Fwd: [PATCH] Attribute for unused warning for variables of non-trivial types

[Jason Merrill]

On 06/30/2013 04:21 AM, Lubos Lunak wrote:
> Are you sure this should be covered by -Wunused-but-set-variable rather than
> plain -Wunused-variable? While strictly technically speaking the variable is
> set by the ctor, it's conceptually confusing (is "string s;" really set from
> the developer's point of view?), and it's inconsistent with basic types:
>
> $ echo "void f() { int a = 1; } " | g++ -x c++ -fsyntax-only -Wall -
> <stdin>: In function ‘void f()’:
> <stdin>:1:16: warning: unused variable ‘a’ [-Wunused-variable]

Ah, I didn't realize that we warn about unused variables with 
initializers. OK, then.

> +  { "warn_unused",            0, 0, false, false, false,
> +                             handle_warn_unused_attribute, false },

Was it a deliberate decision to put this in the c-common attributes 
rather than the C++-specific ones?  I'm not saying it's wrong, just 
interested in your thinking.

> +               || lookup_attribute ("warn_unused", TYPE_ATTRIBUTES (TREE_TYPE (decl)))))

Line longer than 80 characters.

> +      if( !lookup_attribute ("warn_unused", TYPE_ATTRIBUTES (type)))

Space before paren, not after.

And your patch is missing a ChangeLog entry.

It looks like you don't have a copyright assignment on file with the 
FSF; this patch is small enough not to need one, but we should take care 
of that so that future patches don't get blocked.

Jason