On 31/07/2024 00:19, Jonathan Wakely wrote:
One more thing that I missed last time, sorry:+#if __glibcxx_string_view >= 202403L + // const string & + string_view + template<typename _CharT, typename _Traits, typename _Alloc> + _GLIBCXX_NODISCARD _GLIBCXX20_CONSTEXPR + inline basic_string<_CharT, _Traits, _Alloc> + operator+(const basic_string<_CharT, _Traits, _Alloc>& __lhs, + __type_identity_t<basic_string_view<_CharT, _Traits>> __rhs) Since this is a C++26 feature, we can use [[nodiscard]] and constexpr unconditionally, so it can be simply: + template<typename _CharT, typename _Traits, typename _Alloc> + [[nodiscard]] + constexpr basic_string<_CharT, _Traits, _Alloc> i.e. use [[nodiscard]] not the NODISCARD macro, and constexpr instead of the CONSTEXPR macro and the inline keyword.
Here's a rebased patch that also includes these changes. Thank you, -- Giuseppe D'Angelo
From fd5570abc94503cadcaa236db1bfa7c5e6cfc404 Mon Sep 17 00:00:00 2001
From: Giuseppe D'Angelo <giuseppe.dang...@kdab.com>
Date: Tue, 30 Jul 2024 20:09:12 +0200
Subject: [PATCH] libstdc++: implement concatenation of strings and
string_views
This adds support for P2591R5, merged for C++26.
libstdc++-v3/ChangeLog:
* include/bits/basic_string.h: Implement the four operator+
overloads between basic_string and (types convertible to)
basic_string_view.
* include/bits/version.def: Bump the feature-testing macro.
* include/bits/version.h: Regenerate.
* testsuite/21_strings/basic_string/operators/char/op_plus_fspath_neg.cc: New test.
* testsuite/21_strings/basic_string/operators/char/op_plus_string_view.cc: New test.
* testsuite/21_strings/basic_string/operators/char/op_plus_string_view_compat.cc:
New test.
Signed-off-by: Giuseppe D'Angelo <giuseppe.dang...@kdab.com>
---
libstdc++-v3/include/bits/basic_string.h | 48 +++++
libstdc++-v3/include/bits/version.def | 5 +
libstdc++-v3/include/bits/version.h | 7 +-
.../operators/char/op_plus_fspath_neg.cc | 13 ++
.../operators/char/op_plus_string_view.cc | 169 ++++++++++++++++++
.../char/op_plus_string_view_compat.cc | 63 +++++++
6 files changed, 304 insertions(+), 1 deletion(-)
create mode 100644 libstdc++-v3/testsuite/21_strings/basic_string/operators/char/op_plus_fspath_neg.cc
create mode 100644 libstdc++-v3/testsuite/21_strings/basic_string/operators/char/op_plus_string_view.cc
create mode 100644 libstdc++-v3/testsuite/21_strings/basic_string/operators/char/op_plus_string_view_compat.cc
diff --git a/libstdc++-v3/include/bits/basic_string.h b/libstdc++-v3/include/bits/basic_string.h
index 120c0bc9a17..7cb2193230c 100644
--- a/libstdc++-v3/include/bits/basic_string.h
+++ b/libstdc++-v3/include/bits/basic_string.h
@@ -3745,6 +3745,54 @@ _GLIBCXX_END_NAMESPACE_CXX11
{ return std::move(__lhs.append(1, __rhs)); }
#endif
+#if __glibcxx_string_view >= 202403L
+ // const string & + string_view
+ template<typename _CharT, typename _Traits, typename _Alloc>
+ [[nodiscard]]
+ constexpr inline basic_string<_CharT, _Traits, _Alloc>
+ operator+(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
+ type_identity_t<basic_string_view<_CharT, _Traits>> __rhs)
+ {
+ typedef basic_string<_CharT, _Traits, _Alloc> _Str;
+ return std::__str_concat<_Str>(__lhs.data(), __lhs.size(),
+ __rhs.data(), __rhs.size(),
+ __lhs.get_allocator());
+ }
+
+ // string && + string_view
+ template<typename _CharT, typename _Traits, typename _Alloc>
+ [[nodiscard]]
+ constexpr inline basic_string<_CharT, _Traits, _Alloc>
+ operator+(basic_string<_CharT, _Traits, _Alloc>&& __lhs,
+ type_identity_t<basic_string_view<_CharT, _Traits>> __rhs)
+ {
+ return std::move(__lhs.append(__rhs));
+ }
+
+ // string_view + const string &
+ template<typename _CharT, typename _Traits, typename _Alloc>
+ [[nodiscard]]
+ constexpr inline basic_string<_CharT, _Traits, _Alloc>
+ operator+(type_identity_t<basic_string_view<_CharT, _Traits>> __lhs,
+ const basic_string<_CharT, _Traits, _Alloc>& __rhs)
+ {
+ typedef basic_string<_CharT, _Traits, _Alloc> _Str;
+ return std::__str_concat<_Str>(__lhs.data(), __lhs.size(),
+ __rhs.data(), __rhs.size(),
+ __rhs.get_allocator());
+ }
+
+ // string_view + string &&
+ template<typename _CharT, typename _Traits, typename _Alloc>
+ [[nodiscard]]
+ constexpr inline basic_string<_CharT, _Traits, _Alloc>
+ operator+(type_identity_t<basic_string_view<_CharT, _Traits>> __lhs,
+ basic_string<_CharT, _Traits, _Alloc>&& __rhs)
+ {
+ return std::move(__rhs.insert(0, __lhs));
+ }
+#endif
+
// operator ==
/**
* @brief Test equivalence of two strings.
