This resolves the following clang++ error message:
../../gdb/symtab.c:4892:33: error: logical not is only applied to the left hand side of this comparison [-Werror,-Wlogical-not-parentheses]
if (preg.has_value () && !preg->exec (sym->natural_name (), 0,
^
../../gdb/symtab.c:4892:33: note: add parentheses after the '!' to evaluate the comparison first
if (preg.has_value () && !preg->exec (sym->natural_name (), 0,
^
(
../../gdb/symtab.c:4892:33: note: add parentheses around left hand side expression to silence this warning
if (preg.has_value () && !preg->exec (sym->natural_name (), 0,
^
(