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author | Jonathan Wakely <jwakely@redhat.com> | 2022-08-24 13:53:27 +0100 |
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committer | Jonathan Wakely <jwakely@redhat.com> | 2022-08-24 15:22:44 +0100 |
commit | 530f80451a9e76896a0294e0f4bd59baff1ac27f (patch) | |
tree | e8fea123ff26374a51fa5ed4a907f16072df79d9 /libstdc++-v3/testsuite/25_algorithms | |
parent | 0b7c9254998b3fb2c39f6b86b5b196f415530205 (diff) | |
download | gcc-530f80451a9e76896a0294e0f4bd59baff1ac27f.tar.gz |
libstdc++: Fix regression in std::stable_sort
The recent change to split out the cold path of std::stable_sort caused
a regression for some Qt code. The problem is that the library now adds
a value of type ptrdiff_t to the iterator, which is ambiguous with
-pedantic. The addition could either convert the iterator to a built-in
pointer and add the ptrdiff_t to that, or it could convert the ptrdiff_t
to the iterator's difference_type and use the iterator's own operator+.
The fix is to cast the ptrdiff_t value to the difference type first.
libstdc++-v3/ChangeLog:
* include/bits/stl_algo.h (__stable_sort): Cast size to
iterator's difference type.
* testsuite/25_algorithms/stable_sort/4.cc: New test.
Diffstat (limited to 'libstdc++-v3/testsuite/25_algorithms')
-rw-r--r-- | libstdc++-v3/testsuite/25_algorithms/stable_sort/4.cc | 51 |
1 files changed, 51 insertions, 0 deletions
diff --git a/libstdc++-v3/testsuite/25_algorithms/stable_sort/4.cc b/libstdc++-v3/testsuite/25_algorithms/stable_sort/4.cc new file mode 100644 index 00000000000..b7bda4eeaca --- /dev/null +++ b/libstdc++-v3/testsuite/25_algorithms/stable_sort/4.cc @@ -0,0 +1,51 @@ +// { dg-options "-pedantic" } +// { dg-do compile } + +#include <algorithm> + +/* This type is reduced from QTypedArrayData::iterator which has an implicit + * conversion to its pointer type and a difference type of int. + * The expression Iter() + ptrdiff_t(0) is ambiguous with -pedantic because it + * could either convert the RHS to int and use Iter::operator+(int) + * or it could convert the LHS to pointer and use built-in pointer arithmetic. + */ +struct Iter +{ + struct value_type { bool operator<(value_type) const; }; + typedef value_type* pointer; + typedef value_type& reference; + typedef std::random_access_iterator_tag iterator_category; + typedef int difference_type; + + reference operator*() const; + pointer operator->() const; + + reference operator[](difference_type) const; + + Iter& operator++(); + Iter& operator--(); + Iter operator++(int); + Iter operator--(int); + + Iter& operator+=(difference_type); + Iter& operator-=(difference_type); + + Iter operator+(difference_type) const; + Iter operator-(difference_type) const; + + difference_type operator-(Iter) const; + + operator pointer() const; // XXX this causes the ambiguity + + bool operator==(Iter) const; + bool operator!=(Iter) const; + + bool operator<(Iter) const; +}; + +Iter operator+(Iter::difference_type, Iter); + +int main() +{ + std::stable_sort(Iter(), Iter()); +} |