https://gcc.gnu.org/g:05d3aebe24be1177851574ab224f16492c5050fd
commit r15-9478-g05d3aebe24be1177851574ab224f16492c5050fd
Author: Jonathan Wakely <jwak...@redhat.com>
Date: Fri Apr 11 22:13:14 2025 +0100
libstdc++: Fix std::string construction from volatile char* [PR119748]
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, some generic loops for non-contiguous iterators need an
explicit cast to deal with iterator reference types that do not bind to
the const charT& parameter of traits_type::assign.
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/basic_string.tcc (_M_construct): Use explicit
conversion to charT after dereferencing iterator.
* include/bits/cow_string.h (_S_copy_chars): Likewise.
(basic_string(from_range_t, R&&, const Allocator&)): Likewise.
Only optimize for contiguous iterators that are convertible to
const charT*.
* testsuite/21_strings/basic_string/cons/char/119748.cc: New
test.
* testsuite/21_strings/basic_string/cons/wchar_t/119748.cc:
New test.
Reviewed-by: Tomasz Kaminski <tkami...@redhat.com>
Diff:
---
libstdc++-v3/include/bits/basic_string.h | 24 ++++++++++-----
libstdc++-v3/include/bits/basic_string.tcc | 3 +-
libstdc++-v3/include/bits/cow_string.h | 17 +++++++----
.../21_strings/basic_string/cons/char/119748.cc | 35 ++++++++++++++++++++++
.../21_strings/basic_string/cons/wchar_t/119748.cc | 7 +++++
5 files changed, 73 insertions(+), 13 deletions(-)
diff --git a/libstdc++-v3/include/bits/basic_string.h
b/libstdc++-v3/include/bits/basic_string.h
index 9c431c765ab4..c90bd099b639 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/basic_string.tcc
b/libstdc++-v3/include/bits/basic_string.tcc
index 02230aca5d27..bca55bc56581 100644
--- a/libstdc++-v3/include/bits/basic_string.tcc
+++ b/libstdc++-v3/include/bits/basic_string.tcc
@@ -210,7 +210,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
_M_data(__another);
_M_capacity(__capacity);
}
- traits_type::assign(_M_data()[__len++], *__beg);
+ traits_type::assign(_M_data()[__len++],
+ static_cast<_CharT>(*__beg));
++__beg;
}
diff --git a/libstdc++-v3/include/bits/cow_string.h
b/libstdc++-v3/include/bits/cow_string.h
index b250397151bb..f9df2be20bed 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 000000000000..301ca5ddd8e5
--- /dev/null
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/cons/char/119748.cc
@@ -0,0 +1,35 @@
+// { dg-do compile }
+
+// Bug 119748
+// string(InputIterator, InputIterator) rejects volatile charT* as iterator
+
+#ifndef TEST_CHAR_TYPE
+#define TEST_CHAR_TYPE char
+#endif
+
+#include <string>
+#include <testsuite_iterators.h>
+
+typedef TEST_CHAR_TYPE C;
+
+volatile C vs[42] = {};
+std::basic_string<C> s(vs+0, vs+42);
+#ifdef __cpp_lib_containers_ranges
+std::basic_string<C> s2(std::from_range, vs);
+#endif
+
+using namespace __gnu_test;
+
+test_container<volatile C, input_iterator_wrapper> input_cont(vs);
+std::basic_string<C> s3(input_cont.begin(), input_cont.end());
+
+test_container<volatile C, forward_iterator_wrapper> fwd_cont(vs);
+std::basic_string<C> s4(fwd_cont.begin(), fwd_cont.end());
+
+#ifdef __cpp_lib_containers_ranges
+test_input_range<volatile C> input_range(vs);
+std::basic_string<C> s5(std::from_range, input_range);
+
+test_forward_range<volatile C> fwd_range(vs);
+std::basic_string<C> s6(std::from_range, fwd_range);
+#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 000000000000..7d3ba10d2d43
--- /dev/null
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/cons/wchar_t/119748.cc
@@ -0,0 +1,7 @@
+// { dg-do compile }
+
+// Bug 119748
+// string(InputIterator, InputIterator) rejects volatile charT* as iterator
+
+#define TEST_CHAR_TYPE wchar_t
+#include "../char/119748.cc"
