[Bug c++/92521] New: [[deprecated(("string-literal"))]] accepted with extra parentheses

[jsm28 at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92521

            Bug ID: 92521
           Summary: [[deprecated(("string-literal"))]] accepted with extra
                    parentheses
           Product: gcc
           Version: 10.0
            Status: UNCONFIRMED
          Keywords: accepts-invalid
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jsm28 at gcc dot gnu.org
  Target Milestone: ---

The C++ standard says the only valid attribute-argument-clause for the
"deprecated" attribute is (string-literal). In particular, redundantly
parenthesized string literals are not permitted. However, the C++ front end
accepts invalid code such as:

int a [[deprecated((((""))))]];