diff --git a/libstdc++-v3/include/bits/version.def b/libstdc++-v3/include/bits/version.def
index 23478523e0a..d1505c1a0ac 100644
--- a/libstdc++-v3/include/bits/version.def
+++ b/libstdc++-v3/include/bits/version.def
@@ -698,6 +698,11 @@ ftms = {
ftms = {
name = string_view;
+ values = {
+ v = 202403;
+ cxxmin = 26;
+ hosted = yes;
+ };
values = {
v = 201803;
cxxmin = 17;
diff --git a/libstdc++-v3/include/bits/version.h b/libstdc++-v3/include/bits/version.h
index 0fac749d91e..063ce695bef 100644
--- a/libstdc++-v3/include/bits/version.h
+++ b/libstdc++-v3/include/bits/version.h
@@ -774,7 +774,12 @@
#undef __glibcxx_want_shared_ptr_weak_type
#if !defined(__cpp_lib_string_view)
-# if (__cplusplus >= 201703L) && _GLIBCXX_HOSTED
+# if (__cplusplus > 202302L) && _GLIBCXX_HOSTED
+# define __glibcxx_string_view 202403L
+# if defined(__glibcxx_want_all) || defined(__glibcxx_want_string_view)
+# define __cpp_lib_string_view 202403L
+# endif
+# elif (__cplusplus >= 201703L) && _GLIBCXX_HOSTED
# define __glibcxx_string_view 201803L
# if defined(__glibcxx_want_all) || defined(__glibcxx_want_string_view)
# define __cpp_lib_string_view 201803L
diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/operators/char/op_plus_fspath_neg.cc b/libstdc++-v3/testsuite/21_strings/basic_string/operators/char/op_plus_fspath_neg.cc
new file mode 100644
index 00000000000..bf1e09ada1e
--- /dev/null
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/operators/char/op_plus_fspath_neg.cc
@@ -0,0 +1,13 @@
+// { dg-do compile { target c++17 } }
+
+#include <filesystem>
+#include <string>
+
+int main()
+{
+ std::filesystem::path p = "/var/log/";
+ std::string s = "file";
+ // Concatenation of strings and string views (P2591R5)
+ // should not make this possible:
+ p + s; // { dg-error "no match for" "operator+(string,string_view) should not make this possible" }
+}
diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/operators/char/op_plus_string_view.cc b/libstdc++-v3/testsuite/21_strings/basic_string/operators/char/op_plus_string_view.cc
new file mode 100644
index 00000000000..364d5bd5aba
--- /dev/null
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/operators/char/op_plus_string_view.cc
@@ -0,0 +1,169 @@
+// { dg-do run { target c++26 } }
+
+#include <string>
+#include <type_traits>
+#include <utility>
+
+#include <testsuite_hooks.h>
+
+#if !defined(__cpp_lib_string_view) || __cpp_lib_string_view < 202403L
+#error "__cpp_lib_string_view should have been defined to 202403L or more"
+#endif
+
+static_assert(std::is_same_v<decltype(std::declval<std::string>() + std::declval<std::string_view>()), std::string>);
+static_assert(std::is_same_v<decltype(std::declval<std::string &>() + std::declval<std::string_view>()), std::string>);
+static_assert(std::is_same_v<decltype(std::declval<std::string_view>() + std::declval<std::string>()), std::string>);
+static_assert(std::is_same_v<decltype(std::declval<std::string_view>() + std::declval<std::string &>()), std::string>);
+
+struct convertible_to_string_view1
+{
+ constexpr operator std::string_view() const { return "convertible_to_sv1"; }
+};
+
+struct convertible_to_string_view2
+{
+ constexpr operator std::string_view() { return "convertible_to_sv2"; }
+};
+
+struct convertible_to_string_view3
+{
+ constexpr operator std::string_view() { return "convertible_to_sv3 non_const"; }
+ constexpr operator std::string_view() const { return "convertible_to_sv3 const"; }
+};
+
+struct convertible_to_string_view_and_char_star
+{
+ constexpr operator std::string_view() const { return "convertible_to_sv_and_charstar1"; }
+ constexpr operator const char *() const { return "convertible_to_sv_and_charstar2"; }
+};
+
+struct convertible_to_lots
+{
+ constexpr operator std::string_view() const { return "convertible_to_lots1"; }
