[Bug c++/93625] New: inline specifier in a friend function declaration

[the1987.6 at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93625

            Bug ID: 93625
           Summary: inline specifier in a friend function declaration
           Product: gcc
           Version: 9.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: the1987.6 at gmail dot com
  Target Milestone: ---

In the latest working draft N4849, 

9.2.7 The inline specifier

"If the inline specifier is used in a friend function declaration, that
declaration shall be a definition or the function shall have previously been
declared inline."

But no error has been occurred by the following code.

---------------

struct X{
     friend inline void f();
};

void f(){}

-------

The declaration of f as inline, is not a definition.
Also there is not a previous declaration as inline.

This seems like a compiler bug.

By the way, there is the rule in N1638(published April 11, 2004).