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2025-04-15libstdc++: Fix std::string construction from volatile char* [PR119748]Jonathan Wakely
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 <tkaminsk@redhat.com>
2025-04-04libstdc++: Fix whitespace in std::basic_string::_M_construct<bool>Jonathan Wakely
libstdc++-v3/ChangeLog: * include/bits/basic_string.tcc: Fix whitespace.
2025-03-30Optimize string constructorJan Hubicka
this patch improves code generation on string constructors. We currently have _M_construct which takes as a parameter two iterators (begin/end pointers to other string) and produces new string. This patch adds special case of constructor where instead of begining/end pointers we readily know the string size and also special case when we know that source is 0 terminated. This happens commonly when producing stirng copies. Moreover currently ipa-prop is not able to propagate information that beg-end is known constant (copied string size) which makes it impossible for inliner to spot the common case where string size is known to be shorter than 15 bytes and fits in local buffer. Finally I made new constructor inline. Because it is explicitely instantiated without C++20 constexpr we do not produce implicit instantiation (as required by standard) which prevents inlining, ipa-modref and any other IPA analysis to happen. I think we need to make many of the other functions inline, since optimization accross string manipulation is quite important. There is PR94960 to track this issue. Bootstrapped/regtested x86_64-linux, OK? libstdc++-v3/ChangeLog: PR tree-optimization/103827 PR tree-optimization/80331 PR tree-optimization/87502 * config/abi/pre/gnu.ver: Add version for _M_construct<bool> * include/bits/basic_string.h: (basic_string::_M_construct<bool>): Declare. (basic_string constructors): Use it. * include/bits/basic_string.tcc: (basic_string::_M_construct<bool>): New template. * src/c++11/string-inst.cc: Instantated S::_M_construct<bool>. gcc/testsuite/ChangeLog: * g++.dg/tree-ssa/pr80331.C: New test. * g++.dg/tree-ssa/pr87502.C: New test.
2025-01-02Update copyright years.Jakub Jelinek
2024-09-27libstdc++: Fix -Wsign-compare warning in std::string::resize_for_overwriteJonathan Wakely
libstdc++-v3/ChangeLog: * include/bits/basic_string.tcc (resize_for_overwrite): Fix -Wsign-compare warning. * include/bits/cow_string.h (resize_for_overwrite): Likewise.
2024-09-25libstdc++: #ifdef out #pragma GCC system_headerJason Merrill
In r15-3714-gd3a7302ec5985a I added -Wsystem-headers to the libstdc++ build flags to help catch problems in the library. This patch takes a different approach, of disabling the #pragma system_header unless _GLIBCXX_SYSHDR is defined. As a result, the testsuites will treat them as non-system-headers to get better warning coverage during regression testing of both gcc and libstdc++, not just when building the library. My rationale for the #ifdef instead of just removing the #pragma is the three G++ tests that want to test libstdc++ system header behavior, so we need a way to select it. This doesn't affect installed libraries, as they get their system-header status from the lookup path. But testsuite_flags --build-includes gives -I directives rather than -isystem. This patch doesn't change the headers in config/ because I'm not compiling with most of them, so won't see any warnings that need fixing. Adjusting them could happen later, or we can not bother. libstdc++-v3/ChangeLog: * acinclude.m4 (WARN_FLAGS): Remove -Wsystem-headers. * configure: Regenerate. * include/bits/algorithmfwd.h: #ifdef out #pragma GCC system_header. * include/bits/atomic_base.h * include/bits/atomic_futex.h * include/bits/atomic_timed_wait.h * include/bits/atomic_wait.h * include/bits/basic_ios.h * include/bits/basic_string.h * include/bits/boost_concept_check.h * include/bits/char_traits.h * include/bits/charconv.h * include/bits/chrono.h * include/bits/chrono_io.h * include/bits/codecvt.h * include/bits/concept_check.h * include/bits/cpp_type_traits.h * include/bits/elements_of.h * include/bits/enable_special_members.h * include/bits/erase_if.h * include/bits/forward_list.h * include/bits/functional_hash.h * include/bits/gslice.h * include/bits/gslice_array.h * include/bits/hashtable.h * include/bits/indirect_array.h * include/bits/invoke.h * include/bits/ios_base.h * include/bits/iterator_concepts.h * include/bits/locale_classes.h * include/bits/locale_facets.h * include/bits/locale_facets_nonio.h * include/bits/localefwd.h * include/bits/mask_array.h * include/bits/max_size_type.h * include/bits/memory_resource.h * include/bits/memoryfwd.h * include/bits/move_only_function.h * include/bits/node_handle.h * include/bits/ostream_insert.h * include/bits/out_ptr.h * include/bits/parse_numbers.h * include/bits/postypes.h * include/bits/quoted_string.h * include/bits/range_access.h * include/bits/ranges_base.h * include/bits/refwrap.h * include/bits/sat_arith.h * include/bits/semaphore_base.h * include/bits/slice_array.h * include/bits/std_abs.h * include/bits/std_function.h * include/bits/std_mutex.h * include/bits/std_thread.h * include/bits/stl_iterator_base_funcs.h * include/bits/stl_iterator_base_types.h * include/bits/stl_tree.h * include/bits/stream_iterator.h * include/bits/streambuf_iterator.h * include/bits/stringfwd.h * include/bits/this_thread_sleep.h * include/bits/unique_lock.h * include/bits/uses_allocator_args.h * include/bits/utility.h * include/bits/valarray_after.h * include/bits/valarray_array.h * include/bits/valarray_before.h * include/bits/version.h * include/c_compatibility/fenv.h * include/c_compatibility/inttypes.h * include/c_compatibility/stdint.h * include/decimal/decimal.h * include/experimental/bits/net.h * include/experimental/bits/shared_ptr.h * include/ext/aligned_buffer.h * include/ext/alloc_traits.h * include/ext/atomicity.h * include/ext/concurrence.h * include/ext/numeric_traits.h * include/ext/pod_char_traits.h * include/ext/pointer.h * include/ext/stdio_filebuf.h * include/ext/stdio_sync_filebuf.h * include/ext/string_conversions.h * include/ext/type_traits.h * include/ext/vstring.h * include/ext/vstring_fwd.h * include/ext/vstring_util.h * include/parallel/algorithmfwd.h * include/parallel/numericfwd.h * include/tr1/functional_hash.h * include/tr1/hashtable.h * include/tr1/random.h * libsupc++/exception.h * libsupc++/hash_bytes.h * include/bits/basic_ios.tcc * include/bits/basic_string.tcc * include/bits/fstream.tcc * include/bits/istream.tcc * include/bits/locale_classes.tcc * include/bits/locale_facets.tcc * include/bits/locale_facets_nonio.tcc * include/bits/ostream.tcc * include/bits/sstream.tcc * include/bits/streambuf.tcc * include/bits/string_view.tcc * include/bits/version.tpl * include/experimental/bits/string_view.tcc * include/ext/pb_ds/detail/resize_policy/hash_prime_size_policy_imp.hpp * include/ext/random.tcc * include/ext/vstring.tcc * include/tr2/bool_set.tcc * include/tr2/dynamic_bitset.tcc * include/bits/c++config * include/c/cassert * include/c/cctype * include/c/cerrno * include/c/cfloat * include/c/ciso646 * include/c/climits * include/c/clocale * include/c/cmath * include/c/csetjmp * include/c/csignal * include/c/cstdarg * include/c/cstddef * include/c/cstdio * include/c/cstdlib * include/c/cstring * include/c/ctime * include/c/cuchar * include/c/cwchar * include/c/cwctype * include/c_global/cassert * include/c_global/ccomplex * include/c_global/cctype * include/c_global/cerrno * include/c_global/cfenv * include/c_global/cfloat * include/c_global/cinttypes * include/c_global/ciso646 * include/c_global/climits * include/c_global/clocale * include/c_global/cmath * include/c_global/csetjmp * include/c_global/csignal * include/c_global/cstdalign * include/c_global/cstdarg * include/c_global/cstdbool * include/c_global/cstddef * include/c_global/cstdint * include/c_global/cstdio * include/c_global/cstdlib * include/c_global/cstring * include/c_global/ctgmath * include/c_global/ctime * include/c_global/cuchar * include/c_global/cwchar * include/c_global/cwctype * include/c_std/cassert * include/c_std/cctype * include/c_std/cerrno * include/c_std/cfloat * include/c_std/ciso646 * include/c_std/climits * include/c_std/clocale * include/c_std/cmath * include/c_std/csetjmp * include/c_std/csignal * include/c_std/cstdarg * include/c_std/cstddef * include/c_std/cstdio * include/c_std/cstdlib * include/c_std/cstring * include/c_std/ctime * include/c_std/cuchar * include/c_std/cwchar * include/c_std/cwctype * include/debug/array * include/debug/bitset * include/debug/deque * include/debug/forward_list * include/debug/list * include/debug/map * include/debug/set * include/debug/string * include/debug/unordered_map * include/debug/unordered_set * include/debug/vector * include/decimal/decimal * include/experimental/algorithm * include/experimental/any * include/experimental/array * include/experimental/buffer * include/experimental/chrono * include/experimental/contract * include/experimental/deque * include/experimental/executor * include/experimental/filesystem * include/experimental/forward_list * include/experimental/functional * include/experimental/internet * include/experimental/io_context * include/experimental/iterator * include/experimental/list * include/experimental/map * include/experimental/memory * include/experimental/memory_resource * include/experimental/net * include/experimental/netfwd * include/experimental/numeric * include/experimental/propagate_const * include/experimental/ratio * include/experimental/regex * include/experimental/scope * include/experimental/set * include/experimental/socket * include/experimental/string * include/experimental/string_view * include/experimental/synchronized_value * include/experimental/system_error * include/experimental/timer * include/experimental/tuple * include/experimental/type_traits * include/experimental/unordered_map * include/experimental/unordered_set * include/experimental/vector * include/ext/algorithm * include/ext/cmath * include/ext/functional * include/ext/iterator * include/ext/memory * include/ext/numeric * include/ext/random * include/ext/rb_tree * include/ext/rope * include/parallel/algorithm * include/std/algorithm * include/std/any * include/std/array * include/std/atomic * include/std/barrier * include/std/bit * include/std/bitset * include/std/charconv * include/std/chrono * include/std/codecvt * include/std/complex * include/std/concepts * include/std/condition_variable * include/std/coroutine * include/std/deque * include/std/execution * include/std/expected * include/std/filesystem * include/std/format * include/std/forward_list * include/std/fstream * include/std/functional * include/std/future * include/std/generator * include/std/iomanip * include/std/ios * include/std/iosfwd * include/std/iostream * include/std/istream * include/std/iterator * include/std/latch * include/std/limits * include/std/list * include/std/locale * include/std/map * include/std/memory * include/std/memory_resource * include/std/mutex * include/std/numbers * include/std/numeric * include/std/optional * include/std/ostream * include/std/print * include/std/queue * include/std/random * include/std/ranges * include/std/ratio * include/std/regex * include/std/scoped_allocator * include/std/semaphore * include/std/set * include/std/shared_mutex * include/std/span * include/std/spanstream * include/std/sstream * include/std/stack * include/std/stacktrace * include/std/stdexcept * include/std/streambuf * include/std/string * include/std/string_view * include/std/syncstream * include/std/system_error * include/std/text_encoding * include/std/thread * include/std/tuple * include/std/type_traits * include/std/typeindex * include/std/unordered_map * include/std/unordered_set * include/std/utility * include/std/valarray * include/std/variant * include/std/vector * include/std/version * include/tr1/array * include/tr1/cfenv * include/tr1/cinttypes * include/tr1/cmath * include/tr1/complex * include/tr1/cstdbool * include/tr1/cstdint * include/tr1/cstdio * include/tr1/cstdlib * include/tr1/cwchar * include/tr1/cwctype * include/tr1/functional * include/tr1/memory * include/tr1/random * include/tr1/regex * include/tr1/tuple * include/tr1/type_traits * include/tr1/unordered_map * include/tr1/unordered_set * include/tr1/utility * include/tr2/bool_set * include/tr2/dynamic_bitset * include/tr2/type_traits * libsupc++/atomic_lockfree_defines.h * libsupc++/compare * libsupc++/cxxabi.h * libsupc++/cxxabi_forced.h * libsupc++/cxxabi_init_exception.h * libsupc++/exception * libsupc++/initializer_list * libsupc++/new * libsupc++/typeinfo: Likewise. * testsuite/20_util/ratio/operations/ops_overflow_neg.cc * testsuite/23_containers/array/tuple_interface/get_neg.cc * testsuite/23_containers/vector/cons/destructible_debug_neg.cc * testsuite/24_iterators/operations/prev_neg.cc * testsuite/ext/type_traits/add_unsigned_floating_neg.cc * testsuite/ext/type_traits/add_unsigned_integer_neg.cc * testsuite/ext/type_traits/remove_unsigned_floating_neg.cc * testsuite/ext/type_traits/remove_unsigned_integer_neg.cc: Adjust line numbers. gcc/testsuite/ChangeLog * g++.dg/analyzer/fanalyzer-show-events-in-system-headers-default.C * g++.dg/analyzer/fanalyzer-show-events-in-system-headers-no.C * g++.dg/diagnostic/disable.C: #define _GLIBCXX_SYSHDR.
2024-09-19libstdc++: add #pragma diagnosticJason Merrill
The use of #pragma GCC system_header in libstdc++ has led to bugs going undetected for a while due to the silencing of compiler warnings that would have revealed them promptly, and also interferes with warnings about problematic template instantiations induced by user code. But removing it, or even compiling with -Wsystem-header, is also problematic due to warnings about deliberate uses of extensions. So this patch adds #pragma GCC diagnostic as needed to suppress these warnings. The change to acinclude.m4 changes -Wabi to warn only in comparison to ABI 19, to avoid lots of warnings that we now mangle concept requirements, which are in any case still experimental. I checked for any other changes against ABI v15, and found only the <format> lambda mangling, which we can ignore. This also enables -Wsystem-headers while building the library, so we see any warnings not silenced by these #pragmas. libstdc++-v3/ChangeLog: * include/bits/algorithmfwd.h: * include/bits/allocator.h: * include/bits/codecvt.h: * include/bits/concept_check.h: * include/bits/cpp_type_traits.h: * include/bits/hashtable.h: * include/bits/iterator_concepts.h: * include/bits/ostream_insert.h: * include/bits/ranges_base.h: * include/bits/regex_automaton.h: * include/bits/std_abs.h: * include/bits/stl_algo.h: * include/c_compatibility/fenv.h: * include/c_compatibility/inttypes.h: * include/c_compatibility/stdint.h: * include/ext/concurrence.h: * include/ext/type_traits.h: * testsuite/ext/type_traits/add_unsigned_floating_neg.cc: * testsuite/ext/type_traits/add_unsigned_integer_neg.cc: * testsuite/ext/type_traits/remove_unsigned_floating_neg.cc: * testsuite/ext/type_traits/remove_unsigned_integer_neg.cc: * include/bits/basic_ios.tcc: * include/bits/basic_string.tcc: * include/bits/fstream.tcc: * include/bits/istream.tcc: * include/bits/locale_classes.tcc: * include/bits/locale_facets.tcc: * include/bits/ostream.tcc: * include/bits/regex_compiler.tcc: * include/bits/sstream.tcc: * include/bits/streambuf.tcc: * configure: Regenerate. * include/bits/c++config: * include/c/cassert: * include/c/cctype: * include/c/cerrno: * include/c/cfloat: * include/c/climits: * include/c/clocale: * include/c/cmath: * include/c/csetjmp: * include/c/csignal: * include/c/cstdarg: * include/c/cstddef: * include/c/cstdio: * include/c/cstdlib: * include/c/cstring: * include/c/ctime: * include/c/cwchar: * include/c/cwctype: * include/c_global/climits: * include/c_global/cmath: * include/c_global/cstddef: * include/c_global/cstdlib: * include/decimal/decimal: * include/ext/rope: * include/std/any: * include/std/charconv: * include/std/complex: * include/std/coroutine: * include/std/format: * include/std/iomanip: * include/std/limits: * include/std/numbers: * include/tr1/functional: * include/tr1/tuple: * include/tr1/type_traits: * libsupc++/compare: * libsupc++/new: Add #pragma GCC diagnostic to suppress undesired warnings. * acinclude.m4: Change -Wabi version from 2 to 19. gcc/ChangeLog: * ginclude/stdint-wrap.h: Add #pragma GCC diagnostic to suppress undesired warnings. * gsyslimits.h: Likewise.
