[Bug c/83559] [8 regression] -Wsuggest-attribute=const conflicts with -Wattributes warning about const attribute on function returning void

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83559

Martin Sebor <msebor at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2018-01-01
     Ever confirmed|0                           |1

--- Comment #1 from Martin Sebor <msebor at gcc dot gnu.org> ---
The new -Wattributes warning is the (deliberate) result of r255469.  The only
meaningful effect a call can have to a function that's declared with the const
attribute is return a value.  Calls to such functions that ignore the returned
value are eliminated (and diagnosed with -Wunused-value).  Likewise, calls to
const functions that return void are eliminated (though without a warning,
which seems like an omission).  As a result, it makes little sense to declare a
function to be both const and return void, and -Wsuggest-attribute=const should
not be issued for const functions.