[libc++][test] Fix overload_compare_iterator::iterator_category
#112165
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`overload_compare_iterator` only supports operations required for forward iterators. On the other hand, it is used for output iterators of uninitialized memory algorithms, which requires it to be forward iterator. As a result, `overload_compare_iterator<I>::iterator_category` should always be `std::forward_iterator_tag` if we don't extends its ability. The correct `iterator_category` can prevent standard library implementations like MSVC STL to attempt random access operations on it.
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@llvm/pr-subscribers-libcxx Author: A. Jiang (frederick-vs-ja) Changes
As a result, Fixes #74756. Full diff: https://github.com/llvm/llvm-project/pull/112165.diff 1 Files Affected:
diff --git a/libcxx/test/std/utilities/memory/specialized.algorithms/overload_compare_iterator.h b/libcxx/test/std/utilities/memory/specialized.algorithms/overload_compare_iterator.h
index d5dcb08c37ed6f..f3b37292e717a1 100644
--- a/libcxx/test/std/utilities/memory/specialized.algorithms/overload_compare_iterator.h
+++ b/libcxx/test/std/utilities/memory/specialized.algorithms/overload_compare_iterator.h
@@ -12,6 +12,7 @@
#include <iterator>
#include <memory>
+#include <type_traits>
#include "test_macros.h"
@@ -21,11 +22,15 @@
// See https://github.com/llvm/llvm-project/issues/69334 for details.
template <class Iterator>
struct overload_compare_iterator {
+ static_assert(
+ std::is_base_of<std::forward_iterator_tag, typename std::iterator_traits<Iterator>::iterator_category>::value,
+ "overload_compare_iterator can only adapt forward iterators");
+
using value_type = typename std::iterator_traits<Iterator>::value_type;
using difference_type = typename std::iterator_traits<Iterator>::difference_type;
using reference = typename std::iterator_traits<Iterator>::reference;
using pointer = typename std::iterator_traits<Iterator>::pointer;
- using iterator_category = typename std::iterator_traits<Iterator>::iterator_category;
+ using iterator_category = std::forward_iterator_tag;
overload_compare_iterator() = default;
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philnik777
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Oct 14, 2024
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philnik777
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This shouldn't be marked [NFC], since it fixes a bug in the test suite. Other than that LGTM.
frederick-vs-ja
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overload_compare_iterator::iterator_categoryoverload_compare_iterator::iterator_category
ldionne
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Oct 15, 2024
DanielCChen
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Oct 16, 2024
…vm#112165) `overload_compare_iterator` only supports operations required for forward iterators. On the other hand, it is used for output iterators of uninitialized memory algorithms, which requires it to be forward iterator. As a result, `overload_compare_iterator<I>::iterator_category` should always be `std::forward_iterator_tag` if we don't extend its ability. The correct `iterator_category` can prevent standard library implementations like MSVC STL attempting random access operations on `overload_compare_iterator`. Fixes llvm#74756.
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overload_compare_iteratoronly supports operations required for forward iterators. On the other hand, it is used for output iterators of uninitialized memory algorithms, which requires it to be forward iterator.As a result,
overload_compare_iterator<I>::iterator_categoryshould always bestd::forward_iterator_tagif we don't extend its ability. The correctiterator_categorycan prevent standard library implementations like MSVC STL attempting random access operations onoverload_compare_iterator.Fixes #74756.