vim-patch:7.4.1051

Problem:    Segfault when unletting "count".
Solution:   Check for readonly and locked first. (Dominique Pelle)
            Add a test.

af8af8bfac

src/nvim/eval.c

@@ -2973,24 +2973,27 @@ int do_unlet(char_u *name, int forceit)
   ht = find_var_ht_dict(name, &varname, &dict);
 
   if (ht != NULL && *varname != NUL) {
-    if (ht == &globvarht) {
-      d = &globvardict;
-    } else if (current_funccal != NULL
-               && ht == &current_funccal->l_vars.dv_hashtab) {
-      d = &current_funccal->l_vars;
-    } else {
-      di = find_var_in_ht(ht, *name, (char_u *)"", false);
-      d = di->di_tv.vval.v_dict;
-    }
-
     hi = hash_find(ht, varname);
     if (!HASHITEM_EMPTY(hi)) {
       di = HI2DI(hi);
       if (var_check_fixed(di->di_flags, name, false)
-          || var_check_ro(di->di_flags, name, false)
-          || tv_check_lock(d->dv_lock, name, false)) {
+          || var_check_ro(di->di_flags, name, false)) {
         return FAIL;
       }
+
+      if (ht == &globvarht) {
+        d = &globvardict;
+      } else if (current_funccal != NULL
+                 && ht == &current_funccal->l_vars.dv_hashtab) {
+        d = &current_funccal->l_vars;
+      } else {
+        di = find_var_in_ht(ht, *name, (char_u *)"", false);
+        d = di->di_tv.vval.v_dict;
+      }
+      if (d == NULL || tv_check_lock(d->dv_lock, name, false)) {
+        return FAIL;
+      }
+
       typval_T oldtv;
       bool watched = is_watched(dict);
 

src/nvim/testdir/Makefile

@@ -39,6 +39,7 @@ NEW_TESTS = \
 	    test_menu.res \
 	    test_syntax.res \
 	    test_timers.res \
+	    test_unlet.res \
 	    test_viml.res \
 	    test_alot.res
 

src/nvim/testdir/test_unlet.vim

@@ -0,0 +1,26 @@
+" Tests for :unlet
+
+func Test_read_only()
+  try
+    " this caused a crash
+    unlet count
+  catch
+    call assert_true(v:exception =~ ':E795:')
+  endtry
+endfunc
+
+func Test_existing()
+  let does_exist = 1
+  call assert_true(exists('does_exist'))
+  unlet does_exist
+  call assert_false(exists('does_exist'))
+endfunc
+
+func Test_not_existing()
+  unlet! does_not_exist
+  try
+    unlet does_not_exist
+  catch
+    call assert_true(v:exception =~ ':E108:')
+  endtry
+endfunc

src/nvim/version.c

@@ -642,7 +642,7 @@ static int included_patches[] = {
   1054,
   1053,
   1052,
-  // 1051,
+  1051,
   1050,
   1049,
   1048,