[Bug c/114819] New: 'constructor', 'destructor' function attributes vs. function signature

[Bug c/114819] New: 'constructor', 'destructor' function attributes vs. function signature

[tschwinge at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114819

            Bug ID: 114819
           Summary: 'constructor', 'destructor' function attributes vs.
                    function signature
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Keywords: diagnostic, documentation
          Severity: minor
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: tschwinge at gcc dot gnu.org
  Target Milestone: ---

In context of PR114818 "'constructor', 'destructor' function attributes vs.
'extern'", I also found that there's no user documentation that the
constructor, destructor function signature has to match 'void FN(void)', and
GCC currently doesn't check/diagnose this.

Should we update 'gcc/doc/extend.texi' for this, and implement a diagnostic
(warning or even error, enabled by default)?

I found that we only document in 'gcc/target.def':

    /* Output a constructor for a symbol with a given priority.  */
    DEFHOOK
    (constructor,
     "If defined, a function that outputs assembler code to arrange to call\n\
    the function referenced by @var{symbol} at initialization time.\n\
    \n\
    Assume that @var{symbol} is a @code{SYMBOL_REF} for a function taking\n\
    no arguments and with no return value.  [...]

Note "a function taking no arguments and with no return value".

[Bug c/114819] 'constructor', 'destructor' function attributes vs. function signature

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114819

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Note we incorrectly also accept it on nested functions too.