On 12/3/24 2:46 PM, Marek Polacek wrote:
On Thu, Nov 28, 2024 at 12:04:56PM -0500, Jason Merrill wrote:
On 11/27/24 9:06 PM, Marek Polacek wrote:
Not a bugfix, but this should only affect C++26.
Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
-- >8--
This patch implements P2865R5 by promoting the warning to error in C++26
only. -Wno-array-compare shouldn't disable the error, so adjust the call
sites as well.
I think it's fine for -Wno-array-compare to suppress the error (and
-Wno-error=array-compare to reduce it to a warning), so how about
DK_PERMERROR rather than DK_ERROR?
Sounds good.
We also need SFINAE for this when !tf_warning_or_error.
I've added Warray-compare-1.C, which has:
template<int I>
void f (int(*)[arr1 == arr2 ? I : I]);
but when we call cp_build_binary_op from the parser, complain is
tf_warning_or_error, so we warn (as does clang++). I suspect
that goes against [temp.deduct.general]/8.
No, that's fine; in C++26 that template is IFNDR because no well-formed
instantiation exists, it's OK for us to give a diagnostic and then
continue just like in a non-template.
I'm not sure there is a SFINAE situation where this would come up, but
I'd still like to adjust this:
@@ -6125,11 +6124,10 @@ cp_build_binary_op (const op_location_t &location,
"comparison with string literal results "
"in unspecified behavior");
}
- else if (warn_array_compare
- && TREE_CODE (TREE_TYPE (orig_op0)) == ARRAY_TYPE
+ else if (TREE_CODE (TREE_TYPE (orig_op0)) == ARRAY_TYPE
&& TREE_CODE (TREE_TYPE (orig_op1)) == ARRAY_TYPE
&& code != SPACESHIP_EXPR
- && (complain & tf_warning))
+ && (complain & tf_warning_or_error))
do_warn_array_compare (location, code,
tree_strip_any_location_wrapper (orig_op0),
tree_strip_any_location_wrapper (orig_op1));
If we happen to get here when not complaining, we'll silently accept it.
Either we should handle that case by returning error_mark_node in
C++26 and above, or we should assert that it can't happen.
Jason
