On Thu, Dec 05, 2024 at 01:15:49PM -0500, Jason Merrill wrote: > On 12/4/24 12:27 PM, Marek Polacek wrote: > > On Tue, Dec 03, 2024 at 04:27:22PM -0500, Jason Merrill wrote: > > > 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. > > > > Ah yes. > > > > > 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. > > > > We actually can get there. But returning error_mark_node in C++26 > > causes problems: we hit: > > > > /* If we ran into a problem, make sure we complained. */ > > gcc_assert (seen_error ()); > > > > because a permerror doesn't count as an error. Either we'd have to go > > back to DK_ERROR, or leave the patch as-is. > > Hmm, I guess cp_seen_error should also consider werrorcount.
That still wouldn't work with -Wno-array-compare. Nor would adding permerrorcount. I suppose I could still add permerrorcount and do permerrorcount++;, and have cp_seen_error check permerrorcount. Does that seem acceptable? Marek
