Re: [PATCH 4/4] Use const for template argument.

[Jonathan Wakely <jwakely@redhat.com>]

On 04/02/20 14:55 +0100, Martin Liska wrote:
>diff --git a/libstdc++-v3/include/parallel/multiway_merge.h b/libstdc++-v3/include/parallel/multiway_merge.h
>index 983c7b2bd9a..97a9ce0feb7 100644
>--- a/libstdc++-v3/include/parallel/multiway_merge.h
>+++ b/libstdc++-v3/include/parallel/multiway_merge.h
>@@ -118,7 +118,7 @@ namespace __gnu_parallel
>        *  @return @c true if less. */
>       friend bool
>       operator<(_GuardedIterator<_RAIter, _Compare>& __bi1,
>-               _GuardedIterator<_RAIter, _Compare>& __bi2)
>+               _GuardedIterator<_RAIter, const _Compare>& __bi2)
>       {
>        if (__bi1._M_current == __bi1._M_end)       // __bi1 is sup
>          return __bi2._M_current == __bi2._M_end;  // __bi2 is not sup
>@@ -188,7 +188,7 @@ namespace __gnu_parallel
>        *  @return @c true if less. */
>       friend bool
>       operator<(_UnguardedIterator<_RAIter, _Compare>& __bi1,
>-               _UnguardedIterator<_RAIter, _Compare>& __bi2)
>+               _UnguardedIterator<_RAIter, const _Compare>& __bi2)
>       {
>        // Normal compare.
>        return (__bi1.__comp)(*__bi1, *__bi2);


This is completely bogus, please revert.

The cppcheck warning is saying that it could be:

     const _UnguardedIterator<_RAIter, _Compare>&

which is completely different from:

     _UnguardedIterator<_RAIter, const _Compare>&

Also both parameters of operator< should have been changed, not just
one, and operator<= should have the same change.

But cppcheck is completely wrong anyway. The operator* member of
_GuardedIterator and _UnguardedIterator is not const, so trying to
dereference *__b1 and *__b2 would fail.

Nack nack nack.