Re: C++ PATCH to fix missing warning (PR c++/70194)

[Martin Sebor <msebor@gmail.com>]

> @@ -3974,6 +3974,38 @@ build_vec_cmp (tree_code code, tree type,
>     return build3 (VEC_COND_EXPR, type, cmp, minus_one_vec, zero_vec);
>   }
>
> +/* Possibly warn about an address never being NULL.  */
> +
> +static void
> +warn_for_null_address (location_t location, tree op, tsubst_flags_t complain)
> +{
...
> +  if (TREE_CODE (cop) == ADDR_EXPR
> +      && decl_with_nonnull_addr_p (TREE_OPERAND (cop, 0))
> +      && !TREE_NO_WARNING (cop))
> +    warning_at (location, OPT_Waddress, "the address of %qD will never "
> +		"be NULL", TREE_OPERAND (cop, 0));
> +
> +  if (CONVERT_EXPR_P (op)
> +      && TREE_CODE (TREE_TYPE (TREE_OPERAND (op, 0))) == REFERENCE_TYPE)
> +    {
> +      tree inner_op = op;
> +      STRIP_NOPS (inner_op);
> +
> +      if (DECL_P (inner_op))
> +	warning_at (location, OPT_Waddress,
> +		    "the compiler can assume that the address of "
> +		    "%qD will never be NULL", inner_op);

Since I noted the subtle differences between the phrasing of
the various -Waddress warnings in the bug, I have to ask: what is
the significance of the difference between the two warnings here?

Would it not be appropriate to issue the first warning in the latter
case?  Or perhaps even use the same text as is already used elsewhere:
"the address of %qD will always evaluate as ‘true’" (since it may not
be the macro NULL that's mentioned in the expression).

Martin