https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99032
Bug ID: 99032
Summary: GCC accepts attributes on friend declarations (not
definitions)
Product: gcc
Version: 10.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: dangelog at gmail dot com
Target Milestone: ---
Hi,
The following code is accepted by GCC 10.2:
struct S { [[deprecated]] friend void f(); };
No errors and no warnings are generated under -Wall -Wextra -pedantic.
The code is however ill-formed: an attribute cannot appear on a friend
declaration which isn't also a definition:
https://eel.is/c++draft/dcl.attr#grammar-5.sentence-3
If an attribute-specifier-seq appertains to a friend declaration
([class.friend]), that declaration shall be a definition.
For comparison, Clang rejects this, and MSVC accepts it (without warnings).
