My recent r15-9381-g648d5c26e25497 change assumes that a contiguous
iterator with the correct value_type can be converted to a const charT*
but that's not true for volatile charT*. The optimization should only be
done if it can be converted to the right pointer type.
Additionally, the generic loop for non-contiguous iterators needs an
explicit cast to deal with iterators that have a reference type that is
not explicitly convertible to charT.
libstdc++-v3/ChangeLog:
PR libstdc++/119748
* include/bits/basic_string.h (_S_copy_chars): Only optimize for
contiguous iterators that are convertible to const charT*. Use
explicit conversion to charT after dereferencing iterator.
(_S_copy_range): Likewise for contiguous ranges.
* include/bits/cow_string.h (_S_copy_chars): Likewise.
(basic_string(from_range_t, R&&, const Alloc&)): Likewise.
* testsuite/21_strings/basic_string/cons/char/119748.cc: New
test.
* testsuite/21_strings/basic_string/cons/wchar_t/119748.cc:
New test.
---
Tested x86_64-linux.
The static_cast<_CharT>(*__k1) bit in _S_copy_chars is relevant for the
branches too. Thinking about it now, I should probably add another
test with iterators that have a value_type with 'explicit operator char()'
because volatile char* isn't the only case that fails.
libstdc++-v3/include/bits/basic_string.h | 24 +++++++++++++------
libstdc++-v3/include/bits/cow_string.h | 17 +++++++++----
.../basic_string/cons/char/119748.cc | 11 +++++++++
.../basic_string/cons/wchar_t/119748.cc | 11 +++++++++
4 files changed, 51 insertions(+), 12 deletions(-)
create mode 100644
libstdc++-v3/testsuite/21_strings/basic_string/cons/char/119748.cc
create mode 100644
libstdc++-v3/testsuite/21_strings/basic_string/cons/wchar_t/119748.cc
diff --git a/libstdc++-v3/include/bits/basic_string.h
b/libstdc++-v3/include/bits/basic_string.h
index 9c431c765ab..c90bd099b63 100644
--- a/libstdc++-v3/include/bits/basic_string.h
+++ b/libstdc++-v3/include/bits/basic_string.h
@@ -488,8 +488,11 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
is_same<_IterBase, const _CharT*>>::value)
_S_copy(__p, std::__niter_base(__k1), __k2 - __k1);
#if __cpp_lib_concepts
- else if constexpr (contiguous_iterator<_Iterator>
- && is_same_v<iter_value_t<_Iterator>, _CharT>)
+ else if constexpr (requires {
+ requires contiguous_iterator<_Iterator>;
+ { std::to_address(__k1) }
+ -> convertible_to<const _CharT*>;
+ })
{
const auto __d = __k2 - __k1;
(void) (__k1 + __d); // See P3349R1
@@ -499,7 +502,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
else
#endif
for (; __k1 != __k2; ++__k1, (void)++__p)
- traits_type::assign(*__p, *__k1); // These types are off.
+ traits_type::assign(*__p, static_cast<_CharT>(*__k1));
}
#pragma GCC diagnostic pop
@@ -527,12 +530,19 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
static constexpr void
_S_copy_range(pointer __p, _Rg&& __rg, size_type __n)
{
- if constexpr (ranges::contiguous_range<_Rg>
- && is_same_v<ranges::range_value_t<_Rg>, _CharT>)
+ if constexpr (requires {
+ requires ranges::contiguous_range<_Rg>;
+ { ranges::data(std::forward<_Rg>(__rg)) }
+ -> convertible_to<const _CharT*>;
+ })
_S_copy(__p, ranges::data(std::forward<_Rg>(__rg)), __n);
else
- for (auto&& __e : __rg)
- traits_type::assign(*__p++, std::forward<decltype(__e)>(__e));
+ {
+ auto __first = ranges::begin(__rg);
+ const auto __last = ranges::end(__rg);
+ for (; __first != __last; ++__first)
+ traits_type::assign(*__p++, static_cast<_CharT>(*__first));
+ }
}
#endif
diff --git a/libstdc++-v3/include/bits/cow_string.h
b/libstdc++-v3/include/bits/cow_string.h
index b250397151b..f9df2be20be 100644
--- a/libstdc++-v3/include/bits/cow_string.h
+++ b/libstdc++-v3/include/bits/cow_string.h
@@ -423,7 +423,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
_S_copy_chars(_CharT* __p, _Iterator __k1, _Iterator __k2)
{
for (; __k1 != __k2; ++__k1, (void)++__p)
- traits_type::assign(*__p, *__k1); // These types are off.
+ traits_type::assign(*__p, static_cast<_CharT>(*__k1));
}
static void
@@ -656,12 +656,19 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
reserve(__n);
pointer __p = _M_data();
- if constexpr (ranges::contiguous_range<_Rg>
- && is_same_v<ranges::range_value_t<_Rg>, _CharT>)
+ if constexpr (requires {
+ requires ranges::contiguous_range<_Rg>;
+ { ranges::data(std::forward<_Rg>(__rg)) }
+ -> convertible_to<const _CharT*>;
+ })
_M_copy(__p, ranges::data(std::forward<_Rg>(__rg)), __n);
else
- for (auto&& __e : __rg)
- traits_type::assign(*__p++, std::forward<decltype(__e)>(__e));
+ {
+ auto __first = ranges::begin(__rg);
+ const auto __last = ranges::end(__rg);
+ for (; __first != __last; ++__first)
+ traits_type::assign(*__p++, static_cast<_CharT>(*__first));
+ }
_M_rep()->_M_set_length_and_sharable(__n);
}
else
diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/cons/char/119748.cc
b/libstdc++-v3/testsuite/21_strings/basic_string/cons/char/119748.cc
new file mode 100644
index 00000000000..f0c0e1fbec3
--- /dev/null
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/cons/char/119748.cc
@@ -0,0 +1,11 @@
+// { dg-do compile }
+
+// Bug 119748
+// string(InputIterator, InputIterator) rejects volatile charT* as iterator
+
+#include <string>
+volatile char vs[42] = {};
+std::string s(vs+0, vs+42);
+#ifdef __cpp_lib_containers_ranges
+std::string s2(std::from_range, vs);
+#endif
diff --git
a/libstdc++-v3/testsuite/21_strings/basic_string/cons/wchar_t/119748.cc
b/libstdc++-v3/testsuite/21_strings/basic_string/cons/wchar_t/119748.cc
new file mode 100644
index 00000000000..715c17588bc
--- /dev/null
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/cons/wchar_t/119748.cc
@@ -0,0 +1,11 @@
+// { dg-do compile }
+
+// Bug 119748
+// string(InputIterator, InputIterator) rejects volatile charT* as iterator
+
+#include <string>
+volatile wchar_t vs[42] = {};
+std::wstring s(vs+0, vs+42);
+#ifdef __cpp_lib_containers_ranges
+std::wstring s2(std::from_range, vs);
+#endif
--
2.49.0