+ constexpr operator const char *() const { return "convertible_to_lots2"; }
+ constexpr operator std::string() const { return "convertible_to_lots3"; }
+};
+
+using namespace std::literals;
+static_assert( "costa "s + "marbella"sv == "costa marbella"s );
+static_assert( "costa "sv + "marbella"s == "costa marbella"s );
+static_assert( "costa "s + convertible_to_string_view1{} == "costa convertible_to_sv1"s );
+static_assert( "costa "s + convertible_to_string_view2{} == "costa convertible_to_sv2"s );
+static_assert( "costa "s + convertible_to_string_view3{} == "costa convertible_to_sv3 non_const"s );
+static_assert( "costa "s + convertible_to_string_view_and_char_star{} == "costa convertible_to_sv_and_charstar1"s );
+static_assert( "costa "s + convertible_to_lots{} == "costa convertible_to_lots1"s );
+
+void
+test01()
+{
+ std::string str_0("costa ");
+ std::string str_1("marbella");
+
+ std::string tmp;
+
+ std::string_view str_0_view = str_0;
+ std::string_view str_1_view = str_1;
+
+
+ // string + string_view
+ VERIFY( (str_0 + str_1_view) == "costa marbella" );
+ VERIFY( (str_0 + std::as_const(str_1_view)) == "costa marbella" );
+ VERIFY( (str_0 + std::string_view(str_1)) == "costa marbella" );
+ VERIFY( (str_0_view + str_1) == "costa marbella" );
+ VERIFY( (std::as_const(str_0_view) + str_1) == "costa marbella" );
+ VERIFY( (std::string_view(str_0) + str_1) == "costa marbella" );
+ tmp = str_0;
+ VERIFY( (std::move(tmp) + str_1_view) == "costa marbella" );
+ tmp = str_1;
+ VERIFY( (str_0_view + std::move(tmp)) == "costa marbella" );
+
+
+ // convertible to string_view
+ convertible_to_string_view1 conv_string_view1;
+ VERIFY( (str_0 + conv_string_view1) == "costa convertible_to_sv1" );
+ VERIFY( (str_0 + std::as_const(conv_string_view1)) == "costa convertible_to_sv1" );
+ VERIFY( (std::as_const(str_0) + conv_string_view1) == "costa convertible_to_sv1" );
+ VERIFY( (std::as_const(str_0) + std::as_const(conv_string_view1)) == "costa convertible_to_sv1" );
+
+ tmp = str_0;
+ VERIFY( (std::move(tmp) + conv_string_view1) == "costa convertible_to_sv1" );
+ tmp = str_1;
+ VERIFY( (conv_string_view1 + std::move(tmp)) == "convertible_to_sv1marbella" );
+
+ VERIFY( (conv_string_view1 + str_1) == "convertible_to_sv1marbella" );
+ VERIFY( (conv_string_view1 + std::as_const(str_1)) == "convertible_to_sv1marbella" );
+ VERIFY( (std::as_const(conv_string_view1) + str_1) == "convertible_to_sv1marbella" );
+ VERIFY( (std::as_const(conv_string_view1) + std::as_const(str_1)) == "convertible_to_sv1marbella" );
+
+
+ convertible_to_string_view2 conv_string_view2;
+ VERIFY( (str_0 + conv_string_view2) == "costa convertible_to_sv2" );
+ VERIFY( (std::as_const(str_0) + conv_string_view2) == "costa convertible_to_sv2" );
+ tmp = str_0;
+ VERIFY( (std::move(tmp) + conv_string_view2) == "costa convertible_to_sv2" );
+ tmp = str_1;
+ VERIFY( (conv_string_view2 + std::move(tmp)) == "convertible_to_sv2marbella" );
+
+
+ convertible_to_string_view3 conv_string_view3;
+ VERIFY( (str_0 + conv_string_view3) == "costa convertible_to_sv3 non_const" );
+ VERIFY( (str_0 + std::as_const(conv_string_view3)) == "costa convertible_to_sv3 const" );
+ VERIFY( (std::as_const(str_0) + conv_string_view3) == "costa convertible_to_sv3 non_const" );
+ VERIFY( (std::as_const(str_0) + std::as_const(conv_string_view3)) == "costa convertible_to_sv3 const" );
+
+ tmp = str_0;
+ VERIFY( (std::move(tmp) + conv_string_view3) == "costa convertible_to_sv3 non_const" );
+ tmp = str_1;
+ VERIFY( (conv_string_view3 + std::move(tmp)) == "convertible_to_sv3 non_constmarbella" );
+
+ VERIFY( (conv_string_view3 + str_1) == "convertible_to_sv3 non_constmarbella" );
+ VERIFY( (conv_string_view3 + std::as_const(str_1)) == "convertible_to_sv3 non_constmarbella" );