2024-01-03Update copyright years.Jakub Jelinek
2023-11-16libstdc++: Only declare feature test macros in standard headersJonathan Wakely
This change moves the definitions of feature test macros (or strictly speaking, the requests for <bits/version.h> to define them) so that only standard headers define them. For example, <bits/shared_ptr.h> will no longer define macros related to std::shared_ptr, only <memory> and <version> will define them. This means that __cpp_lib_shared_ptr_arrays will not be defined by <future> or by other headers that include <bits/shared_ptr.h>. It will only be defined when <memory> has been included. This will discourage users from relying on transitive includes. As a result, internal headers that need to query the macros should use the internal macros like __glibcxx_shared_ptr_arrays instead of __cpp_lib_shared_ptr_arrays, as those internal macros are defined by the internal headers after icluding <bits/version.h>. There are some exceptions to this rule, because __cpp_lib_is_constant_evaluated is defined by bits/c++config.h and so is available everywhere, and __cpp_lib_three_way_comparison is defined by <compare> which several headers are explicitly specified to include, so its macro is guaranteed to be usable too. N.B. not many internal headers actually need an explicit include of <bits/version.h>, because most of them include <type_traits> and so get all the __glibcxx_foo internal macros from there. libstdc++-v3/ChangeLog: * include/bits/algorithmfwd.h: Do not define standard feature test macro here. * include/bits/align.h: Likewise. Test internal macros instead of standard macros. * include/bits/alloc_traits.h: Likewise. * include/bits/allocator.h: Likewise. * include/bits/atomic_base.h: Likewise. * include/bits/atomic_timed_wait.h: Likewise. * include/bits/atomic_wait.h: Likewise. * include/bits/basic_string.h: Likewise. * include/bits/basic_string.tcc: Likewise. * include/bits/char_traits.h: Likewise. * include/bits/chrono.h: Likewise. * include/bits/cow_string.h: Likewise. * include/bits/forward_list.h: Likewise. * include/bits/hashtable.h: Likewise. * include/bits/ios_base.h: Likewise. * include/bits/memory_resource.h: Likewise. * include/bits/move.h: Likewise. * include/bits/move_only_function.h: Likewise. * include/bits/node_handle.h: Likewise. * include/bits/ptr_traits.h: Likewise. * include/bits/range_access.h: Likewise. * include/bits/ranges_algo.h: Likewise. * include/bits/ranges_cmp.h: Likewise. * include/bits/ranges_util.h: Likewise. * include/bits/semaphore_base.h: Likewise. * include/bits/shared_ptr.h: Likewise. * include/bits/shared_ptr_atomic.h: Likewise. * include/bits/shared_ptr_base.h: Likewise. * include/bits/stl_algo.h: Likewise. * include/bits/stl_algobase.h: Likewise. * include/bits/stl_function.h: Likewise. * include/bits/stl_iterator.h: Likewise. * include/bits/stl_list.h: Likewise. * include/bits/stl_map.h: Likewise. * include/bits/stl_pair.h: Likewise. * include/bits/stl_queue.h: Likewise. * include/bits/stl_stack.h: Likewise. * include/bits/stl_tree.h: Likewise. * include/bits/stl_uninitialized.h: Likewise. * include/bits/stl_vector.h: Likewise. * include/bits/unique_ptr.h: Likewise. * include/bits/unordered_map.h: Likewise. * include/bits/uses_allocator_args.h: Likewise. * include/bits/utility.h: Likewise. * include/bits/erase_if.h: Add comment. * include/std/algorithm: Define standard feature test macros here. * include/std/atomic: Likewise. * include/std/array: Likewise. * include/std/chrono: Likewise. * include/std/condition_variable: Likewise. * include/std/deque: Likewise. * include/std/format: Likewise. * include/std/functional: Likewise. * include/std/forward_list: Likewise. * include/std/ios: Likewise. * include/std/iterator: Likewise. * include/std/list: Likewise. * include/std/map: Likewise. * include/std/memory: Likewise. * include/std/numeric: Likewise. * include/std/queue: Likewise. * include/std/ranges: Likewise. * include/std/regex: Likewise. * include/std/set: Likewise. * include/std/stack: Likewise. * include/std/stop_token: Likewise. * include/std/string: Likewise. * include/std/string_view: * include/std/tuple: Likewise. * include/std/unordered_map: * include/std/unordered_set: * include/std/utility: Likewise. * include/std/vector: Likewise. * include/std/scoped_allocator: Query internal macros instead of standard macros.
2023-10-21libstdc++: Split std::basic_string::_M_use_local_data into two functionsJonathan Wakely
This splits out the activate-the-union-member-for-constexpr logic from _M_use_local_data, so that it can be used separately in cases that don't need to use std::pointer_traits<pointer>::pointer_to to obtain the return value. This leaves only three uses of _M_use_local_data() which are all of the same form: __s._M_data(_M_use_local_data()); __s._M_set_length(0); We could remove _M_use_local_data() and change those three places to use a new _M_reset() function that does: _M_init_local_buf(); _M_data(_M_local_data()); _M_set_length(0); This is left for a future change. libstdc++-v3/ChangeLog: * include/bits/basic_string.h (_M_init_local_buf()): New function. (_M_use_local_data()): Use _M_init_local_buf. (basic_string(), basic_string(const Alloc&)) (basic_string(basic_string&&)) (basic_string(basic_string&&, const Alloc&)): Use _M_init_local_buf instead of _M_use_local_data(). * include/bits/basic_string.tcc (swap(basic_string&)) (_M_construct(InIter, InIter, input_iterator_tag)) (_M_construct(InIter, InIter, forward_iterator_tag)) (_M_construct(size_type, CharT), reserve()): Likewise.
