[libc++] Fix reverse_iterator when underlying is c++20 bidirectional_iterator but not Cpp17BidirectionalIterator
#112100
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…l_iterator but not c++17 BidirectionalIterator
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@llvm/pr-subscribers-libcxx Author: Hui (huixie90) ChangesPatch is 29.57 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/112100.diff 26 Files Affected:
diff --git a/libcxx/include/__iterator/reverse_iterator.h b/libcxx/include/__iterator/reverse_iterator.h
index 50c0f21eaa286b..5e88d86ad5e9b2 100644
--- a/libcxx/include/__iterator/reverse_iterator.h
+++ b/libcxx/include/__iterator/reverse_iterator.h
@@ -136,10 +136,12 @@ class _LIBCPP_TEMPLATE_VIS reverse_iterator
_LIBCPP_HIDE_FROM_ABI constexpr pointer operator->() const
requires is_pointer_v<_Iter> || requires(const _Iter __i) { __i.operator->(); }
{
+ _Iter __tmp = current;
+ --__tmp;
if constexpr (is_pointer_v<_Iter>) {
- return std::prev(current);
+ return __tmp;
} else {
- return std::prev(current).operator->();
+ return __tmp.operator->();
}
}
#else
diff --git a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.cmp/equal.pass.cpp b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.cmp/equal.pass.cpp
index fcf8d88fcf62be..b5cb1324a59248 100644
--- a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.cmp/equal.pass.cpp
+++ b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.cmp/equal.pass.cpp
@@ -33,6 +33,10 @@ TEST_CONSTEXPR_CXX17 bool tests() {
test(bidirectional_iterator<const char*>(s), bidirectional_iterator<const char*>(s+1), false);
test(random_access_iterator<const char*>(s), random_access_iterator<const char*>(s), true);
test(random_access_iterator<const char*>(s), random_access_iterator<const char*>(s+1), false);
+#if TEST_STD_VER >= 20
+ test(cpp20_random_access_iterator<const char*>(s), cpp20_random_access_iterator<const char*>(s), true);
+ test(cpp20_random_access_iterator<const char*>(s), cpp20_random_access_iterator<const char*>(s+1), false);
+#endif
test(s, s, true);
test(s, s+1, false);
return true;
diff --git a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.cmp/greater-equal.pass.cpp b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.cmp/greater-equal.pass.cpp
index fdcd02abb0d8ed..3c37dce13dc6af 100644
--- a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.cmp/greater-equal.pass.cpp
+++ b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.cmp/greater-equal.pass.cpp
@@ -32,6 +32,11 @@ TEST_CONSTEXPR_CXX17 bool tests() {
test(random_access_iterator<const char*>(s), random_access_iterator<const char*>(s), true);
test(random_access_iterator<const char*>(s), random_access_iterator<const char*>(s+1), true);
test(random_access_iterator<const char*>(s+1), random_access_iterator<const char*>(s), false);
+#if TEST_STD_VER >= 20
+ test(cpp20_random_access_iterator<const char*>(s), cpp20_random_access_iterator<const char*>(s), true);
+ test(cpp20_random_access_iterator<const char*>(s), cpp20_random_access_iterator<const char*>(s+1), true);
+ test(cpp20_random_access_iterator<const char*>(s+1), cpp20_random_access_iterator<const char*>(s), false);
+#endif
test(s, s, true);
test(s, s+1, true);
test(s+1, s, false);
diff --git a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.cmp/greater.pass.cpp b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.cmp/greater.pass.cpp
index dce331e519646f..288691b7147757 100644
--- a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.cmp/greater.pass.cpp
+++ b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.cmp/greater.pass.cpp
@@ -32,6 +32,11 @@ TEST_CONSTEXPR_CXX17 bool tests() {
test(random_access_iterator<const char*>(s), random_access_iterator<const char*>(s), false);
test(random_access_iterator<const char*>(s), random_access_iterator<const char*>(s+1), true);
test(random_access_iterator<const char*>(s+1), random_access_iterator<const char*>(s), false);
+#if TEST_STD_VER >= 20
+ test(cpp20_random_access_iterator<const char*>(s), cpp20_random_access_iterator<const char*>(s), false);
+ test(cpp20_random_access_iterator<const char*>(s), cpp20_random_access_iterator<const char*>(s+1), true);
+ test(cpp20_random_access_iterator<const char*>(s+1), cpp20_random_access_iterator<const char*>(s), false);
