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

[Jonathan Wakely]

On 06/05/20 11:01 +0100, Jonathan Wakely wrote:
>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.

Here's a correct fix for the cppcheck complaint.

Tested powerpc64le-linux, 'make check check-parallel', committed to
master.


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