On 30/07/2024 15:27, Jonathan Wakely wrote:
On Tue, 30 Jul 2024 at 14:08, Jonathan Wakely <jwakely....@gmail.com> wrote:On Tue, 30 Jul 2024 at 08:31, Giuseppe D'Angelo <giuseppe.dang...@kdab.com> wrote:Hello! The attached patch implements adds support for P2591R5 in libstdc++ (concatenation of strings and string_views, approved in Tokyo for C++26).Thanks for this patch as well. This was on my TODO list so I'll be happy to not have to do it myself now!
Thank you for the thorough review and guidance; I hope I have fixed everything, attaching the new patch.
I don't have committing rights, so feel free to grab the patch and apply it at your convenience :)
Thanks, -- Giuseppe D'Angelo
From 83a727ebe119609920480edd7bde5fa635e6c3c3 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 8a695a494ef..51bf657b599 100644
--- a/libstdc++-v3/include/bits/basic_string.h
+++ b/libstdc++-v3/include/bits/basic_string.h
@@ -3742,6 +3742,54 @@ _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>
+ _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)
+ {
+ 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>
+ _GLIBCXX_NODISCARD _GLIBCXX20_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>
+ _GLIBCXX_NODISCARD _GLIBCXX20_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>
+ _GLIBCXX_NODISCARD _GLIBCXX20_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 ad4715048ab..e5cb527728b 100644
--- a/libstdc++-v3/include/bits/version.def
+++ b/libstdc++-v3/include/bits/version.def
@@ -694,6 +694,11 @@ 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 e35254d8202..b918eda3e8b 100644
--- a/libstdc++-v3/include/bits/version.h
+++ b/libstdc++-v3/include/bits/version.h
@@ -769,7 +769,12 @@
#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