+#endif
test(s, s, false);
test(s, s+1, true);
test(s+1, s, false);
diff --git a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.cmp/less-equal.pass.cpp b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.cmp/less-equal.pass.cpp
index e9cea6250a7645..f7babf1ff48d20 100644
--- a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.cmp/less-equal.pass.cpp
+++ b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.cmp/less-equal.pass.cpp
@@ -32,6 +32,11 @@ TEST_CONSTEXPR_CXX17 bool tests() {
test(random_access_iterator<const char*>(s), random_access_iterator<const char*>(s), true);
test(random_access_iterator<const char*>(s), random_access_iterator<const char*>(s+1), false);
test(random_access_iterator<const char*>(s+1), random_access_iterator<const char*>(s), true);
+#if TEST_STD_VER >= 20
+ test(cpp20_random_access_iterator<const char*>(s), cpp20_random_access_iterator<const char*>(s), true);
+ test(cpp20_random_access_iterator<const char*>(s), cpp20_random_access_iterator<const char*>(s+1), false);
+ test(cpp20_random_access_iterator<const char*>(s+1), cpp20_random_access_iterator<const char*>(s), true);
+#endif
test(s, s, true);
test(s, s+1, false);
test(s+1, s, true);
diff --git a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.cmp/less.pass.cpp b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.cmp/less.pass.cpp
index b66147cf3a03c3..6f3d82c23430fb 100644
--- a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.cmp/less.pass.cpp
+++ b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.cmp/less.pass.cpp
@@ -32,6 +32,11 @@ TEST_CONSTEXPR_CXX17 bool tests() {
test(random_access_iterator<const char*>(s), random_access_iterator<const char*>(s), false);
test(random_access_iterator<const char*>(s), random_access_iterator<const char*>(s+1), false);
test(random_access_iterator<const char*>(s+1), random_access_iterator<const char*>(s), true);
+#if TEST_STD_VER >= 20
+ test(cpp20_random_access_iterator<const char*>(s), cpp20_random_access_iterator<const char*>(s), false);
+ test(cpp20_random_access_iterator<const char*>(s), cpp20_random_access_iterator<const char*>(s+1), false);
+ test(cpp20_random_access_iterator<const char*>(s+1), cpp20_random_access_iterator<const char*>(s), true);
+#endif
test(s, s, false);
test(s, s+1, false);
test(s+1, s, true);
diff --git a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.cmp/not-equal.pass.cpp b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.cmp/not-equal.pass.cpp
index 37a6ff1302ce77..1b921ace4a67f0 100644
--- a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.cmp/not-equal.pass.cpp
+++ b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.cmp/not-equal.pass.cpp
@@ -33,6 +33,10 @@ TEST_CONSTEXPR_CXX17 bool tests() {
test(bidirectional_iterator<const char*>(s), bidirectional_iterator<const char*>(s+1), true);
test(random_access_iterator<const char*>(s), random_access_iterator<const char*>(s), false);
test(random_access_iterator<const char*>(s), random_access_iterator<const char*>(s+1), true);
+#if TEST_STD_VER >= 20
+ test(cpp20_random_access_iterator<const char*>(s), cpp20_random_access_iterator<const char*>(s), false);
+ test(cpp20_random_access_iterator<const char*>(s), cpp20_random_access_iterator<const char*>(s+1), true);
+#endif
test(s, s, false);
test(s, s+1, true);
return true;
diff --git a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.cons/assign.pass.cpp b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.cons/assign.pass.cpp
index 0e5123a49e2b56..f9d2efa7c2a8cc 100644
--- a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.cons/assign.pass.cpp
+++ b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.cons/assign.pass.cpp
@@ -59,6 +59,9 @@ TEST_CONSTEXPR_CXX17 bool tests() {
Derived d;
test<bidirectional_iterator<Base*> >(bidirectional_iterator<Derived*>(&d));
test<random_access_iterator<const Base*> >(random_access_iterator<Derived*>(&d));
+#if TEST_STD_VER >= 20
+ test<cpp20_random_access_iterator<const Base*> >(cpp20_random_access_iterator<Derived*>(&d));
+#endif
test<Base*>(&d);
char c = '\0';
diff --git a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.cons/ctor.default.pass.cpp b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.cons/ctor.default.pass.cpp
index fcb96de91d1a02..90047b19f5a63a 100644
