)name;
 }
 
+/// Call trans_function_name(), except that a lambda is returned as-is.
+/// Returns the name in allocated memory.
+char *save_function_name(char **name, bool skip, int flags, funcdict_T *fudi)
+{
+  char *p = *name;
+  char *saved;
+
+  if (strncmp(p, "<lambda>", 8) == 0) {
+    p += 8;
+    (void)getdigits(&p, false, 0);
+    saved = xstrndup(*name, (size_t)(p - *name));
+    if (fudi != NULL) {
+      CLEAR_POINTER(fudi);
+    }
+  } else {
+    saved = (char *)trans_function_name(&p, skip, flags, fudi, NULL);
+  }
+  *name = p;
+  return saved;
+}
+
 #define MAX_FUNC_NESTING 50
 
 /// List functions.
@@ -2000,14 +2021,7 @@ void ex_function(exarg_T *eap)
   // s:func      script-local function name
   // g:func      global function name, same as "func"
   p = eap->arg;
-  if (strncmp(p, "<lambda>", 8) == 0) {
-    p += 8;
-    (void)getdigits(&p, false, 0);
-    name = xstrndup(eap->arg, (size_t)(p - eap->arg));
-    CLEAR_FIELD(fudi);
-  } else {
-    name = (char *)trans_function_name(&p, eap->skip, TFN_NO_AUTOLOAD, &fudi, NULL);
-  }
+  name = save_function_name(&p, eap->skip, TFN_NO_AUTOLOAD, &fudi);
   paren = (vim_strchr(p, '(') != NULL);
   if (name == NULL && (fudi.fd_dict == NULL || !paren) && !eap->skip) {
     // Return on an invalid expression in braces, unless the expression
diff --git a/src/nvim/testdir/test_expr.vim b/src/nvim/testdir/test_expr.vim
index ea874cc398..9dbc923b96 100644
--- a/src/nvim/testdir/test_expr.vim
+++ b/src/nvim/testdir/test_expr.vim
@@ -496,6 +496,13 @@ func Test_function_with_funcref()
   call assert_fails("call function('foo()')", 'E475:')
   call assert_fails("call function('foo()')", 'foo()')
   call assert_fails("function('')", 'E129:')
+
+  let Len = {s -> strlen(s)}
+  call assert_equal(6, Len('foobar'))
+  let name = string(Len)
+  " can evaluate "function('<lambda>99')"
+  call execute('let Ref = ' .. name)
+  call assert_equal(4, Ref('text'))
 endfunc
 
 func Test_funcref()