runtime(vim): Update base-syntax, match Vim9 bool/null literal args to :if/:while/:return
Match Vim9 boolean and null literals in expression arguments of :if,
:elseif, :while and :return.
closes: #15684
Signed-off-by: Doug Kearns <dougkearns@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/syntax/testdir/input/vim9_expr.vim b/runtime/syntax/testdir/input/vim9_expr.vim
new file mode 100644
index 0000000..784d861
--- /dev/null
+++ b/runtime/syntax/testdir/input/vim9_expr.vim
@@ -0,0 +1,20 @@
+vim9script
+# Vim9-script expressions
+
+
+# Command {expr} arguments
+
+if true
+ echo true
+elseif false
+ echo false
+endif
+
+while true
+ break
+endwhile
+
+def Foo(): bool
+ return true
+enddef
+