--- a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.cons/ctor.default.pass.cpp
+++ b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.cons/ctor.default.pass.cpp
@@ -26,6 +26,9 @@ TEST_CONSTEXPR_CXX17 void test() {
TEST_CONSTEXPR_CXX17 bool tests() {
test<bidirectional_iterator<const char*> >();
test<random_access_iterator<char*> >();
+#if TEST_STD_VER >= 20
+ test<cpp20_random_access_iterator<char*> >();
+#endif
test<char*>();
test<const char*>();
return true;
diff --git a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.cons/ctor.iter.pass.cpp b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.cons/ctor.iter.pass.cpp
index 801b2cf879ce5b..72e77b08564219 100644
--- a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.cons/ctor.iter.pass.cpp
+++ b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.cons/ctor.iter.pass.cpp
@@ -28,6 +28,9 @@ TEST_CONSTEXPR_CXX17 bool tests() {
const char s[] = "123";
test(bidirectional_iterator<const char*>(s));
test(random_access_iterator<const char*>(s));
+#if TEST_STD_VER >= 20
+ test(cpp20_random_access_iterator<const char*>(s));
+#endif
test(s);
return true;
}
diff --git a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.cons/ctor.reverse_iterator.pass.cpp b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.cons/ctor.reverse_iterator.pass.cpp
index 8f315e83f6d7b4..fa967b45b1d9f8 100644
--- a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.cons/ctor.reverse_iterator.pass.cpp
+++ b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.cons/ctor.reverse_iterator.pass.cpp
@@ -33,6 +33,9 @@ TEST_CONSTEXPR_CXX17 bool tests() {
Derived d;
test<bidirectional_iterator<Base*> >(bidirectional_iterator<Derived*>(&d));
test<random_access_iterator<const Base*> >(random_access_iterator<Derived*>(&d));
+#if TEST_STD_VER >= 20
+ test<cpp20_random_access_iterator<const Base*> >(cpp20_random_access_iterator<Derived*>(&d));
+#endif
test<Base*>(&d);
return true;
}
diff --git a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.conv/base.pass.cpp b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.conv/base.pass.cpp
index 4fb33f54260457..ded372a32b0b3a 100644
--- a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.conv/base.pass.cpp
+++ b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.conv/base.pass.cpp
@@ -18,20 +18,28 @@
#include "test_macros.h"
#include "test_iterators.h"
-TEST_CONSTEXPR_CXX17 bool test() {
- typedef bidirectional_iterator<int*> Iter;
+template <class Iter>
+TEST_CONSTEXPR_CXX17 void test() {
int i = 0;
Iter iter(&i);
std::reverse_iterator<Iter> const reverse(iter);
- std::reverse_iterator<Iter>::iterator_type base = reverse.base();
+ typename std::reverse_iterator<Iter>::iterator_type base = reverse.base();
assert(base == Iter(&i));
+}
+
+TEST_CONSTEXPR_CXX17 bool tests() {
+ test<bidirectional_iterator<int*> >();
+ test<random_access_iterator<int*> >();
+#if TEST_STD_VER >= 20
+ test<cpp20_random_access_iterator<int*>>();
+#endif
return true;
}
int main(int, char**) {
- test();
+ tests();
#if TEST_STD_VER > 14
- static_assert(test(), "");
+ static_assert(tests(), "");
#endif
return 0;
}
diff --git a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.elem/arrow.pass.cpp b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.elem/arrow.pass.cpp
index 15d18d9145ef0c..ac862ef1a2492c 100644
--- a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.elem/arrow.pass.cpp
+++ b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.elem/arrow.pass.cpp
@@ -24,6 +24,54 @@
#include "test_macros.h"
+#if TEST_STD_VER >= 20
+template <class It>
+class cpp20_bidirectional_iterator_with_arrow {
+ It it_;
+
+public:
+ using iterator_category = std::input_iterator_tag;
+ using iterator_concept = std::bidirectional_iterator_tag;
+ using value_type = std::iterator_traits<It>::value_type;
+ using difference_type = std::iterator_traits<It>::difference_type;
+
+ cpp20_bidirectional_iterator_with_arrow() : it_() {}
+ explicit cpp20_bidirectional_iterator_with_arrow(It it) : it_(it) {}
+
+ decltype(auto) operator*() const { return *it_; }
+
+ auto operator->() const {
+ if constexpr (std::is_pointer_v<It>) {
+ return it_;
+ } else {
+ return it_.operator->();
+ }
+ }
+
+ cpp20_bidirectional_iterator_with_arrow& operator++() {
+ ++it_;
+ return *this;