2023-09-29libstdc++: Ensure active union member is correctly setNathaniel Shead
This patch ensures that the union members for std::string and std::variant are always properly set when a change occurs. libstdc++-v3/ChangeLog: * include/bits/basic_string.h: (basic_string(basic_string&&)): Activate _M_local_buf when needed. (basic_string(basic_string&&, const _Alloc&)): Likewise. * include/bits/basic_string.tcc: (basic_string::swap): Likewise. * include/std/variant: (__detail::__variant::__construct_n): New. (__detail::__variant::__emplace): Use __construct_n. Signed-off-by: Nathaniel Shead <nathanieloshead@gmail.com>
2023-08-17libstdc++: Define std::string::resize_and_overwrite for C++11 and COW stringJonathan Wakely
There are several places in the library where we can improve performance using resize_and_overwrite so it's inconvenient only being able to use it in C++23 mode, and only for cxx11 strings. This adds it for COW strings, and also adds __resize_and_overwrite as an extension for C++11 mode. The new __resize_and_overwrite is available for C++11 and later, so within the library we can use that consistently even in C++23. In order to avoid making a copy (which might not be possible for non-copyable, non-movable types) the callable is passed to resize_and_overwrite as an lvalue reference. Unlike wrapping it in std::ref(op) this ensures that invoking it as std::move(op)(n, p) will use the correct value category. It also avoids any overhead that would be added by wrapping it in a lambda like [&op](auto p, auto n) { return std::move(op)(p, n); }. Adjust std::format to use the new __resize_and_overwrite, which we can assume exists because we only use std::basic_string<char> and std::basic_string<wchar_t>, so no program-defined specializations. The uses in <experimental/internet> cannot be replaced, because those are type-dependent on an Allocator template parameter, which could mean they use program-defined specializations of std::basic_string that don't have the __resize_and_overwrite extension. libstdc++-v3/ChangeLog: * include/bits/basic_string.h (__resize_and_overwrite): New function. * include/bits/basic_string.tcc (__resize_and_overwrite): New function. (resize_and_overwrite): Simplify by using reserve instead of growing the string manually. Adjust for C++11 compatibility. * include/bits/cow_string.h (resize_and_overwrite): New function. (__resize_and_overwrite): New function. * include/bits/version.def (__cpp_lib_string_resize_and_overwrite): Do not depend on cxx11abi. * include/bits/version.h: Regenerate. * include/std/format (__formatter_fp::_S_resize_and_overwrite): Remove. (__formatter_fp::format, __formatter_fp::_M_localize): Use __resize_and_overwrite instead of _S_resize_and_overwrite. * testsuite/21_strings/basic_string/capacity/char/resize_and_overwrite.cc: Adjust for C++11 compatibility when included by ... * testsuite/21_strings/basic_string/capacity/char/resize_and_overwrite_ext.cc: New test.
2023-08-16libstdc++: Fix std::basic_string::resize_and_overwriteJonathan Wakely
The callable used for resize_and_overwrite was being passed the string's expanded capacity, which might be greater than the new size being requested. This is not conforming, as the standard requires the same n to be passed to the callable that the user passed to resize_and_overwrite. The existing tests didn't catch this because they all used a value which was more than twice the existing capacity, so the _M_create call allocated exactly what was requested, and the value passed to the callable was correct. But when the requested size is greater than the current capacity but smaller than twice the current capacity, _M_create will allocate twice the current capacity and then that value was being passed to the callable. I noticed this because std::format(L"{}", 0.25) was producing L"0.25XX" where the XX characters were whatever happened to be on the stack before the call. When std::format used resize_and_overwrite to widen a string it was copying too many characters into the destination and setting the result's length too long. I've added a test for this case, and a new test that doesn't hardcode -std=gnu++20 so can be used to test std::format in C++23 and C++26 modes. libstdc++-v3/ChangeLog: * include/bits/basic_string.tcc (resize_and_overwrite): Invoke the callable with the same size as resize_and_overwrite was called with. * testsuite/21_strings/basic_string/capacity/char/resize_and_overwrite.cc: Check with small values for the new size. * testsuite/std/format/functions/format.cc: Check wide formatting of double values that produce small strings. * testsuite/std/format/functions/format_c++23.cc: New test.
2023-05-11libstdc++: Enforce value_type consistency in strings and streamsJonathan Wakely
P1463R1 made it ill-formed for allocator-aware containers (including std::basic_string) to use an allocator that has a different value_type from the container itself. We already enforce that for other containers (since r8-4828-g866e4d3853ccc0), but not for std::basic_string. We traditionally accepted it as an extension and rebound the allocator, so this change only adds the enforcement for C++20 and later. Similarly, P1148R0 made it ill-formed for strings and streams to use a traits type that has an incorrect char_type. We already enforce that for std::basic_string_view, so we just need to add it to std::basic_ios and std::basic_string. The assertion for the allocator's value_type caused some testsuite regressions: FAIL: 21_strings/basic_string/cons/char/deduction.cc (test for excess errors) FAIL: 21_strings/basic_string/cons/wchar_t/deduction.cc (test for excess errors) FAIL: 21_strings/basic_string/requirements/explicit_instantiation/debug.cc (test for excess errors) FAIL: 21_strings/basic_string/requirements/explicit_instantiation/int.cc (test for excess errors) The last two are testing the traditional extension that rebinds the allocator, so need to be disabled for C++20. The first two are similar to LWG 3076 where an incorrect constructor is considered for CTAD. In this case, determining that it's not viable requires instantiating std::basic_string<Iter, char_traits<Iter>, Alloc> which then fails the new assertion, because Alloc::value_type is not the same as Iter. This is only a problem because the size_type parameter of the non-viable constructor is an alias for _Alloc_traits_impl<A>::size_type which is a nested type, and so the enclosing basic_string specialization needs to be instantiated. If we remove the _Alloc_traits_impl wrapper that was added in r12-5413-g2d76292bd6719d, then the definition of size_type no longer depends on basic_string, and we don't instantiate an invalid specialization and don't fail the assertion. The work done by _Alloc_traits_impl::allocate can be done in a _S_allocate function instead, which is probably more efficient to compile anyway. libstdc++-v3/ChangeLog: * config/abi/pre/gnu.ver: Export basic_string::_S_allocate. * include/bits/basic_ios.h: Add static assertion checking traits_type::value_type. * include/bits/basic_string.h: Likewise. Do not rebind allocator, and add static assertion checking its value_type. (basic_string::_Alloc_traits_impl): Remove class template. (basic_string::_S_allocate): New static member function. (basic_string::assign): Use _S_allocate. * include/bits/basic_string.tcc (basic_string::_M_create) (basic_string::reserve, basic_string::_M_replace): Likewise. * testsuite/21_strings/basic_string/requirements/explicit_instantiation/debug.cc: Disable for C++20 and later. * testsuite/21_strings/basic_string/requirements/explicit_instantiation/int.cc: Likweise.
2023-03-22libstdc++: Use rvalues in std::string::resize_and_overwrite (LWG 3645)Jonathan Wakely
Previously the C++23 draft required that the callback arguments were lvalues, which was overvable by the callback. LWG 3645 removes that overspecification, so we can pass rvalues and the user can't modify our local variables. I've used auto(p) to produce rvalues, which is only supported since Clang 15, but I think that's OK for a C++23 feature. While making this change I noticed that we weren't correctly enforcing the requirement that the callback returns an integer-like type. Add better assertions for the type and value. libstdc++-v3/ChangeLog: * include/bits/basic_string.tcc (basic_string::resize_and_overwrite): Pass rvalues to the callback, as now allowed by LWG 3645. Enforce preconditions on the return value. * testsuite/21_strings/basic_string/capacity/char/resize_and_overwrite.cc: Adjust.