+ VERIFY( (std::as_const(conv_string_view3) + str_1) == "convertible_to_sv3 constmarbella" );
+ VERIFY( (std::as_const(conv_string_view3) + std::as_const(str_1)) == "convertible_to_sv3 constmarbella" );
+
+
+ convertible_to_string_view_and_char_star conv_sv_cs;
+ VERIFY( (str_0 + conv_sv_cs) == "costa convertible_to_sv_and_charstar1" );
+ VERIFY( (conv_sv_cs + str_1) == "convertible_to_sv_and_charstar1marbella" );
+
+
+ convertible_to_lots conv_lots;
+ VERIFY( (str_0 + conv_lots) == "costa convertible_to_lots1" );
+ VERIFY( (conv_lots + str_1) == "convertible_to_lots1marbella" );
+
+
+ // Check that we're not regressing common cases
+ // string + string literal
+ VERIFY( (str_0 + "marbella") == "costa marbella" );
+ VERIFY( ("costa " + str_1) == "costa marbella" );
+
+ tmp = str_0;
+ VERIFY( (std::move(tmp) + "marbella") == "costa marbella" );
+ tmp = str_1;
+ VERIFY( ("costa " + std::move(tmp)) == "costa marbella" );
+
+
+ // string + non-const char *
+ VERIFY( (str_0 + str_1.data()) == "costa marbella" );
+ VERIFY( (str_0.data() + str_1) == "costa marbella" );
+
+ tmp = str_0;
+ VERIFY( (std::move(tmp) + str_1.data()) == "costa marbella" );
+ tmp = str_1;
+ VERIFY( (str_0.data() + std::move(tmp)) == "costa marbella" );
+
+
+ // string + const char *
+ VERIFY( (str_0 + std::as_const(str_1).data()) == "costa marbella" );
+ VERIFY( (std::as_const(str_0).data() + str_1) == "costa marbella" );
+
+ tmp = str_0;
+ VERIFY( (std::move(tmp) + std::as_const(str_1).data()) == "costa marbella" );
+ tmp = str_1;
+ VERIFY( (std::as_const(str_0).data() + std::move(tmp)) == "costa marbella" );
+}
+
+int main()
+{
+ test01();
+}
diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/operators/char/op_plus_string_view_compat.cc b/libstdc++-v3/testsuite/21_strings/basic_string/operators/char/op_plus_string_view_compat.cc
new file mode 100644
index 00000000000..d24f9fb2c1d
--- /dev/null
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/operators/char/op_plus_string_view_compat.cc
@@ -0,0 +1,63 @@
+// { dg-do compile { target c++17 } }
+
+#include <string>
+#include <type_traits>
+#include <utility>
+
+#include <testsuite_hooks.h>
+
+// "legacy" string view and operators
+template <typename CharT>
+struct basic_my_string_view
+{
+ std::basic_string_view<CharT> view;
+};
+
+using my_string_view = basic_my_string_view<char>;
+
+template <class T>
+struct my_type_identity { using type = T; };
+template <class T>
+using my_type_identity_t = typename my_type_identity<T>::type;
+
+template <typename CharT, typename T, typename A>
+std::string operator+(const std::basic_string<CharT, T, A> &s, basic_my_string_view<CharT> msv)
+{
+ std::string result = s;
+ result += msv.view;
+ result += " using my_string_view";
+ return result;
+}
+
+template <typename CharT, typename T, typename A>
+std::string operator+(const std::basic_string<CharT, T, A> &s, my_type_identity_t<basic_my_string_view<CharT>> msv)
+{
+ std::string result = s;
+ result += msv.view;
+ result += " using my_string_view";
+ return result;
+}
+
+
+struct buffer
+{
+ std::string buf;
+
+ // "legacy"
+ operator my_string_view() const { return my_string_view{buf}; }
+ // "modern"
+ operator std::string_view() const { return std::string_view{buf}; }
+};
+
+int
+main()
+{
+ std::string s = "costa ";
+ buffer b{"marbella"};
+
+ // This should be ambiguous in C++26 due to new operator+ overloads
+ // between std::string and objects convertible to std::string_view
+ // (P2591R5)
+ std::string result = s + b; // { dg-error "ambiguous" "operator+(string,string_view) should make this ambiguous" { target c++26 } }
+ VERIFY( result == "costa marbella using my_string_view" );
+}
--
2.34.1
smime.p7s
Description: S/MIME Cryptographic Signature