+ }
+ cpp20_bidirectional_iterator_with_arrow& operator--() {
+ --it_;
+ return *this;
+ }
+ cpp20_bidirectional_iterator_with_arrow operator++(int) { return cpp20_bidirectional_iterator_with_arrow(it_++); }
+ cpp20_bidirectional_iterator_with_arrow operator--(int) { return cpp20_bidirectional_iterator_with_arrow(it_--); }
+
+ friend bool
+ operator==(const cpp20_bidirectional_iterator_with_arrow& x, const cpp20_bidirectional_iterator_with_arrow& y) {
+ return x.it_ == y.it_;
+ }
+ friend bool
+ operator!=(const cpp20_bidirectional_iterator_with_arrow& x, const cpp20_bidirectional_iterator_with_arrow& y) {
+ return x.it_ != y.it_;
+ }
+
+ friend It base(const cpp20_bidirectional_iterator_with_arrow& i) { return i.it_; }
+};
+#endif
+
class A
{
int data_;
@@ -113,6 +161,16 @@ int main(int, char**)
static_assert(it1->get() == gC.get(), "");
}
+#endif
+#if TEST_STD_VER >= 20
+ {
+ // The underlying iterator models c++20 bidirectional_iterator,
+ // but does not satisfy c++17 BidirectionalIterator named requirement
+ B data[] = {1, 2, 3};
+ cpp20_bidirectional_iterator_with_arrow<B*> iter(data + 3);
+ auto ri = std::make_reverse_iterator(iter);
+ assert(ri->get() == 3);
+ }
#endif
{
((void)gC);
diff --git a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.elem/bracket.pass.cpp b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.elem/bracket.pass.cpp
index 37a857ceefa83d..59bea3a6235ba4 100644
--- a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.elem/bracket.pass.cpp
+++ b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.elem/bracket.pass.cpp
@@ -33,6 +33,10 @@ TEST_CONSTEXPR_CXX17 bool tests() {
const char* s = "1234567890";
test(random_access_iterator<const char*>(s+5), 4, '1');
test(random_access_iterator<const char*>(s+5), 0, '5');
+#if TEST_STD_VER >= 20
+ test(cpp20_random_access_iterator<const char*>(s+5), 4, '1');
+ test(cpp20_random_access_iterator<const char*>(s+5), 0, '5');
+#endif
test(s+5, 4, '1');
test(s+5, 0, '5');
return true;
diff --git a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.elem/dereference.pass.cpp b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.elem/dereference.pass.cpp
index 292c6da9a7733e..f568a918a6a835 100644
--- a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.elem/dereference.pass.cpp
+++ b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.elem/dereference.pass.cpp
@@ -21,6 +21,7 @@
#include <cassert>
#include "test_macros.h"
+#include "test_iterators.h"
class A
{
@@ -47,6 +48,10 @@ int main(int, char**)
{
A a;
test(&a+1, A());
+ test(random_access_iterator<A*>(&a+1), A());
+#if TEST_STD_VER >= 20
+ test(cpp20_random_access_iterator<A*>(&a+1), A());
+#endif
#if TEST_STD_VER > 14
{
diff --git a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.nav/decrement-assign.pass.cpp b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.nav/decrement-assign.pass.cpp
index 8c83ec1e9389f9..dd5fd2c88645ad 100644
--- a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.nav/decrement-assign.pass.cpp
+++ b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.nav/decrement-assign.pass.cpp
@@ -30,6 +30,9 @@ TEST_CONSTEXPR_CXX17 void test(It i, typename std::iterator_traits<It>::differen
TEST_CONSTEXPR_CXX17 bool tests() {
const char* s = "1234567890";
test(random_access_iterator<const char*>(s+5), 5, random_access_iterator<const char*>(s+10));
+#if TEST_STD_VER >= 20
+ test(cpp20_random_access_iterator<const char*>(s+5), 5, cpp20_random_access_iterator<const char*>(s+10));
+#endif
test(s+5, 5, s+10);
return true;
}
diff --git a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.nav/increment-assign.pass.cpp b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.nav/increment-assign.pass.cpp
index e32fac9fc24fe1..74ab3f96189233 100644
--- a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.nav/increment-assign.pass.cpp
+++ b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.nav/increment-assign.pass.cpp
@@ -30,6 +30,9 @@ TEST_CONSTEXPR_CXX17 void test(It i, typename std::iterator_traits<It>::differen
TEST_CONSTEXPR_CXX17 bool tests() {
char const* s = "1234567890";
test(random_access_iterator<const char*>(s+5), 5, random_access_iterator<const char*>(s));
+#if TEST_STD_VER >= 20
+ test(cpp20_random_access_iterator<const char*>(s+5), 5, cpp20_random_access_iterator<const char*>(s));