2023-01-16Update copyright years.Jakub Jelinek
2022-11-08libstdc++: Refactor implementation of operator+ for std::stringWill Hawkins
Until now operator+(char*, string) and operator+(string, char*) had different performance characteristics. The former required a single memory allocation and the latter required two. This patch makes the performance equal. After consultation with Jonathan, it seemed like a good idea to create a single function that performed one-allocation string concatenation that could be used by various different version of operator+. This patch adds such a function and calls it from the relevant implementations. Co-authored-by: Jonathan Wakely <jwakely@redhat.com> libstdc++-v3/ChangeLog: * include/bits/basic_string.h (__str_cat): Add common function that performs single-allocation string concatenation. (operator+): Use __str_cat. * include/bits/basic_string.tcc (operator+): Move to .h and define inline using __str_cat. Signed-off-by: Will Hawkins <whh8b@obs.cr>
2022-09-12libstdc++: Outline the overlapping case of string _M_replace into a separate ↵Jakub Jelinek
function [PR105329] The following patch is partially a workaround for bogus warnings when the compiler isn't able to fold _M_disjunct call into constant false, but also an optimization attempt - assuming _M_disjunct (__s) is rare, the patch should shrink code size for the common case and use library or for non-standard instantiations an out of line function to handle the rare case. 2022-09-12 Jakub Jelinek <jakub@redhat.com> PR tree-optimization/105329 * acinclude.m4 (libtool_VERSION): Change to 6:31:0. * config/abi/pre/gnu.ver (GLIBCXX_3.4.21): Don't export std::basic_string methods with name length of 15. (GLIBCXX_3.4.31): Export std::basic_string::_M_replace_cold. * testsuite/util/testsuite_abi.cc (check_version): Handle GLIBCXX_3.4.31. * include/bits/basic_string.h (std::basic_string::_M_replace_cold): Declare. * include/bits/basic_string.tcc (std::basic_string::_M_replace_cold): Define and export even for C++20. (std::basic_string::_M_replace): Use __builtin_expect, outline the overlapping case to _M_replace_cold. * configure: Regenerated.
2022-08-24Revert "libstdc++: Optimize operator+(string/char*, char*/string) equally"Jonathan Wakely
This reverts commit 0b7c9254998b3fb2c39f6b86b5b196f415530205.
2022-08-24libstdc++: Optimize operator+(string/char*, char*/string) equallyWill Hawkins
Until now operator+(char*, const string&) and operator+(const string&, char*) had different performance characteristics. The former required a single memory allocation and the latter required two. This patch makes the performance equal. libstdc++-v3/ChangeLog: * include/bits/basic_string.h (operator+(const string&, const char*)): Remove naive implementation. * include/bits/basic_string.tcc (operator+(const string&, const char*)): Add single-allocation implementation. Signed-off-by: Will Hawkins <whh8b@obs.cr>
2022-06-14libstdc++: Inline all basic_string::compare overloads [PR59048]Jonathan Wakely
Defining the compare member functions inline allows calls to traits_type::length and std::min to be inlined, taking advantage of constant expression arguments. When not inline, the compiler prefers to use the explicit instantiation definitions in libstdc++.so and can't take advantage of constant arguments. libstdc++-v3/ChangeLog: PR libstdc++/59048 * include/bits/basic_string.h (compare): Define inline. * include/bits/basic_string.tcc (compare): Remove out-of-line definitions. * include/bits/cow_string.h (compare): Define inline. * testsuite/21_strings/basic_string/operations/compare/char/3.cc: New test.
2022-01-03Update copyright years.Jakub Jelinek
2021-12-01libstdc++: Define std::__is_constant_evaluated() for internal useJonathan Wakely
This adds std::__is_constant_evaluated() as a C++11 wrapper for __builtin_is_constant_evaluated, but just returning false if the built-in isn't supported by the compiler. This allows us to use it throughout the library without checking __has_builtin every time. Some uses in std::vector and std::string can only be constexpr when the std::is_constant_evaluated() function actually works, so we might as well guard them with a relevant macro and call that function directly, rather than the built-in or std::__is_constant_evaluated(). The remaining checks of the __cpp_lib_is_constant_evaluated macro could now be replaced by checking __cplusplus >= 202002 instead, but there's no practical difference. We still need some kind of preprocessor check there anyway. libstdc++-v3/ChangeLog: * doc/doxygen/user.cfg.in (PREDEFINED): Change macro name. * include/bits/allocator.h (allocate, deallocate): Use std::__is_constant_evaluated() unconditionally, instead of checking whether std::is_constant_evaluated() (or the built-in) can be used. * include/bits/basic_string.h: Check new macro. call std::is_constant_evaluated() directly in C++20-only code that is guarded by a suitable macro. * include/bits/basic_string.tcc: Likewise. * include/bits/c++config (__is_constant_evaluated): Define. (_GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED): Replace with ... (_GLIBCXX_HAVE_IS_CONSTANT_EVALUATED): New macro. * include/bits/char_traits.h (char_traits): Replace conditional calls to std::is_constant_evaluated with unconditional calls to std::__is_constant_evaluated. * include/bits/cow_string.h: Use new macro. * include/bits/ranges_algobase.h (__copy_or_move): Replace conditional calls to std::is_constant_evaluated with unconditional calls to std::__is_constant_evaluated. (__copy_or_move_backward, __fill_n_fn): Likewise. * include/bits/ranges_cmp.h (ranges::less): Likewise. * include/bits/stl_algobase.h (lexicographical_compare_three_way): Likewise. * include/bits/stl_bvector.h: Call std::is_constant_evaluated directly in C++20-only code that is guarded by a suitable macro. * include/bits/stl_construct.h (_Construct, _Destroy, _Destroy_n): Replace is_constant_evaluated with __is_constant_evaluated. * include/bits/stl_function.h (greater, less, greater_equal) (less_equal): Replace __builtin_is_constant_evaluated and __builtin_constant_p with __is_constant_evaluated. * include/bits/stl_vector.h: Call std::is_constant_evaluated() in C++20-only code. * include/debug/helper_functions.h (__check_singular): Use __is_constant_evaluated instead of built-in, or remove check entirely. * include/std/array (operator<=>): Use __is_constant_evaluated unconditionally. * include/std/bit (__bit_ceil): Likewise. * include/std/type_traits (is_constant_evaluated): Define using 'if consteval' if possible. * include/std/version: Use new macro. * libsupc++/compare: Use __is_constant_evaluated instead of __builtin_is_constant_evaluated. * testsuite/23_containers/array/tuple_interface/get_neg.cc: Adjust dg-error lines.
2021-11-19libstdc++: One more change for Clang to support constexpr std::string [PR103295]Jonathan Wakely
All writes into the allocated buffer need to be via traits_type::assign to begin lifetimes. libstdc++-v3/ChangeLog: PR libstdc++/103295 * include/bits/basic_string.tcc (_M_construct): Use the traits assign member to write into allcoated memory.
2021-11-19libstdc++: Begin lifetime of chars in constexpr std::string [PR103295]Jonathan Wakely
Clang gives errors for constexpr std::string because the memory returned by std::allocator<T>::allocate does not contain any objects yet, and attempting to set them using char_traits::assign or char_traits::copy fails with: assignment to object outside its lifetime is not allowed in a constant expression *__result = *__first; ^ This adds code to std::char_traits to use std::construct_at to begin lifetimes when called during constant evaluation. To support specializations of std::basic_string that don't use std::char_traits there is now another layer of wrapper around the allocator_traits, so that the lifetime of characters is begun as soon as the memory is allocated. By doing it in the char traits and allocator traits, the rest of basic_string can ignore the problem. While modifying char_traits::copy and char_traits::assign to begin lifetimes for the constexpr cases, I also replaced their uses of std::copy and std::fill_n respectively. That means we don't need <bits/stl_algobase.h> for char_traits. libstdc++-v3/ChangeLog: PR libstdc++/103295 * include/bits/basic_string.h (_Alloc_traits): Replace typedef with struct for C++20 mode. * include/bits/basic_string.tcc (_M_replace): Use _Alloc_traits for allocation. * include/bits/char_traits.h (__gnu_cxx::char_traits::assign): Use std::_Construct during constant evaluation. (__gnu_cxx::char_traits::assign(CharT*, const CharT*, size_t)): Likewise. Replace std::fill_n with memset or manual loop. (__gnu_cxx::char_traits::copy): Likewise, replacing std::copy with memcpy. * include/ext/vstring.h: Include <bits/stl_algobase.h> for std::min. * include/std/string_view: Likewise. * testsuite/21_strings/basic_string/capacity/char/resize_and_overwrite.cc: Add constexpr test.
