[Bug c++/92402] New: parsing error in lambda trail return type with decltype, statement expressions and structure bindings

[jonas.simple at googlemail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92402

            Bug ID: 92402
           Summary: parsing error in lambda trail return type with
                    decltype, statement expressions and structure bindings
           Product: gcc
           Version: 9.2.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jonas.simple at googlemail dot com
  Target Milestone: ---

The following code:

int a[1];

void  f() {
    decltype(({auto&& [x] = a; 0;})) b;
    (void)[]() -> decltype(({auto&& [x] = a; 0;})) { return 0; };
}

when compiled with gcc 9.2 and --std=c++17

outputs:

<source>: In function 'void f()':

<source>:5:39: internal compiler error: in cp_parser_decomposition_declaration,
at cp/parser.c:13786

    5 |     (void)[]() -> decltype(({auto&& [x] = a; 0;})) { return 0; };
      |                                       ^

Please submit a full bug report, with preprocessed source if appropriate.