From dc38e255242192303ae463a913c060b426eb06c0 Mon Sep 17 00:00:00 2001 From: Jonathan Wakely Date: Wed, 14 Oct 2020 11:52:26 +0100 Subject: [PATCH] libstdc++: Implement LWG 3706 for COW strings The basic_string deduction guides are defined for the old ABI, but the tests are currently disabled. This is because a single case fails when using the old ABI, which is just because LWG 3706 isn't implemented for the old ABI. That can be done easily, and the tests can be enabled. libstdc++-v3/ChangeLog: * include/bits/basic_string.h [!_GLIBCXX_USE_CXX11_ABI] (basic_string(const _CharT*, const _Alloc&)): Constrain to require an allocator-like type to fix CTAD ambiguity (LWG 3706). * testsuite/21_strings/basic_string/cons/char/deduction.cc: Remove dg-skip-if. * testsuite/21_strings/basic_string/cons/wchar_t/deduction.cc: Likewise. --- libstdc++-v3/include/bits/basic_string.h | 7 +++++++ .../21_strings/basic_string/cons/char/deduction.cc | 1 - .../21_strings/basic_string/cons/wchar_t/deduction.cc | 1 - 3 files changed, 7 insertions(+), 2 deletions(-) diff --git a/libstdc++-v3/include/bits/basic_string.h b/libstdc++-v3/include/bits/basic_string.h index a9fe09f2069..4b3722bdbf1 100644 --- a/libstdc++-v3/include/bits/basic_string.h +++ b/libstdc++-v3/include/bits/basic_string.h @@ -3612,12 +3612,19 @@ _GLIBCXX_END_NAMESPACE_CXX11 */ basic_string(const _CharT* __s, size_type __n, const _Alloc& __a = _Alloc()); + /** * @brief Construct string as copy of a C string. * @param __s Source C string. * @param __a Allocator to use (default is default allocator). */ +#if __cpp_deduction_guides && ! defined _GLIBCXX_DEFINING_STRING_INSTANTIATIONS + // _GLIBCXX_RESOLVE_LIB_DEFECTS + // 3076. basic_string CTAD ambiguity + template> +#endif basic_string(const _CharT* __s, const _Alloc& __a = _Alloc()); + /** * @brief Construct string as multiple characters. * @param __n Number of characters. diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/cons/char/deduction.cc b/libstdc++-v3/testsuite/21_strings/basic_string/cons/char/deduction.cc index 6484ed43453..d05c4b776c3 100644 --- a/libstdc++-v3/testsuite/21_strings/basic_string/cons/char/deduction.cc +++ b/libstdc++-v3/testsuite/21_strings/basic_string/cons/char/deduction.cc @@ -17,7 +17,6 @@ // { dg-options "-std=gnu++17" } // { dg-do compile { target c++17 } } -// { dg-xfail-if "COW string missing deduction guides" { ! cxx11-abi } } #include #include diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/cons/wchar_t/deduction.cc b/libstdc++-v3/testsuite/21_strings/basic_string/cons/wchar_t/deduction.cc index 373b2b24bdd..1773be28e37 100644 --- a/libstdc++-v3/testsuite/21_strings/basic_string/cons/wchar_t/deduction.cc +++ b/libstdc++-v3/testsuite/21_strings/basic_string/cons/wchar_t/deduction.cc @@ -17,7 +17,6 @@ // { dg-options "-std=gnu++17" } // { dg-do compile { target c++17 } } -// { dg-xfail-if "COW string missing deduction guides" { ! cxx11-abi } } #include #include -- 2.30.2