+#endif
test(s+5, 5, s);
return true;
}
diff --git a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.nav/minus.pass.cpp b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.nav/minus.pass.cpp
index f2474dd7669f2c..816c11c65d2c48 100644
--- a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.nav/minus.pass.cpp
+++ b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.nav/minus.pass.cpp
@@ -29,6 +29,9 @@ TEST_CONSTEXPR_CXX17 void test(It i, typename std::iterator_traits<It>::differen
TEST_CONSTEXPR_CXX17 bool tests() {
const char* s = "1234567890";
test(random_access_iterator<const char*>(s+5), 5, random_access_iterator<const char*>(s+10));
+#if TEST_STD_VER >= 20
+ test(cpp20_random_access_iterator<const char*>(s+5), 5, cpp20_random_access_iterator<const char*>(s+10));
+#endif
test(s+5, 5, s+10);
return true;
}
diff --git a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.nav/plus.pass.cpp b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.nav/plus.pass.cpp
index 5673425e796757..72640cd0ec80c3 100644
--- a/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.nav/plus.pass.cpp
+++ b/libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.nav/plus.pass.cpp
@@ -29,6 +29,9 @@ TEST_CONSTEXPR_CXX17 void test(It i, typename std::iterator_traits<It>::differen
TEST_CONSTEXPR_CXX17 bool tests() {
const char* s = "1234567890";
test(random_access_iterator<const char*>(s+5), 5, random_access_iterator<const char*>(s));
+#if TEST_STD_VER >= 20
+ ...
[truncated]
|
|
✅ With the latest revision this PR passed the C/C++ code formatter. |
huixie90
changed the title
reverse_iterator when underlying is c++20 bidirectional_iterator but not c++17 BidirectionalIteratorreverse_iterator when underlying is c++20 bidirectional_iterator but not Cpp17BidirectionalIterator
huixie90
changed the title
reverse_iterator when underlying is c++20 bidirectional_iterator but not Cpp17BidirectionalIteratorreverse_iterator when underlying is c++20 bidirectional_iterator but not Cpp17BidirectionalIterator
frederick-vs-ja
approved these changes
Oct 13, 2024
ldionne
approved these changes
Oct 15, 2024
libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.elem/arrow.pass.cpp
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…everse.iter.elem/arrow.pass.cpp Co-authored-by: Louis Dionne <[email protected]>
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Oct 22, 2024
…al_iterator` but not `Cpp17BidirectionalIterator` (llvm#112100) `reverse_iterator` supports either c++20 `bidirectional_iterator` or `Cpp17BidirectionalIterator ` http://eel.is/c++draft/reverse.iter.requirements The current `reverse_iterator` uses `std::prev` in its `operator->`, which only supports the `Cpp17BidirectionalIterator` properly. If the underlying iterator is c++20 `bidirectional_iterator` but does not satisfy the named requirement `Cpp17BidirectionalIterator`, (examples are `zip_view::iterator`, `flat_map::iterator`), the current `std::prev` silently compiles but does a no-op and returns the same iterator back. So `reverse_iterator::operator->` will silently give a wrong answer. Even if we fix the behaviour of `std::prev`, at best, we could fail to compile the code. But this is not ok, because we need to support this kind of iterators in `reverse_iterator`. The solution is simply to not use `std::prev`. --------- Co-authored-by: Louis Dionne <[email protected]>
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reverse_iteratorsupports either c++20bidirectional_iteratororCpp17BidirectionalIteratorhttp://eel.is/c++draft/reverse.iter.requirements
The current
reverse_iteratorusesstd::previn itsoperator->, which only supports theCpp17BidirectionalIteratorproperly.If the underlying iterator is c++20
bidirectional_iteratorbut does not satisfy the named requirementCpp17BidirectionalIterator, (examples arezip_view::iterator,flat_map::iterator), the currentstd::prevsilently compiles but does a no-op and returns the same iterator back. Soreverse_iterator::operator->will silently give a wrong answer.Even if we fix the behaviour of
std::prev, at best, we could fail to compile the code. But this is not ok, because we need to support this kind of iterators inreverse_iterator.The solution is simply to not use
std::prev.