2021-11-17libstdc++: Simplify std::string constructorsJonathan Wakely
Several std::basic_string constructors dispatch to one of the two-argument overloads of _M_construct, which then dispatches again to _M_construct_aux to detect whether the arguments are iterators or not. That then dispatches to one of _M_construct(size_type, char_type) or _M_construct(Iter, Iter, iterator_traits<Iter>::iterator_category{}). For most of those constructors this is a waste of time, because we know the arguments are already iterators. For basic_string(const CharT*) and basic_string(initializer_list<C>) we know that we call _M_construct with two pointers, and for basic_string(const basic_string&) we call it with two const_iterators. Those constructors can call the three-argument overload of _M_construct with the iterator category tag right away, without the intermediate dispatching. The case where this doesn't apply is basic_string(InputIter, InputIter), but for C++11 and later this is constrained so we know it's an iterator here as well. We can restrict the dispatching in this constructor to only be done for C++98 and to call _M_construct_aux directly, which allows us to remove the two-argument _M_construct(InputIter, InputIter) overload entirely. N.B. When calling the three-arg _M_construct with pointers or string iterators, we pass forward_iterator_tag not random_access_iterator_tag. This is because it makes no difference which overload gets called, and simplifies overload resolution to not have to do a base-to-derived check. If we ever add a new overload of M_construct for random access iterators we would have to revisit this, but that seems unlikely. This patch also moves the __is_null_pointer checks from the three-arg _M_construct into the constructors where a null pointer argument is actually possible. This avoids redundant checks where we know we have a non-null pointer, or don't have a pointer at all. Finally, this patch replaces some try-blocks with an RAII type, so that memory is deallocated during unwinding. This avoids the overhead of catching and rethrowing an exception. libstdc++-v3/ChangeLog: * include/bits/basic_string.h (_M_construct_aux): Only define for C++98. Remove constexpr. (_M_construct_aux_2): Likewise. (_M_construct(InputIter, InputIter)): Remove. (basic_string(const basic_string&)): Call _M_construct with iterator category argument. (basic_string(const basic_string&, size_type, const Alloc&)): Likewise. (basic_string(const basic_string&, size_type, size_type)): Likewise. (basic_string(const charT*, size_type, const Alloc&)): Likewise. Check for null pointer. (basic_string(const charT*, const Alloc&)): Likewise. (basic_string(initializer_list<charT>, const Alloc&)): Call _M_construct with iterator category argument. (basic_string(const basic_string&, const Alloc&)): Likewise. (basic_string(basic_string&&, const Alloc&)): Likewise. (basic_string(_InputIter, _InputIter, const Alloc&)): Likewise for C++11 and later, call _M_construct_aux for C++98. * include/bits/basic_string.tcc (_M_construct(I, I, input_iterator_tag)): Replace try-block with RAII type. (_M_construct(I, I, forward_iterator_tag)): Likewise. Remove __is_null_pointer check.
2021-11-17libstdc++: Set active member of union in std::string [PR103295]Jonathan Wakely
Clang diagnoses that the new constexpr std::string constructors are not usable in constant expressions, because they start to write to members of the union without setting an active member. This adds a new helper function which returns the address of the local buffer after making it the active member. This doesn't fix all problems with Clang, because it still refuses to write to memory returned by the allocator. libstdc++-v3/ChangeLog: PR libstdc++/103295 * include/bits/basic_string.h (_M_use_local_data()): New member function to make local buffer the active member. (assign(const basic_string&)): Use it. * include/bits/basic_string.tcc (_M_construct, reserve()): Likewise.
2021-11-16libstdc++: Implement constexpr std::basic_string for C++20Michael de Lang
This is only supported for the cxx11 ABI, not for COW strings. libstdc++-v3/ChangeLog: * include/bits/basic_string.h (basic_string, operator""s): Add constexpr for C++20. (basic_string::basic_string(basic_string&&)): Only copy initialized portion of the buffer. (basic_string::basic_string(basic_string&&, const Alloc&)): Likewise. * include/bits/basic_string.tcc (basic_string): Add constexpr for C++20. (basic_string::swap(basic_string&)): Only copy initialized portions of the buffers. (basic_string::_M_replace): Add constexpr implementation that doesn't depend on pointer comparisons. * include/bits/cow_string.h: Adjust comment. * include/ext/type_traits.h (__is_null_pointer): Add constexpr. * include/std/string (erase, erase_if): Add constexpr. * include/std/version (__cpp_lib_constexpr_string): Update value. * testsuite/21_strings/basic_string/cons/char/constexpr.cc: New test. * testsuite/21_strings/basic_string/cons/wchar_t/constexpr.cc: New test. * testsuite/21_strings/basic_string/literals/constexpr.cc: New test. * testsuite/21_strings/basic_string/modifiers/constexpr.cc: New test. * testsuite/21_strings/basic_string/modifiers/swap/char/constexpr.cc: New test. * testsuite/21_strings/basic_string/modifiers/swap/wchar_t/constexpr.cc: New test. * testsuite/21_strings/basic_string/version.cc: New test.
2021-10-16libstdc++: Define std::basic_string::resize_and_overwrite for C++23 (P1072R10)Jonathan Wakely
A recently approved change for the C++23 working draft. libstdc++-v3/ChangeLog: * include/bits/basic_string.h (__cpp_lib_string_resize_and_overwrite): Define for C++23. (basic_string::resize_and_overwrite): Declare. * include/bits/basic_string.tcc (basic_string::resize_and_overwrite): Define. * include/std/version (__cpp_lib_resize_and_overwrite): Define for C++23. * testsuite/21_strings/basic_string/capacity/char/resize_and_overwrite.cc: New test.
2021-07-27libstdc++: Move COW string definitions to separate headerJonathan Wakely
This moves the definitions of the COW string to a separate file, so that they don't need to be preprocessed for the common case. We could also move the SSO string definitions to a new file, so that they don't need to be preprocessed for the old ABI case, but that would require more shovel work because there are some parts of <bits/basic_string.h> and <bits/basic_string.tcc> that are common to both definitions. libstdc++-v3/ChangeLog: * include/Makefile.am: Add new header. * include/Makefile.in: Regenerate. * include/bits/basic_string.h [!_GLIBCXX_USE_CXX11_ABI] (basic_string): Move definition of Copy-on-Write string to new file. * include/bits/basic_string.tcc: Likewise. * include/bits/cow_string.h: New file.
2021-04-30libstdc++: Use std::addressof to avoid ADL for operator& [PR 60497]Jonathan Wakely
This is another small step towards avoiding the problems described in PR 60497, by using std::addressof to avoid ADL, so that we don't require all template arguments to be complete. libstdc++-v3/ChangeLog: PR libstdc++/60497 * include/bits/basic_ios.tcc (basic_ios::copyfmt): use std::addressof. * include/bits/basic_string.tcc (basic_string::swap) (basic_string::assign): Likewise. * include/bits/deque.tcc (deque::operator=(const deque&)): Likewise. * include/bits/stl_tree.h (_Rb_tree::operator=(const * _Rb_tree&)): Likewise. * include/bits/vector.tcc (vector::operator=(const vector&)): Likewise.
