patch 8.2.3826: Vim9: using "g:Func" as funcref doesn't work in :def function

Problem:    Vim9: using "g:Func" as a funcref does not work in a :def
            function.
Solution:   Include "g:" in the function name. (closes #9336)
diff --git a/src/testdir/test_vim9_disassemble.vim b/src/testdir/test_vim9_disassemble.vim
index 4cf37b7..76fd3fa 100644
--- a/src/testdir/test_vim9_disassemble.vim
+++ b/src/testdir/test_vim9_disassemble.vim
@@ -2413,7 +2413,7 @@
   assert_match('<SNR>\d*_UseMember\_s*' ..
           'var d = {func: Legacy}\_s*' ..
           '\d PUSHS "func"\_s*' ..
-          '\d PUSHFUNC "Legacy"\_s*' ..
+          '\d PUSHFUNC "g:Legacy"\_s*' ..
           '\d NEWDICT size 1\_s*' ..
           '\d STORE $0\_s*' ..
 
diff --git a/src/testdir/test_vim9_func.vim b/src/testdir/test_vim9_func.vim
index 9dc0d73..f97f902 100644
--- a/src/testdir/test_vim9_func.vim
+++ b/src/testdir/test_vim9_func.vim
@@ -1232,11 +1232,23 @@
       g:result = getreg('"')->count(' ')
       return ''
     enddef
+    # global function works at script level
     &operatorfunc = g:CountSpaces
     new
     'a b c d e'->setline(1)
     feedkeys("g@_", 'x')
     assert_equal(4, g:result)
+
+    &operatorfunc = ''
+    g:result = 0
+    # global function works in :def function
+    def Func()
+      &operatorfunc = g:CountSpaces
+    enddef
+    Func()
+    feedkeys("g@_", 'x')
+    assert_equal(4, g:result)
+
     bwipe!
   END
   CheckScriptSuccess(lines)
diff --git a/src/version.c b/src/version.c
index d1b667a..633ebf0 100644
--- a/src/version.c
+++ b/src/version.c
@@ -750,6 +750,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    3826,
+/**/
     3825,
 /**/
     3824,
diff --git a/src/vim9compile.c b/src/vim9compile.c
index a75219e..50dc756 100644
--- a/src/vim9compile.c
+++ b/src/vim9compile.c
@@ -1281,12 +1281,26 @@
 generate_PUSHFUNC(cctx_T *cctx, char_u *name, type_T *type)
 {
     isn_T	*isn;
+    char_u	*funcname;
 
     RETURN_OK_IF_SKIP(cctx);
     if ((isn = generate_instr_type(cctx, ISN_PUSHFUNC, type)) == NULL)
 	return FAIL;
-    isn->isn_arg.string = name == NULL ? NULL : vim_strsave(name);
+    if (name == NULL)
+	funcname = NULL;
+    else if (*name == K_SPECIAL)  // script-local
+	funcname = vim_strsave(name);
+    else
+    {
+	funcname = alloc(STRLEN(name) + 3);
+	if (funcname != NULL)
+	{
+	    STRCPY(funcname, "g:");
+	    STRCPY(funcname + 2, name);
+	}
+    }
 
+    isn->isn_arg.string = funcname;
     return OK;
 }