vim-patch:7.4.741 #4121

Problem:    When using += with ":set" a trailing comma is not recognized.
            (Issue 365)
Solution:   Don't add a second comma. Add a test. (partly by Christian
            Brabandt)

a7b7b1cef9

src/nvim/option.c

@@ -1673,6 +1673,11 @@ do_set (
                          && *newval != NUL);
                 if (adding) {
                   i = (int)STRLEN(origval);
+                  // Strip a trailing comma, would get 2.
+                  if (comma && i > 1 && origval[i - 1] == ','
+                      && origval[i - 2] != '\\') {
+                    --i;
+                  }
                   memmove(newval + i + comma, newval,
                       STRLEN(newval) + 1);
                   memmove(newval, origval, (size_t)i);

src/nvim/version.c

@@ -421,7 +421,7 @@ static int included_patches[] = {
   // 744 NA
   // 743,
   // 742,
-  // 741,
+  741,
   // 740,
   739,
   // 738 NA

test/functional/legacy/set_spec.lua

@@ -0,0 +1,15 @@
+-- Tests for :set
+
+local helpers = require('test.functional.helpers')
+local clear, execute, eval, eq =
+  helpers.clear, helpers.execute, helpers.eval, helpers.eq
+
+describe(':set', function()
+  before_each(clear)
+
+  it('recognizes a trailing comma with +=', function()
+    execute('set wildignore=*.png,')
+    execute('set wildignore+=*.jpg')
+    eq('*.png,*.jpg', eval('&wildignore'))
+  end)
+end)