https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64877
Manuel López-Ibáñez <manu at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2015-01-31
CC| |paolo.carlini at oracle dot com
Version|unknown |5.0
Ever confirmed|0 |1
--- Comment #4 from Manuel López-Ibáñez <manu at gcc dot gnu.org> ---
(In reply to Tom Tromey from comment #3)
> Oops, had the wrong gcc in $PATH.
> That test case does warn:
>
> pokyo. g++ -std=c++11 -c -Wall -Waddress -O2 x.cc
> x.cc: In instantiation of ‘S<Derived>::S() [with Derived = T]’:
> x.cc:19:8: required from here
> x.cc:9:29: warning: the address of ‘void S<Derived>::Unwrap() [with Derived
> = T]’ will never be NULL [-Waddress]
> if (&S<Derived>::Unwrap != &Derived::Unwrap)
> ^
>
>
> I think I would expect a warning on the second assert, but not the first.
We hit this code in cp/typeck.c
/* We generate:
(op0.pfn == op1.pfn
&& (!op0.pfn || op0.delta == op1.delta))
The reason for the `!op0.pfn' bit is that a NULL
pointer-to-member is any member with a zero PFN; the
DELTA field is unspecified. */
e1 = cp_build_binary_op (location,
EQ_EXPR, delta0, delta1, complain);
e2 = cp_build_binary_op (location,
EQ_EXPR,
pfn0,
build_zero_cst (TREE_TYPE (pfn0)),
complain);
e1 = cp_build_binary_op (location,
TRUTH_ORIF_EXPR, e1, e2, complain);
thus, the !op0.pfn triggers the warning. It may be enough to pass tf_none
instead of complain for the two compiler-generated expressions. Alternatively,
since we know pfn0 cannot be NULL, do not generate this check. It seems quite
wasteful to go through the huge cp_build_binary_op just to build something that
will get optimized out.
Not working on this, but it seems feasible to fix. If it is a regression, you
may even convince someone to approve it for GCC 5.