2021-02-09string: Add a workaround for -Wstringop-overread false positives [PR98465]Jakub Jelinek
In the PR there are several possibilities how to improve _M_disjunct at least in certain cases so that the compiler can figure out at least in some cases where __s is provably disjunct from _M_data() ... _M_data() + this->size() but it is probably GCC 12 material. The false positive warning is on this particular copy, which is done for non-disjunct pointers when __len2 > __len1 and the __s >= __p + __len1, i.e. __s used to point to the characters moved through _S_move a few lines earlier by __len2 - __len1 characters up to make space. That is why the _S_copy source is __s + __len2 - __len1. Unfortunately, when the compiler can't prove objects are disjunct, that copying from __s + __len2 - __len1 of __len2 characters can very well mean accessing characters the source object (if it is not disjunct) provably can't have. The following patch works around that by making the _S_copy be a __p based pointer instead of __s based pointer. __s + __len2 - __len1 and __p + (__s - __p) + (__len2 - __len1) have the same value and the latter may seem to be uselessly longer, but it seems at least currently in GIMPLE we keep it that way and so that is what the warning code during expansion will see, and only actually optimize it to __s + __len2 - __len1 during RTL when we lose information on what is a pointer and what is a mere offset with the same mode. So, in the end we emit exactly the same assembly, just without the false positive warning. 2021-02-09 Jakub Jelinek <jakub@redhat.com> PR middle-end/98465 * include/bits/basic_string.tcc (basic_string::_M_replace): When __s points to the characters moved by earlier _S_move, compute the source address using expression based on the __p pointer rather than __s pointer. * g++.dg/warn/Wstringop-overread-1.C: New test.
2021-01-04Update copyright years.Jakub Jelinek
2020-10-14libstdc++: Define some std::string constructors inlineJonathan Wakely
There are a lot of very simple constructors for the old string which are not defined inline. I don't see any reason for this and it probably makes them less likely to be optimized away. Move the definitions into the class body. libstdc++-v3/ChangeLog: * include/bits/basic_string.h (basic_string(const Alloc&)) (basic_string(const basic_string&) (basic_string(const CharT*, size_type, const Alloc&)) (basic_string(const CharT*, const Alloc&)) (basic_string(size_type, CharT, const Alloc&)) (basic_string(initializer_list<CharT>, const Alloc&)) (basic_string(InputIterator, InputIterator, const Alloc&)): Define inline in class body. * include/bits/basic_string.tcc (basic_string(const Alloc&)) (basic_string(const basic_string&) (basic_string(const CharT*, size_type, const Alloc&)) (basic_string(const CharT*, const Alloc&)) (basic_string(size_type, CharT, const Alloc&)) (basic_string(initializer_list<CharT>, const Alloc&)) (basic_string(InputIterator, InputIterator, const Alloc&)): Move definitions into class body.
2020-08-10libstdc++: Check __cpp_exceptions in basic_string::reserve()Jonathan Wakely
If exceptions are disabled then reallocating could abort, so ignore shrink-to-fit requests. libstdc++-v3/ChangeLog: * include/bits/basic_string.tcc [_GLIBCXX_USE_CXX11_ABI=0] (basic_string::reserve()): Do nothing if exceptions are not enabled.
2020-08-06libstdc++: Implement P0966 std::string::reserve should not shrinkAndrew Luo
Remove ability for reserve(n) to reduce a string's capacity. Add a new reserve() overload that makes a shrink-to-fit request, and make shrink_to_fit() use that. libstdc++-v3/ChangeLog: 2020-07-30 Andrew Luo <andrewluotechnologies@outlook.com> Jonathan Wakely <jwakely@redhat.com> * config/abi/pre/gnu.ver (GLIBCXX_3.4): Use less greedy patterns for basic_string members. (GLIBCXX_3.4.29): Export new basic_string::reserve symbols. * doc/xml/manual/status_cxx2020.xml: Update P0966 status. * include/bits/basic_string.h (shrink_to_fit()): Call reserve(). (reserve(size_type)): Remove default argument. (reserve()): Declare new overload. [!_GLIBCXX_USE_CXX11_ABI] (shrink_to_fit, reserve): Likewise. * include/bits/basic_string.tcc (reserve(size_type)): Remove support for shrinking capacity. (reserve()): Perform shrink-to-fit operation. [!_GLIBCXX_USE_CXX11_ABI] (reserve): Likewise. * testsuite/21_strings/basic_string/capacity/1.cc: Adjust to reflect new behavior. * testsuite/21_strings/basic_string/capacity/char/1.cc: Likewise. * testsuite/21_strings/basic_string/capacity/char/18654.cc: Likewise. * testsuite/21_strings/basic_string/capacity/char/2.cc: Likewise. * testsuite/21_strings/basic_string/capacity/wchar_t/1.cc: Likewise. * testsuite/21_strings/basic_string/capacity/wchar_t/18654.cc: Likewise. * testsuite/21_strings/basic_string/capacity/wchar_t/2.cc: Likewise.
2020-08-06libstdc++: Do not set eofbit eagerly in operator>>(istream&, char(&)[N])Jonathan Wakely
Similar to the bugs I fixed recently in istream::ignore, we incorrectly set eofbit too often in operator>>(istream&, string&) and operator>>(istream&. char(&)[N]). We should only set eofbit if we reach EOF but would have kept going otherwise. If we've already extracted the maximum number of characters (whether that's because of the buffer size or the istream's width()) then we should not set eofbit. libstdc++-v3/ChangeLog: * include/bits/basic_string.tcc (operator>>(basic_istream&, basic_string&)): Do not set eofbit if extraction stopped after in.width() characters. * src/c++98/istream-string.cc (operator>>(istream&, string&)): Likewise. * include/bits/istream.tcc (__istream_extract): Do not set eofbit if extraction stopped after n-1 characters. * src/c++98/istream.cc (__istream_extract): Likewise. * testsuite/21_strings/basic_string/inserters_extractors/char/13.cc: New test. * testsuite/21_strings/basic_string/inserters_extractors/wchar_t/13.cc: New test. * testsuite/27_io/basic_istream/extractors_character/char/5.cc: New test. * testsuite/27_io/basic_istream/extractors_character/wchar_t/5.cc: New test.
2020-04-29libstdc++: Fix outdated comment about std::string instantiations (PR 94854)Jonathan Wakely
PR libstdc++/94854 * include/bits/basic_string.tcc: Update comment about explicit instantiations.
