[Bug c++/90797] New: gcc reject valid code

[zhonghao at pku dot org.cn]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90797

            Bug ID: 90797
           Summary: gcc reject valid code
           Product: gcc
           Version: 10.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: zhonghao at pku dot org.cn
  Target Milestone: ---

My gcc is 10.0.0, and my code is:

class a {
 public:
 int b(int a());
};
int x();
void y() {
 a z; z.b(x);
}

The error message is:

<source>:3:8: error: return type specification for constructor invalid

    3 |  int b(int a());

      |        ^~~

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

<source>:7:11: error: invalid conversion from 'int (*)()' to 'void (*)()'
[-fpermissive]

    7 |  a z; z.b(x);

      |           ^

      |           |

      |           int (*)()

<source>:3:12: note:   initializing argument 1 of 'int a::b(void (*)())'

    3 |  int b(int a());

      |        ~~~~^~~

Compiler returned: 1

clang, icc, and msvc all accept the code.