2020-01-01Update copyright years.Jakub Jelinek
From-SVN: r279813
2019-05-30LWG2788 basic_string spurious use of a default constructible allocatorNina Dinka Ranns
This only change the cxx11 basic_string, because COW strings don't correctly propagate allocators anyway. 2019-05-30 Nina Dinka Ranns <dinka.ranns@gmail.com> LWG2788 basic_string spurious use of a default constructible allocator * include/bits/basic_string.tcc [_GLIBCXX_USE_CXX11_ABI] (basic_string::_M_replace_dispatch): Construct temporary string with the current allocator. * testsuite/21_strings/basic_string/allocator/char/lwg2788.cc: New. * testsuite/21_strings/basic_string/allocator/wchar_t/lwg2788.cc: New. From-SVN: r271789
2019-05-07Make allocator propagation more consistent for operator+(basic_string) (P1165R1)Nina Dinka Ranns
2019-05-01 Nina Dinka Ranns <dinka.ranns@gmail.com> Make allocator propagation more consistent for operator+(basic_string) (P1165R1) * include/bits/basic_string.h (operator+(basic_string&&, basic_string&&): Changed resulting allocator to always be the one from the first parameter. * include/bits/basic_string.tcc (operator+(const _CharT*, const basic_string&)): Changed resulting allocator to be SOCCC on the second parameter's allocator. (operator+(_CharT, const basic_string&)): Likewise. * testsuite/21_strings/basic_string/allocator/char/operator_plus.cc: New. * testsuite/21_strings/basic_string/allocator/wchar_t/operator_plus.cc: New. From-SVN: r270953
2019-01-04Export explicit instantiations for C++17 members of std::stringJonathan Wakely
The C++17 standard added some new members to std::basic_string, which were not previously instantiated in the library. This meant that the extern template declarations had to be disabled for C++17 mode. With this patch the new members are instantiated in the library and so the explicit instantiation declarations can be used for C++17. The new members added by C++2a are still not exported, and so the explicit instantiation declarations are still disabled for C++2a. * config/abi/pre/gnu.ver (GLIBCXX_3.4.21): Make patterns less greedy for const member functions of std::basic_string. (GLIBCXX_3.4.26): Export member functions of std::basic_string added in C++17. * include/bits/basic_string.h (basic_string(__sv_wrapper, const A&)): Make non-standard constructor private. [!_GLIBCXX_USE_CXX11_ABI] (basic_string(__sv_wrapper, const A&)): Likewise. * include/bits/basic_string.tcc (std::string, std::wstring): Declare explicit instantiations for C++17 as well as earlier dialects. * src/c++17/Makefile.am: Add new source files. * src/c++17/Makefile.in: Regenerate. * src/c++17/cow-string-inst.cc: New file defining explicit instantiations for basic_string member functions added in C++17. * src/c++17/string-inst.cc: Likewise. From-SVN: r267585
2019-01-01Update copyright years.Jakub Jelinek
From-SVN: r267494
2018-07-05PR libstdc++/58265 implement LWG 2063 for COW stringsJonathan Wakely
For COW strings the default constructor does not allocate when _GLIBCXX_FULLY_DYNAMIC_STRING == 0, so can be noexcept. The move constructor and swap do not allocate when the allocators are equal, so add conditional noexcept using allocator_traits::is_always_equal. PR libstdc++/58265 * include/bits/basic_string.h [!_GLIBCXX_USE_CXX11_ABI] [_GLIBCXX_FULLY_DYNAMIC_STRING==0] (basic_string::basic_string()): Add GLIBCXX_NOEXCEPT. (basic_string::operator=(basic_string&&)): Add _GLIBCXX_NOEXCEPT_IF to depend on the allocator's is_always_equal property (LWG 2063). (basic_string::swap(basic_string&)): Likewise. * include/bits/basic_string.tcc [!_GLIBCXX_USE_CXX11_ABI] (basic_string::swap(basic_string&)): Likewise. * testsuite/21_strings/basic_string/allocator/char/move_assign.cc: Check is_nothrow_move_assignable. * testsuite/21_strings/basic_string/allocator/wchar_t/move_assign.cc: Check is_nothrow_move_assignable. * testsuite/21_strings/basic_string/cons/char/ noexcept_move_construct.cc: Likewise. * testsuite/21_strings/basic_string/cons/wchar_t/ noexcept_move_construct.cc: Likewise. From-SVN: r262443
2018-06-27Declare some explicit instantiations for strings in Debug ModeJonathan Wakely
The empty reps and the I/O functions do not need to be implicitly instantiated to enable assertions, so declare the explicit instantiations when _GLIBCXX_EXTERN_TEMPLATE == -1 (i.e. when _GLIBCXX_ASSERTIONS is defined). PR libstdc++/86138 * include/bits/basic_string.tcc: [_GLIBCXX_EXTERN_TEMPLATE < 0] Declare explicit instantiations of COW empty reps and I/O functions. From-SVN: r262167
2018-06-22PR libstdc++/86138 prevent implicit instantiation of COW empty repJonathan Wakely
The explicit instantiation declarations for std::basic_string are disabled for C++17 (and later) so that basic_string symbols get implicitly instantiated in every translation unit that needs them. On targets that don't support STB_GNU_UNIQUE this leads to multiple copies of the empty rep symbol for COW strings. In order to detect whether a COW string needs to deallocate its storage it compares the address with the empty rep. When there are multiple copies of the empty rep object the address is not unique, and so string destructors try to delete the empty rep, which crashes. In order to guarantee uniqueness of the _S_empty_rep_storage symbol this patch adds an explicit instantiation declaration for just that symbol. This means the other symbols are still implicitly instantiated in C++17 code, but for the empty rep the definition in the library gets used. Separately, there is no need for C++17 code to implicitly instantiate the I/O functions for strings, so this also restores the explicit instantiation declarations for those functions. PR libstdc++/86138 * include/bits/basic_string.tcc: [__cplusplus > 201402 && !_GLIBCXX_USE_CXX11_ABI] (basic_string<char>::_Rep::_S_empty_rep_storage) (basic_string<wchar_t>::_Rep::_S_empty_rep_storage): Add explicit instantiation declarations. [__cplusplus > 201402] (operator>>, operator<<, getline): Re-enable explicit instantiation declarations. * testsuite/21_strings/basic_string/cons/char/86138.cc: New. * testsuite/21_strings/basic_string/cons/wchar_t/86138.cc: New. From-SVN: r261873
2018-01-03Update copyright years.Jakub Jelinek
From-SVN: r256169
2017-02-01PR libstdc++/79254 simplify exception-safety in copy assignmentJonathan Wakely
PR libstdc++/79254 * config/abi/pre/gnu.ver: Remove recently added symbols. * include/bits/basic_string.h [_GLIBCXX_USE_CXX11_ABI] (basic_string::_M_copy_assign): Remove. (basic_string::operator=(const basic_string&)): Don't dispatch to _M_copy_assign. If source object is small just deallocate, otherwise perform new allocation before making any changes. * include/bits/basic_string.tcc [_GLIBCXX_USE_CXX11_ABI] (basic_string::_M_copy_assign(const basic_string&, true_type)): Remove. * testsuite/21_strings/basic_string/allocator/char/copy_assign.cc: Test cases where the allocators are equal or the string is small. * testsuite/21_strings/basic_string/allocator/wchar_t/copy_assign.cc: Likewise. From-SVN: r245085
2017-01-27PR libstdc++/79254 fix exception-safety in std::string::operator=Jonathan Wakely
PR libstdc++/79254 * config/abi/pre/gnu.ver: Add new symbols. * include/bits/basic_string.h [_GLIBCXX_USE_CXX11_ABI] (basic_string::_M_copy_assign): New overloaded functions to perform copy assignment. (basic_string::operator=(const basic_string&)): Dispatch to _M_copy_assign. * include/bits/basic_string.tcc [_GLIBCXX_USE_CXX11_ABI] (basic_string::_M_copy_assign(const basic_string&, true_type)): Define, performing rollback on exception. * testsuite/21_strings/basic_string/allocator/char/copy_assign.cc: Test exception-safety guarantee. * testsuite/21_strings/basic_string/allocator/wchar_t/copy_assign.cc: Likewise. * testsuite/util/testsuite_allocator.h (uneq_allocator::swap): Make std::swap visible. From-SVN: r244986
2017-01-09PR66414 optimize std::string::findJonathan Wakely
2017-01-09 Jonathan Wakely <jwakely@redhat.com> Aditya Kumar <hiraditya@msn.com> PR libstdc++/66414 * include/bits/basic_string.tcc (basic_string::find(const CharT*, size_type, size_type)): Optimize. Co-Authored-By: Aditya Kumar <hiraditya@msn.com> From-SVN: r244225
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